Tuesday, April 30, 2013

Hard Disk Selector

In the last few years, the available range of operating systems for PCs has increased dramatically. Various free (!) operating systems have been added to the list, such as BeOS, OpenBSD and Linux. These systems are also available in different colours and flavours (versions and distributions). Windows is also no longer simply Windows, because there are now several different versions (Windows 95, 98, ME, NT, XP, Vista and 7). Computer users thus have a large variety of options with regard to the operating system to be used. One problem is that not all hardware works equally well under the various operating systems, and with regard to software, compatibility is far from being universal. In other words, it’s difficult to make a good choice.


Switching from one operating system to another - that’s a risky business, isn’t it? Although this may be a bit of an exaggeration, the safest approach is still to install two different operating systems on the same PC, so you can always easily use the ‘old’ operating system if the new one fails to meet your needs (or suit your taste). A software solution is often used for such a ‘dual system’. A program called a ‘boot manager’ can be used to allow the user to choose, during the start-up process, which hard disk will be used for starting up the computer. Unfortunately, this does not always work flawlessly, and in most cases this boot manager is replaced by the standard boot loader of the operating system when a new operating system is installed.

In many cases, the only remedy is to reinstall the software. The solution presented here does not suffer from this problem. It is a hardware solution that causes the primary and secondary hard disk drives to ‘swap places’ when the computer is started up, if so desired. From the perspective of the computer (and the software running on the computer), it appears as though these two hard disks have actually changed places. This trick is made possible by a feature of the IDE specification called ‘CableSelect’. Every IDE hard disk can be configured to use either Master/Slave or CableSelect. In the latter case, a signal on the IDE cable tells the hard disk whether it is to act as the master or slave device. For this reason, in every IDE cable one lead is interrupted between the connectors for the two disk drives, or the relevant pin is omitted from the connector.


This causes a low level to be present on the CS pin of one of the drives and a high level to be present on the CS pin of the other one (at the far end of the cable). The circuit shown here is connected to the IDE bus of the motherboard via connector K1. Most of the signals are fed directly from K1 to the other connectors (K2 and K3). An IDE hard disk is connected to K2, and a second one is connected to K3. When the computer is switched on or reset, a pulse will appear on the RESET line of the IDE interface. This pulse clocks flip-flop IC1a, and depending on the state of switch S1, the Q output will go either high or low. The state on the Q output is naturally always the opposite of that on the Q output. If we assume that the switch is closed during start-up, a low level will be present on D input of IC1a, so the Q output will be low following the reset pulse.


This low level on the Q output will cause transistor T1 to conduct. The current flowing through T1 will cause LED D1 to light up and transistor T2 to conduct. The hard disk attached to connector K2 will thus see a low level on its CS pin, which will cause it to act as the master drive and thus appear to the computer as the C: drive. A high level will appear on the Q output following the reset pulse. This will prevent T3 and T4 from conducting, with the consequence that LED D2 will be extinguished and the hard disk attached to connector K3 will see a high level on its CS pin. For this disk, this indicates that it is to act as a slave drive (D: drive).


If S1 is open when the reset pulse occurs, the above situation is of course reversed, and the hard disk attached to connector K2 will act as the D: drive, while the hard disk attached to connector K3 will act as the C: drive. Flip-flop IC1a is included here to prevent the hard disks from swapping roles during use. This could have disastrous consequences for the data on the hard disks, and it would most likely cause the computer to crash. This means that you do not have to worry about affecting the operation of the computer if you change the switch setting while the computer is running. The state of the flip-flop, and thus the configuration of the hard disks, can only be changed during a reset.

The circuit is powered from a power connector for a 3.5-inch drive. This advantage of using this connector is that it easily fits onto a standard 4-way header. However, you must observe the correct polarity when attaching the connector. The red lead must be connected to pin 1. Constructing the hard disk selector is easy if the illustrated printed circuit board is used. You will need three IDE cables to connect the circuit. The best idea is to use short cables with only two connectors, with all pins connected 1:1 (no interruption in the CS line). The IDE connector on the motherboard is connected to K1 using one cable. A cable then runs from K2 to first hard disk, and another cable runs from K3 to the second hard disk. This means that it is not possible to connect more than two hard disks to this circuit. You must also ensure that the jumpers of both disk drives are configured for CableSelect. To find out how to do this, refer to the user manual(s) for the drives.
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Single Cell LED Flashlight

High efficiency white LEDs have advanced to the point where they can replace glow bulbs and other light sources not only as indicators, but also for illumination. While many of the claims made about the LEDs efficiency, light quality, lifetime and economy are mostly exaggeration, the truth is that for very low light levels they are now competitive. They have equal or slightly higher efficiency than a flashlight bulb, a longer lifetime, and are very much tougher. On the other hand, they are still far more expensive than a bulb, for a given light output.

Circuit Project: Single Cell LED Flashlight

It follows that LEDs are almost ideal for very tiny, low power flashlights, in the less-than-one-watt category. But such a low power flashlight makes sense only if the whole flashlight is small and lightweight, and has a reasonable battery lifetime. But white LEDs require about 3.3 volts each, and typically some extra voltage is needed to provide room for current regulation! Thats why most commercial LED flashlights use at least three alkaline or NiMH cells, or a lithium cell. And often they cant use their batteries all the way down to the true end of their charges!

Using three AA cells isnt really practical for a small flashlight, simply because it will no longer be small! Lithium cells are expensive. So some manufacturers use three button cells, but these last only for minutes and are also expensive compared to their tiny energy contents! So I set out to build a circuit that lights a string of white LEDs, using a single alkaline or NiMH cell. That allows using the widely available and inexpensive AA cell, obtaining a small size, low cost and good runtime.

A typical white LED has its best power-efficiency combination at about 20mA, and needs about 3.3V. This makes for a power of about 66mW per LED. I decided to use seven LEDs, because they can be arranged in a nice and compact way with one in the middle and the other six around, and the whole array runs at close to one half watt, which is a reasonable power for a tiny pocket flashlight. To avoid having to control the current separately for each LED, the LEDs were arranged in series. So, I needed a driver circuit that will provide about 23V at 20mA, when fed from a 1.2V NiMH rechargeable cell  or from a 1.5V alkaline cell. It should be ultra simple, low cost, efficient and reliable. And here it is!

The circuit is a self-oscillating boost converter, and I certainly cannot claim having invented it. It is ages old! I only did the detail design of this one, and optimized it in the course of one afternoon. It runs with a beautifully clean waveform, with all components except the LEDs staying completely cold to the touch. At this low power level, even that doesnt guarantee a good efficiency, but I measured it at about 72%, which is quite good for a circuit operating from such a low voltage!

How it works:

When switching it on, R1 and D1 bias the transistor into the linear range, through the feedback winding on T1. That causes a current through the 18 turn winding, and thanks to the positive feedback the transistor is driven into saturation. At this moment there will be a base current defined like this: The 1.2V of the cell, plus the 0.2V induced in the feedback winding, minus the 0.7V base-emitter drop of the transistor, make a total of 0.7V, which applied to the 22 ohm resistor gives about 32mA base current. D1 is not conducting a significant current at this time, because the transistor clamps the base voltage to 0.7V and the 3 turn winding subtracts 0.2V from this, so that we end up with only 0.5V across the diode.

This base current keeps the transistor in saturation until its collector current reaches approximately 1A, while the transformer loads up. At this point the transistor will start getting out of saturation, which makes the feedback voltage drop. This very quickly puts the transistor into blockage. The collector voltage will soar as T1 forces current to keep flowing, until D2 starts conducting and discharges the transformer into C2, by means of a quite narrow pulse. During operation this pulse is about 24V high, so that the feedback winding develops -4V, which results in applying about -3.3V to Q1s base, enough to switch it off very fast, but not enough to make the base reverse-conduct.

As soon as the transformer has fully discharged into C2, the voltage on it breaks down, and the transistor enters conduction to start a new cycle. The oscillating frequency is 30kHz, and the transformer operates at a peak flux density of 0.1 tesla, far away from saturation, and low enough to have very low loss. C2 has to eat the load pulses that start at about 1A, and has to keep the voltage constant enough to feed the LEDs an almost smooth DC. The value given works well. If anyone wants to build this circuit to run 24 hours a day for 30 years, it would be good to pick a capacitor rated for low ESR and a relatively high ripple current, but for flashlight use a plain standard 47µF, 35V electrolytic capacitor works great.

C1 is not strictly necessary. With a good NiMH cell, the circuit works the same without it, so you can save a few cents here. But with the capacitor in place, the circuit keeps working better when the cell is almost fully discharged and its internal resistance gets higher, so its better to include it.

Components:

Of course, the part over which most builders will stumble is the transformer. I used an Amidon EA-77-188 core, because I had it at hand, and it was the smallest core I had. I should say that this core is still at least five times larger than required! So feel free to use the smallest ferrite double-E core you can find, or any other ferrite core that offers a closed loop and the possibility of assembling it with an air gap. But then you will have to redo the math!

The main winding has 18 turns, and I wound it with 7 strands of #30 enameled wire twisted together, simply because there is room enough to do so. But this thick wire bundle is huge overkill, like the whole transformer is! The feedback winding  was wound with a single strand of that same #30 wire, and it has just three turns. The phasing is like shown in the diagram, of course. If you get the phasing wrong, the circuit wont work and the transistor will get warm.

I used masking tape to hold the windings in place on the bobbin. No special insulation is required, because the voltages are so low that the enamel on the wire is insulation enough.

Now comes a very important step: This transformer is airgapped. The two core halves need to be separated by a distance of 0.1mm. I simply stuck little pieces of masking tape on the three legs of one core half, taking advantage of the fact that my masking tape is just the right thickness! Then I assembled the core, wrapping masking tape around it to hold it together.

If you have to use a different ferrite core, you can use my transformers and coils article to learn how to design your transformer. The turns ratio will of course remain 6:1, but the absolute number of turns will change in inverse proportion  to the cores cross section. You can look up the data of my core on Amidons or Bytemarks websites, compare that to the data for your core, and go from there. After calculating the turns numbers, you have to calculate the required air gap to obtain an inductance of the main winding of about 40µH.

The transistor I used, the 2SC1226A, is a pretty old part and may no longer be available. I have a bunch of them, so I used it. It has a soft, thin copper tab which can easily be cut off, which is an advantage in this circuit, because it allows saving some space! The transistor works cold, so it doesnt really need the tab! If you have to use another transistor instead, feel free, but look for one which has the proper characteristics: It should have a breakdown voltage of about 40V, a maximum continuous current of about 3A, be reasonably fast (mine is very fast, having an Ft of 150MHz!), it should have good saturation characteristics, and it should have a reasonably high hfe (at least 30, ideally about 100) at a current of 1A.

Any different transistor will most likely require a change in the value of R1, to set the proper power level for the LEDs. You can experimentally determine that resistor value, by placing a milliamperemeter in series with the LED string, and selecting the resistor for 20mA in the LEDs. By the way, if you want to build this circuit for an alkaline cell instead of a NiMH cell, the resistor should be a bit higher. D2 is a Schottky rectifier. A non-Schottky ultrafast diode could be used too, but the Schottky is better. D1 instead is any plain simple silicon diode.

If your power switch doesnt have very low resistance, it might cause a significant loss in this low voltage circuit! If that happens, you could instead place the power switch in series with R1, leaving the rest of the circuit permanently energized. That will cost almost no lost battery power, because the only current drain when off will be the leakage through the parts, which should be in the microampere range. But if you place the switch at R1, you should also place a 1 megaohm resistor (or almost any other high value) in parallel with D1, to make sure that the transistor really does stay fully off when it should!
 
 
Source: Humo Ludens
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Sunday, April 21, 2013

Real Time Clock Using the PIC16CXXX

A very simple real time clock electronic project can be designed using the PIC16CXXX microcontroller family , designed by Microchip Technology . This real time clock electronic project uses the Timer1 module, from a mid-range PIC16CXXX microcontroller, to control a low-power real-time clock. Timer1 was chosen because it has its own crystal which allows the module to operate during sleep.

Upon power-up, the device is initialized with the display starting at 12:00 PM, and Timer1 is configured to generate an interrupt (every second). The Timer1 overflow interrupt wakes the device from sleep. This causes the time registers (HRS, MIN, SECS) to be updated. If the SECS register contains an even value (SECS<0> = 0), the colon (":") is not displayed. This gives a visual indication for each second. Then the device returns to sleep.

Real Time Clock Circuit Diagram
For setting the clock are used three keys : SELECT_UNITS Key (S1) selects which units are to be modified (hours, minutes, off), the INC Key (S2) increments the selected units and CLR_MIN Key (S3) clears the minutes and seconds (useful for exactly setting the time ) .

This simplify design use a standard Hitachi LCD display module and some other electronic parts .

The RA2:RA0 pins are the control signals to the LCD display, RB3:RB0 acts as a 4-bit data bus, and RB7:RB5 are the input switches. The OSC1 pin is connected to an RC network, which generates an approximate 4 MHz device frequency. Because Timer1 operates asynchronously to the device, the devices oscillator can be configured for RC mode.

Timer1’s crystal is connected to the T1OSI and T1OSO pins. A good choice for a crystal is a 32.786 kHz (watch) crystal.

This electronic project and source code was designed by Mark Palmer Microchip Technology Inc.
 
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Saturday, April 13, 2013

Simple 500W Audio Power Amplifier Circuit Diagram with Transistor

We take transistor MJL2194 and MJL2193 for pressure output signal.so the amp has a capability for enormous instantaneous current potential.

Simple 500W Audio Power Amplifier Circuit Diagram with Transistor

Circuit Functional
I use the -85 volt when the output current is supplied to the drive 350 to 340 very hot. Increase the output present, but it was once too chilly. The output to warmth up sooner than a regular open it. Sounds evident, but sound high quality is somewhat excellent.

I recomment it by way of turning out for the evening. If the force is installed on the steel part out.

I assume simple. View full above, the statement that R 30 ohm then the voltage throughout the 0.86 V exhibit that the brand new via its 29 mA for those who add a file to / – eighty five V, and think that the voltage throughout the part physique. It was the identical in each the R 30 ohm to get an awfully light 5 zero.86 = 5.86 V and the present I can be 5.86/30 = zero.195 A = 195 mA, and the specification of mje340. mje350 get Ic (max) = 500 mA, so it is pure for it to heat up. Actually, it isn't essential to adhere to sync tr output must be interested in the following two tr power force is healthier. For VR will have to be R300 .


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zBot 10 A Power Stage for DC Motor

If\r\n you take a look at the chassis of the zBot vehicle1, you’ll find two sections \r\nrequiring intelligent keep a watch on: the steerage servo and the DC motor. The \r\nso known as H-bridge is the normal circuit for electronic control of \r\nrevolution pace and route. The DC motor of a Tamiya automobile is powerful\r\n sufficient to propel zBot at as so much as 20 miles per hour.
The\r\n motor then consumes more than 10 A, so we make a selection high-current energy \r\nMOSFETs for the cause force stage. There are numerous totally different softwares to \r\nchoose from. The MOSFET we require has to provide the maximum motor \r\ncurrent and, importantly, it needs to be switched with gate voltages of \r\nabout 5 V. In this case, the microcontroller switches the ability stage \r\n(‘low aspect’) directly. For high aspect riding degree shifters are \r\nnecessary. The schematic of the H-bridge power stage presentations a few \r\ninverters, NAND gates and two tri-stateable drivers. These logic \r\nfunctions are essential as the better approach, i.e.., in an instant \r\ncontrolling all 4 MOSFET has a fatal disadvantage.


In\r\n case of a software crash it may well happen that two ore extra MOSFETs are \r\nswitched on incor-rectly for exam-ple, T4 and T7. In that case, the \r\ncurrent throughout the transistors is proscribed by using the interior resistors of \r\nthe MOSFETs (about 10 mO) simplest. Such a deadly error would destroy the \r\nMOSFETs. The common sense performs configured here successfully avoid illegal \r\nstates.To keep an eye fixed on the DC motor, three signals are needed: DIR, PWM and \r\nSTOP. DIR regulates the path of the motor revolution, PWM the rate,\r\n and STOP brakes the motor.

The\r\n software program module for the DC motor is called dcm.c.(070172-I) The \r\ncomplete document referred to as Zbot  the Robot Experimental Platform is \r\navailable free of charge downloading from the Elektor Electronics site. The\r\n file quantity is 070172-11.zip (July/August 2007).
 
 
http://www.ecircuitslab.com
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Descrete Multistage Light Sequencer

The drawing below illustrates a multistage light sequencer using descrete parts and no integrated circuits. The idea is not new and I hear a similar circuit was developed about 40 years ago using germanium transistors. The idea is to connect the lights so that as one turns off it causes the next to turn on, and so forth. This is accomplished with a large capacitor between each stage that charges when a stage turns off and supplies base current to the next transistor, thus turning it on. Any number of stages can be used and the drawing below illustrates 3 small Christmas lights running at about 5 volts and 200mA. The circuit may need to be manually started when power is applied. To start it, connect a momentary short across any one of the capacitors and then remove the short. You could use a manual push button to do this. 

Detailed operation:
Assume the circuit doesnt start when power is applied amd all lights are off and all three capacitors are charged to about 5 volts. We connect a jumper across the 220uF capacitor on the left which discharges the capacitor and turns on the 2nd stage transistor and corresponding light. When the jumper is removed, the capacitor will start charging through the base of the stage 2 transistor and stage 1 light. 
 
This causes the stage 2 transistor to remain on while the capacitor continues to charge. At the same time, the capacitor connecting stage 2 and 3 will discharge through the 100 ohm resistor and diode and stage 2 transistor. When the capacitor charging current falls below what is needed to keep stage 2 turned on, the transistor and light will turn off causing the voltage at the collector of the stage 2 transistor to rise to 5 volts. 
 
Since the capacitor connecting stage 2 and 3 has discharged and the voltage rises at the collector of stage 2, the capacitor from stage 2 and 3 will charge causing the 3rd stage to turn on and the cycle repeats for sucessive stages 4,5,6,7.... and back to 1. The sequence rate is determined by the capacitor and resistor values (220uF and 100 ohms in this case), load current (200mA in this case), and current gain of the particular transistor used. This arrangement runs at about 120 complete cycles per minute for 3 lights, or about 167mS per light. Faster or slower rates can be obtained with different capacitor values. 
 
 
 
 
Sourced by : bowdenshobbycircuits.info
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Rise Nikon Camera Remote Control

Overview

This is an IR remote control for Nikon cameras. It is compatible with the Nikon ML-L3 remote control. Supported cameras include: D40, D40X, D50, D60, D70, D70s, D80, Coolpix 8400 8800. This design is based on an idea from http://www.bigmike.it/ircontrol/.

Hardware

The circuit is extremely simple: an ATtiny13V, button, transistor, resistor, IR diode and 3V battery. You could even omit the transistor and resistor, and connect the IR diode directly to the ATtiny13V, but that will limit the LED current and therefor the range.

schematic

I chose to power the circuit permanently, and connect the button to an input, instead of controlling the power with the button. This ensures that the IR sequence is always completely sent, even when you release the button too early, and that contact bounce may be filtered. The standby power consumption is so low, about the same as the self-discharge rate of the lithium battery, that this does not really affect the battery life.
The internal oscillator of the ATtiny13V is used as a clock source, which seems to be sufficiently accurate. To get optimal results, you may want to calibrate the internal oscillator. See main.c for details.
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1963 Dodge Dart Electrical Wiring Diagram

1963 Dodge Dart Electrical Wiring Diagram
The Part of 1963 Dodge Dart Electrical Wiring Diagram: direction signal switch connector, cigar lighter, ammeter, heater blower switch, the stop light and direction signal, tail light, beam selector switch, light switch, luggage compartment, circuit breaker, gas gauge, backup light, printed circuit connector, parking brake warning light and switch, etc. Features: lower-priced, shorter wheelbase, full-size Dodge.
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Friday, April 12, 2013

1998 Isuzu Rodeo 3 2 6 cyl Wiring Diagram

1998 Isuzu Rodeo 3.2 6 cyl Wiring Diagram


The Part of 1998 Isuzu Rodeo 3.2 6 cyl Wiring Diagram: red wire, coil contact, headlight relay,
connector, relay ctrl, fuse box, rear wipper, starter, theft horn, black wire, horn, hazard
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High Performance Interruption Detector

The circuit presented here detects interruption in security systems. Its features include no false triggering by external factors (such as sun-light and rain), easy relative positioning of the sensors and alignment of the circuit, high sensitivity, and reliability. The circuit comprises three sections, namely, transmitter, receiver, and power supply. The transmitter generates modulated IR signals and the receiver detects the change in IR intensity. Power supply provides regulated +5V to the transmitter and the receiver. 

The power supply and the speaker are kept inside the premises while the transmitter and the receiver are placed oppo site to each other at the entrance where the detection is needed. Three connections (Vcc, GND, and SPKR) are needed from the power supply/speaker to the receiver section, while only two connections (Vcc and GND) are required to the transmitter. The transmitter is basically an astable multivibrator configured around NE555 (IC3). Its frequency should match the frequency of the detector/sensor module (36 kHz for the module shown in figure) in the receiver. The transmitter frequency is adjusted by preset VR2. For making the duty cycle less than 50 per cent, di-ode 1N4148 is connected in the charging path of capacitor C7. 

The output of astable multivibrator modulates the IR signal emitted from IR LEDs that are used in series to obtain a range of 7 metres (maximum). To increase the range any further, the transmitted power has to be raised by using more number of IR LEDs. In such a case, it is advisable to use another pair of IR LEDs and 33-ohm series resistor in parallel with the existing IR LEDs and resistor R5 across points X and Y. The receiver unit consists of a monostable multivibrator built around NE555 (IC2), a melody generator, and an IR sensor module. The output of the IR sensor module goes high in the standby mode or when there is continuous presence of modulated IR signal.
Circuit diagram :
High-Performance-Interruption-Detector-Circuit-Diagram
High-Performance Interruption Detector Circuit Diagram
 
When the IR signal path is blocked, the output of the sensor module still re-mains high. However, when the block is removed, the output of the sensor module briefly goes low to trigger monostable IC3. This is due to the fact that the sensor module is meant for pulsed operation. Thus interruption of the IR path for a brief period gives rise to pulsed operation of the sensor module. Once monostable IC2 gets triggered, its output goes high and stays in that state for the duration of its pulse width that can be controlled by preset VR1. The high output at pin 3 of the monostable makes the musical IC to function. Voltage divider comprising R2 and R3 reduces the 555 output voltage to a safer value (around 3V) for UM66 operation. The du-ration of the musical notes is set by pre-set VR1 as stated earlier. 

For proper operation of the circuit, use 7.5V to 12V power supply. A battery backup can be provided so that the circuit works in the case of power failure also. Potmeter VR3 serves as a volume control. The transmitter, receiver, and power supply units should be assembled separately. The transmitter and the receiver should have proper coverings (booster) for protection against rain. The length of the wire used for connecting the IR sensor module and IR LEDs should be minimum. 


Streampowers
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SP Semi Automatic Paintbrush

Got a replacement InkShield and progressing to build an Open hardware project? Then why not strive creating the Semi-Automatic Paintbrush. browse on to grasp a lot of concerning this.



Any work of art are often copied using this and therefore the elements that are needed to form this is often listed below:
IR camera
InkShield
Ink cartridge
IR LED.

The software thats run on a desktop for this purpose is understood as paintbrush.py. The software plays the role of mapping the camera focus with the co-ordinate system of the canvas. Four LEDs are placed at every corner of the canvas and therefore the mapping is calibrated by hitting a key when needed.

The region of the image is captured by tracking the motion of the LEDs. the mandatory commands are send to an Arduino with the InkShield by means that of a script written for this purpose. The script tells the arduino that nozzle to fireplace and additionally the grey level that must be achieved by the firing nozzle. so as to avoid flooding, the painted areas are tracked.

Thats all its. The paintbrush is complete. this is often a lot of of a fun-based project and may be tired some spare time using the elements mentioned earlier. the desired script is out there on github. The InkShield library employed by the 
 
 
 
http://streampowers.blogspot.com/2012/07/sp-semi-automatic-paintbrush.html 
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100W Guitar Pre Amplifier Rise

Introduction
Guitar amplifiers are always an fascinating challenge. The tone controls, gain & overload characteristics are individual, & the ideal combination varies from guitarist to the next, & from guitar to the next. There is no amp that satisfies everyones requirements, & this offering is not expected to be an exception. The preamp is now at Revision-A, & although the whole schematic of the new version is not shown below, the essential characteristics are not changed - it still has the same tone control "stack" & other controls, but now has a second op amp to reduce output impedance & improve gain characteristics.

One major difference from any "store bought" amplifier is that in case you build it yourself, you can alter things to fit your own needs. The ability to experiment is the key to this circuit, which is although introduced in complete form, there is every expectation that builders will make modifications to suit themselves.

The amp is rated at 100W in to a four Ohms load, as this is typical of a "combo" type amp with 8 Ohm speakers in parallel. Alternatively, you can run the amp in to a "quad" box (four x 8 Ohm speakers in series parallel - see Figure five in Project 27b, the original editorial) and will get about 60 Watts. For the adventurous, two quad boxes and the amp head will provide 100W, but will be much louder than the twin. This is a common combination for guitarists, but it does make it hard for the sound man to bring everything else up to the same level.

The Pre-Amplifier
A picture of the Revision-A preamp is shown below. Youll see that theres dual op amps, but the schematic only shows. This is the main part of the Rev-A update - the output section now has gain (which is basically selected), and a better buffered low output impedance. The remainder of the circuit is unchanged.

Guitar Pre-Amplifier Board

The preamp circuit is shown in Figure one, and has a few fascinating characteristics that separate it from the "normal" - assuming that there is such a thing. This is simple but elegant design, that provides excellent tonal range. The gain structure is designed to provide a immense amount of gain, which is ideal for those guitarists who like to get that fully distorted "fat" sound.

However, with a couple of simple changes, the preamp can be tamed to suit any style of playing. Likewise, the tone controls as shown have sufficient range to cover very anything from an electrified violin to a bass guitar - The response can be limited in the event you wish (by experimenting with the tone control capacitor values), but I recommend that you try it "as is" before making any changes.

Figure 1 - Guitar Pre-Amplifier

From Figure one, you can see that the preamp makes use of a dual op amp as its only amplification. The lone transistor is an emitter follower, & maintains a low output impedance after the master volume control. As shown, with a typical guitar input, it is feasible to receive a fat overdrive sound by winding up the volume, & then setting the master for an appropriate level. The general frequency response is deliberately limited to prevent extreme low-end waffle, & to cut the extreme highs to help reduce noise & to limit the response to the normal requirements for guitar. In case you use the TL072 op amp as shown, you may find that noise is an issue - at high gain with lots of treble boost. I strongly recommend that you use an OPA2134 - a premium audio op amp from Los angels Instruments (Burr-Brown division), you will then find this possibly the quietest guitar amp you have ever heard (or not heard :-). At any gain setting, there is more pickup noise from my guitar than circuit noise - & for the prototype one used carbon resistors!

Notes:
one - IC pin outs are industry standard for dual op amps - pin four is -ve supply, and pin 8 is +ve supply.
two - Op amp supply pins must be bypassed to earth with 100nF caps (preferably ceramic) as close as feasible to the op amp itself.
three - Diodes are 1N4148, 1N914 or similar.
four - Pots ought to be linear for tone controls, & log for volume and master.

The power supply section (bottom left corner) connects directly to the main +/-35V power amp supply. Use one Watt zen-er diodes (D5 and D6), and make positive that the zen-er supply resistors (R18 and R19, 680 ohm one Watt) are kept away from other parts, as they will get warm in operation. Again, the preamp PCB accommodates the supply on the board.

The pin connections shown (either huge dots or "port" symbols) are the pins from the PCB. Normally, all pots would be PCB types, and mounted directly to the board. For a do-it-yourself project, that would limit the layout to that imposed by the board, so all connections use wiring. It may look a bit hard, but is simple and looks fine when the unit is done. Cable ties keep the wiring tidy, and only a single connection to the GND point ought to be used(several are provided, so select that suits your layout. VCC is +35V from the main supply, and VEE is the -35V supply.

In the event you dont require all the gain that is available, basically increase the worth of R6 (the first 4k7 resistor) - for even less noise and gain, increase R11 (the second 4k7) as well. For more gain, decrease R11 - I recommend a maximum of 2k2 here.


If the bright switch is bright ( much treble), increase the 1k resistor (R5) to tame it down again. Reduce the worth to get more bite. The tone control arrangement shown will give zero output if all controls are set to maximum - this is unlikely to be a common requirement in use, but be aware of it when testing.

The diode network at the output is designed to permit the preamp to generate a "soft" clipping characteristic when the volume is turned up. Because of the diode clipping, the power amp needs to have an input sensitivity of about 750mV for full output, otherwise it wont be feasible to get full power even with the Master gain control at the maximum setting.

Make positive that the input connectors are isolated from the chassis. The earth isolation parts in the power supply help to prevent hum ( when the amp is connected to other mains powered equipment).
If issues are encountered with this circuit, then you have made a wiring mistake .. period. A golden rule here is to check the wiring, then keep on checking it until you find the error, since I can assure you that if it does not work properly there is at least mistake, & probably more.


The input, effects & output connections are shown in Figure 1B.

Figure 1B - Internal Wiring

The connections shown are similar (ok, virtually identical :-) to those used in my prototype. Noise is low, & probably might have been lower if I had made the amp a tiny bigger. All connectors must be fully insulated types, so there is no connection to chassis. This is important !

You will notice from the above diagram that I didnt include the "loop breaker" circuit shown in the power supply diagram. For my needs, it is not necessary, for your needs, I shall let you pick. In case you select to make use of it, then the earth (chassis) connection marked * (next to the input connectors) must be left off.

A few important points
The main 0 volt point is the connection between the filter caps. This is the reference for all zero volt returns, including the 0.1 ohm speaker feedback resistor. Dont connect the feedback resistor directly to the amps GND point, or you will generate distortion & feasible instability.
 The supply for the amp & preamp must be taken directly from the filter caps - the diagram above is literal - that means that you follow the path of the wiring as shown.
 Although mentioned above, you might well ask why the pots dont mount directly to the PCB to save wiring. Simple . Had I done it that way, you would require to make use of the same type pots as I designed for, & the panel layout would must be the same , with the exact same spacings. I figured that this would be limiting, so wiring it is. The wiring actually doesnt take long & is simple to do, so is not an issue.
 I didnt include the "Bright" switch in Figure 1B for clarity. I expect that it will cause few issues.


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Sound Shifter Using IC HT8950

This is a design circuit for super sound shifter circuit that can be used to add effects to the input sound signal. The circuit is ideal for incorporating in toys and adds great fun. The circuit can be also used in mixers and recorders. The circuit is based on IC HT 8950 from Holtek. The IC HT8905 is a single chip CMOS sound modulator IC which produces seven steps of shift in the frequency of the given sound. This is the complete figure of the circuit.


This circuit is producing a dramatic change in the output. The IC produces two effects robotic and vibrato. The two effects can be selected using push buttons. An audio amplifier IC HT82V 733 is also included in the circuit to amplify the sound out put of HT 8950 to a reasonable level. The 50 K POT can be used as a volume control. The circuit can be powered from a 4.5 V DC supply. The desired sound effects can be selected from the push buttons. All capacitors must be rated 10V. For speaker is using 8 ohm speaker can be used as the load.

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Fire Alarm Using Thermistor

Small and simple unit, Can be used for Home-Security purpose
In this fire alarm circuit, a Thermistor works as the heat sensor. When temperature increases, its resistance decreases, and vice versa. At normal temperature, the resistance of the Thermistor (TH1) is approximately 10 kilo-ohms, which reduces to a few ohms as the temperature increases beyond 100 C. The circuit uses readily available components and can be easily constructed on any general-purpose PCB.

Fire Alarm Using Thermistor Circuit diagram:

Fire Alarm Using Thermistor

Parts Description
R1 470R
R2 470R
R3 33K
R4 560R
R5 470R
R6 47K
R7 2.2K
R8 470R
C1 10uF-16V
C2 0.04uF-63V
C3 0.01uF-63V
Q1 BC548
Q2 BC558
Q3 SL100B
D1 Red Led
D2 1N4001
IC1 NE555
SPKR 1W-8R
TH1 Thermistor-10K

Circuit Operation:

Timer IC NE555 (IC1) is wired as an astable multivibrator oscillating in audio frequency band. Switching transistors Q1 and Q2 drive multivibrator IC1. The output of IC1 is connected to NPN transistor Q3, which drives the loudspeaker (SPKR) to generate sound. The frequency of IC1 depends on the values of resistors R6, R7 and capacitor C2. When Thermistor TH1 becomes hot, it provides a low-resistance path to extend positive voltage to the base of transistor Q1 via diode D2 and resistor R3. Capacitor C1 charges up to the positive voltage and increases the ‘on’ time of alarm. 

The higher the value of capacitor C1, the higher the forward voltage applied to the base of transistor Q1. Since the collector of transistor Q1 is connected to the base of transistor Q2, transistor Q2 provides positive voltage to reset pin 4 of IC1. R5 is used such that IC1 remains inactive in the absence of positive voltage. D2 stops discharging of capacitor C1 when the Thermistor connected to the positive supply cools down and provides a high-resistance (10k) path. It also stops the conduction of Q1. To prevent the Thermistor from melting, wrap it up in mica tape. The circuit works off a 6V-12V regulated power supply. D1 is used to indicate that power to the circuit is switched on.

Source: http://www.ecircuitslab.com/2011/06/fire-alarm-using-thermistor.html

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2009 BMW Z4 Wiring Diagram

2009 BMW Z4 Wiring Diagram



The Part of 2009 BMW Z4 Wiring Diagram: ignition start switch, starter relay, clutch engine switch,
neutral gear switch, hego ground, power ground, exhaust gas oxygen sensor, engine coolant temperature sensor, throttle position, air charger temperature, barometric pressure sensor, EGR valve position sensor, mass air flow sensor, power relay, battery, WAC relay, A/C clutch, pressure switch.
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1998 Chevrolet Suburban 1500 Wirng Diagram

1998 Chevrolet Suburban 1500 Wirng Diagram
(click for full size image)

The Part of 1998 Chevrolet Suburban 1500 Wirng Diagram: headlight, beam, derect, horn, conv centr, switch, marker, battery, blu fuse, neutral switch, dimmer, ignition coil, module, air actuator, coolant sensor, pump connector, thotile, oxigen, map, windshield, alternator.
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Thursday, April 11, 2013

MINIATURE FM TRANSMITTER

DIY Kit 51. MINIATURE FM TRANSMITTER
This FM transmitter is a minuature version of Kit 18 using
normal passive components. Components have been
squashed together as much as possible while still allowing
good access to the tuning capacitor. The PCB-etched
inductor of Kit 18 has been replaced by a small inductor.
To reduce the size any more you would have to use surface
mount components and a double sided PCB.
ASSEMBLY INSTRUCTIONS
Components may be added to the PCB in any order. First
identify the single EC24 inductor. It looks like a 1/2W
resistor. It goes in the location marked L. The electret
microphone should be inserted with the pin connected to
the metal case connected to the negative rail (that is, to the
ground or zero voltage side of the circuit.) This is marked
with a - sign at the MIC on the circuit board. Follow the
overlay to add the other components.
The battery snap must be connected with the Red lead
going to the 9V+ pad and the Black lead going to the - or
ground rail. Adding and removing the batteries acts as a
switch for the kit. Or you may add your own switch.


Connect a half or quarter wavelength length of hookup
wire (supplied by you) to the aerial point. At an FM
frequency of 100 MHz these lengths are 150 cm and 75 cm
respectively.
CIRCUIT DESCRIPTION
The circuit is basically a radio frequency (RF) oscillator
that operates around 100 MHz (100 million cycles per
second). Audio picked up and amplified by the electret
microphone is fed into the audio amplifier stage built
around the first transistor. Output from the collector is fed
into the base of the second transistor where it modulates
the resonant frequency of the tank circuit (the inductor &
the tuning capacitor) by varying the junction capacitance of
the transistor. Junction capacitance is a function of the
potential difference applied to the base of the transistor.
The tank circuit is connected in a Hartley oscillator circuit.
The electret microphone: an electret is a permanently
charged dielectric. It is made by heating a ceramic
material, placing it in a magnetic field then allowing it to
cool while still in the magnetic field. It is the electrostatic
equivalent of a permanent magnet. In the electret
microphone a slice of this material is used as part of the
dielectric of a capacitor in which the diaphram of the
microphone forms one plate. Sound pressure moves one of
its plates. The movement of the plate changes the
capacitance. The electret capacitor is connected to an FET
amplifier. These microphones are small, have excellent
sensitivity, a wide frequency response and a very low cost.


First amplification stage: this is a standard self-biasing
common emitter amplifier. The 4n7 capacitor isolates the
microphone from the base voltage of the transistor and
only allows alternating current (AC) signals to pass.
The tank (LC) circuit: every transmitter needs an
oscillator to generate the radio frequency carrier waves.
The tank (LC) circuit, the BC338 and the feedback 10pF
capacitor are the oscillator in this kit An input signal is not
needed to sustain the oscillation. The feedback signal
makes the base-emitter current of the transistor vary at the
resonant frequency. This causes the emitter-collector
current to vary at the same frequency. This signal fed to
the aerial and radiated as radio waves. The 10pF coupling
capacitor on the aerial is to minimise the effect of the aerial
capacitance on the LC circuit.
The name tank circuit comes from the ability of the LC
circuit to store energy for oscillations. In a pure LC circuit
(one with no resistance) energy cannot be lost. (In an AC
network only the resistive elements will dissipate electrical
energy. The purely reactive elements, the C and the L
simply store energy to be returned to the system later.)
Note that the tank circuit does not oscillate just by having a
DC potential put across it. Positive feedback must be
provided. (Look up Hartley and Colpitts oscillators in a
reference book for more details.)
CALIBRATION
This should be done with the kit at least 10 feet from an
FM radio, preferably in another room. The kit should be
near (note ‘near’, not right next to) some source of sound,
like a TV, ticking clock or just people talking.

Plug in the
battery. Use a small screw driver or your fingernail to
move the movable plates so they are about half
overlapping. Go back to the FM radio and move the tuning
dial at around 90 - 94 MHz. Somewhere there the
transmission should be picked up.
Note that you must not hold the kit when doing this
calibration. Your own body capicitance is more than
enough to change the tank frequency of oscillation.
WHAT TO DO IF IT DOES NOT WORK
Poor soldering is the most likely reason that the circuit
does not work. Check all solder joints carefully under a
good light. Next check that all components are in their
correct position on the PCB. Thirdly, follow the track with
a voltmeter to check the potential differences at various
parts of the circuit particularly across the base, collector
and emitter of the two transistors.
Check that the following collector-emitter voltages are
present; about 2V across the 548, 5V across the 338.
If you hear an oscillation or putt-putt at all frequencies
then it is possible the unit is in oscillation due to the load
resistor on the microphone being too low. Increase it to say
22K or 47K. This should overcome the problem.
See our website for other kits
http://kitsrus.com
DIY Kit 51. MINIATURE FM TRANSMITTER
COMPONENTS
Resistors 5%, 1/4W:
100R brown black brown R1 1
1K brown black red R4 1
12K brown red orange R2 R3 2
2M2 red red green R5 1
Tuning capacitor 2-20pF 1
ceramic capacitor, 4n7 2
ceramic capacitor, 10pF 2
ceramic capacitor, 47pF C 1
Inductor 39nH L 1
BC548 Q1 1
BC338 Q2 1
Electret microphone 1
9V battery snap 1
Kit 51 pcb 1

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Class A power amplifier

Class A power amplifierClass A Power Amplifier
Examples of class A amplifier is the basic transistor circuit common emitter (CE). Amplifier type class A is made by setting dititik bias current (usually Q) on the load line. The position of point Q such a way that is right in the middle line of the load curve VCEIC from the amplifier circuit.



The is an example circuit with common emitter NPN transistor Q1.

Class A schematics power amplifier

Line load on this amplifier determined by the resistor Rc and Re from the formula VCC = VCE + ICRC + IeRe. If Ie = Ic, it can be simplified into VCC = VCE + Ic (Rc + Re). Next line load circuit can be described by a formula them. While resistors Ra and Rb were installed to determine the bias currents. Magnitude resistors Ra and Rb in related series determining how much current Ib the cut point Q. Large Ib flows usually listed on the data sheet used transistors.

Great strengthening AC signals can be calculated with an AC signal circuit analysis theory. In an AC circuit analysis of all components of the capacitor C connected brief and the imaginary connecting the VCC to ground. With In this way a series of images 1-18 can be assembled into such picture 1-20. Resistors Ra and Rc is connected to GND and all short-circuited capacitor.

Typical class A amplifier, all output signals to work on active region. Amplifier type class A is called as a reinforcement that has fidelitas a high level. Provided the signal is still working in the active region, form the output signal will exactly match the input signal. But class A amplifier has low efficiency of approximately only 25% - 50%. Its none other since the point Q is at point A, so that although there is no input signal (or when the input signal = 0 Vac) transistors to keep working in the active region with a constant bias current. Transistor is always active (ON) so that most of the sources of supply wasted power into heat. Since this is class A transistor amplifier should be augmented with extra cooling like heatsinks are more large.
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High Power Car Battary Eliminator

To operate car audio (or video) system from household 230V AC mains supply, you need a DC adaptor. DC adaptors available in the market are generally costly and supply an unregulated DC. To overcome these problems, an economical and reliable circuit of a high-power, regulated DC adaptor using reasonably low number of components is presented here.  Transformer X1 steps down 230V AC mains supply to around 30V AC, which is then rectified by a bridge rectifier comprising 5406 rectifier diodes D1 through D4. The rectified pulsating DC is smoothed by two 4700μF filter capacitors C1 and C2. The next part of the circuit is a seriestransistor regulator circuit realised using high-power transistor 2N3773 (T1). 

High Power Car Battary Eliminator Circuit Daigram 
Fixed-base reference for the transistor is taken from the output pin of 3-pin regulator IC1 (LM 7806). The normal output of IC1 is raised to about 13.8 volts by suitably biasing its common terminal by components ZD1 and LED1. This simple arrangement provides good, stable voltcuit age reference at a low cost. LED1 also works as an output indicator.Finally, a crowbar-type protection circuit is added. If the output voltage exceeds 15V due to some reason such as component failure, the SCR fires because of the breakdown of zener ZD2. Once SCR fires, it presents a short-circuit across the unregulated DC supply, resulting in the blowing of fuse F1 instantly. This offers guaranteed protection to the equipment connected and to the circuit itself.
 High Power Car Battary Eliminator

This circuit can be assembled using a small general-purpose PCB. A goodquality heat-sink is required for transistor T1. Enclose the complete circuit in a readymade big adaptor cabinet as shown in the figure.


Streampowers
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Simple Electronic Lock

There are six (or more) push switches. To unlock you must press all the correct ones at the same time, but not press any of the cancel switches. Pressing just one cancel switch will prevent the circuit unlocking. When the circuit unlocks it actually just turns on an LED for about one second, but it is intended to be adapted to turn on a relay which could be used to switch on another circuit. Please Note: This circuit just turns on an LED for about one second when the correct switches are pressed. It does not actually lock or unlock anything!

Circuit diagram :
 Simple Electronic Lock Circuit Diagram
Simple Electronic Lock Circuit Diagram

Stripboard Layout :

Stripboard Layout
Parts :
  • resistors: 470, 100k ×2, 1M
  • capacitors: 0.1μF, 1μF 16V radial
  • on/off switch
  • push-switch ×6 (or more)
  • stripboard 12 rows × 25 holes
  • red LED
  • 555 timer IC
  • 8-pin DIL socket for IC
  • battery clip for 9V PP3
  •  
A kit for this project is available from RSH Electronics: www.kpsec.freeuk.com



http://streampowers.blogspot.com/2012/06/simple-electronic-lock.html
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Two button Digital Lock

Now here’s a digital lock unlike any other, as  it has only two buttons instead of the usual  numeric keypad. The way it works is as simple  as its keypad. Button S1 is used to enter the  digits of the secret code in a pulsed fashion-i.e. the number of times you press the but-ton is determined by the digit to be entered.  A dial telephone uses the same type of coding (now maybe there’s an idea?). Press four  times for a 4, nine times for a 9, etc. Pressing button S2 indicates the end of a digit. 

 Two-button Digital Lock Project Image:

Two-button Digital Lock Project-Image 

For example, to enter the code 4105, press  S1 four times, then press S2, then S1 once, S2  once, then without pressing S1 at all, press S2  again, then finally S1 five times and S2 once  to finish. If the code is correct, the green LED D1 lights for 2 seconds and the relay is energised for 2 seconds. If the code is wrong, the  red LED D2 lights for 2 seconds, and the relay  is not energised. To change the code, fit a jumper to J1 and  enter the current code. When the green LED  D1 has flashed twice, enter the new 4-digit  code. D1 will flash three times and you will  need to confirm the new code. If this confirmation is correct, D1 will flash four times.  If the red LED D2 flashes four times, some-thing’s wrong and you’ll need to start all over  again. To finish the operation, remove the  jumper and turn the power off and on again the digital lock is now ready for use with  the new code.

Two-button Digital Lock Circuit diagram :
Two-button Digital Lock Circuit-diagram


The software can be found on the webpage for the project [1]. Don’t forget to erase the microcontroller’s EEPROM memory before  programming  it,  so  you  can  be  sure  that  the  default  code  is  1234  and  not  some -thing unknown that was left behind in the  EEPROM. A little exercise for our readers: convert this  project into a single-button digital lock for  example, by using a long press on S1 instead  of pressing S2 to detect the end of a digit.
 
Author : Francis Perrenoud  - Copyright : Elektor

Source : http://www.ecircuitslab.com/2012/02/two-button-digital-lock.html 

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100W Guitar Power Amplifier Rise

The power amp board has remained unchanged since it was first published in 2002. It definitely is not broken, so there is no reason to fix it. The picture below shows a fully assembled board (obtainable as shown as M27). Using TIP35/36C transistors, the output stage is deliberately huge overkill. This ensures reliability under the most arduous stage conditions. No amplifier can be made immune from everything, but this does come close.

Guitar Power Amplifier Board

The power amp (like the earlier version) is loosely based on the 60 Watt amp historically in the past published (Project 03), but its increased gain to match the preamp. Other modifications include the short circuit protection - the tiny groups of parts next to the bias diodes (D2 and D3). This new version is not massively different from the original, but has adjustable bias, and is designed to provide a "constant current" (i.e. high impedance) output to the speakers - this is achieved using R23 and R26. Note that with this arrangement, the gain will change depending on the load impedance, with lower impedance giving lower power amp gain. This is not a controversy, so may safely be ignored.

Ought to the output be shorted, the constant current output characteristic will provide an preliminary level of protection, but is not foolproof. The short circuit protection will limit the output current to a comparatively safe level, but a sustained short will cause the output transistors to fail if the amp is driven hard. The protection is designed not to operate under normal conditions, but will limit the peak output current to about 8.5 Amps. Under these conditions, the internal fuses (or the output transistors) will probably blow if the short is not detected in time.

Figure 2 - Power Amplifier

Figure two shows the power amp PCB parts - except for R26 which doesnt mount on the board. See Figure 1B to see where this ought to be physically mounted. The bias current is adjustable, & ought to be set for about 25mA dormant current (more on this later). The recommendation for power transistors has been changed to higher power devices. This will give improved reliability under sustained heavy usage.

As shown, the power transistors will have an simple time driving any load down to four ohms. In case you dont use the PCB (or are happy to mount power transistors off the board), you can use TO3 transistors for the output stage. MJ15003/4 transistors are high power, & will run cooler because of the TO-3 casing (lower thermal resistance). Watch out for counterfeits though! Theres plenty of other high power transistors that can be used, & the amp is tolerant of substitutes (as long as their ratings are at least equal to the devices shown). The PCB can accommodate Toshiba or Motorola 150W flat-pack power transistors with relative ease - in case you desired to go that way. TIP3055/2966 or MJE3055/2955 may even be used for light or ordinary duty.

At the input finish (as shown in Figure 1B), there is provision for an auxiliary output, & an input. The latter is switched by the jack, so you can use the "Out" & "In" connections for an outside effects unit. Alternatively, the input jack can be used to connect an outside preamp to the power amp, disconnecting the preamp.

The speaker connections permit up to 8 Ohm speaker cabinets (giving four Ohms). Do not use less than four ohm lots on this amplifier - it is not designed for it, & wont give reliable service!

All the low value (i.e. 0.1 & 0.22 ohm) resistors must be rated at 5W. The 0.22 ohm resistors will get warm, so mount them away from other parts. Needless to say, I recommend using the PCB, as this has been designed for optimum performance, and the amp gives an excellent account of itself. So nice in fact, that it may even be used as a hi-fi amp, and it sounds excellent. In case you were to make use of the amp for hi-fi, the bias current ought to be increased to 50mA. Ideally, you would use better (faster / more linear) output transistors as well, but even with those specified the amp performs well indeed. This is largely because they are run at comparatively low power, and the extreme non-linearity effects would expect with only transistors do not occur because of the parallel output stage.

Make positive that the bias transistor is attached to of the drivers (the PCB is laid out to make this simple to do). A some quantity of heat sink compound as well as a cable tie will do the job well. The diodes are there to protect the amp from catastrophic failure ought to the bias servo be incorrectly wired (or set for maximum current). All diodes ought to be 1N4001 (or 1N400? - anything in the 1N400x range is fine). A heat sink is not needed for any of the driver transistors.

The life of a guitar amp is a hard, and I recommend that you use the largest heat sink you can afford, since it is common to have elevated temperatures on stage (chiefly due to all the lighting), and this reduces the safety margin that normally applies for domestic equipment. The heat sink ought to be rated at 0.5° C/Watt to permit for worst case long term operation at up to 40°C (this is not unusual on stage).

Make sure that the speaker connectors are isolated from the chassis, to keep the integrity of the earth isolation parts in the power supply, & to make sure that the high impedance output is maintained.
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Wiring Diagrams Auspex Creative Flow Australia

Wiring Diagram on Bodine Electric Motor Wiring Doityourself Com Community Forums
Bodine Electric Motor Wiring Doityourself Com Community Forums.


Wiring Diagram on Wiring Diagrams Auspex Creative Flow Australia
Wiring Diagrams Auspex Creative Flow Australia.


Wiring Diagram on Hampton Bay Ceiling Fan Wiring Diagram Group Picture Image By Tag
Hampton Bay Ceiling Fan Wiring Diagram Group Picture Image By Tag.


Wiring Diagram on Wiring Diagram Trailer Wiring Troubleshooting Trailer Wiring Diagrams
Wiring Diagram Trailer Wiring Troubleshooting Trailer Wiring Diagrams.


Wiring Diagram on Dodge Dakota Radio Wiring Diagram 1998 Dodge Ram 1500 Wiring Diagram
Dodge Dakota Radio Wiring Diagram 1998 Dodge Ram 1500 Wiring Diagram.


Wiring Diagram on 1964 Gmc Truck Electrical System Wiring Diagram Circuit Schematic
1964 Gmc Truck Electrical System Wiring Diagram Circuit Schematic.


Wiring Diagram on Wiring Diagram 1995 Chevy Tahoe Wiring Diagram
Wiring Diagram 1995 Chevy Tahoe Wiring Diagram.


Wiring Diagram on Wiring Diagram For Push Button Mag Starter Control
Wiring Diagram For Push Button Mag Starter Control.


Wiring Diagram on Honda Odyssey Horn Circuit Wiring Diagram
Honda Odyssey Horn Circuit Wiring Diagram.


Wiring Diagram on Series 600 Electric Wiring Diagram Car Parts And Wiring Diagram
Series 600 Electric Wiring Diagram Car Parts And Wiring Diagram.


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Wednesday, April 10, 2013

Powerful Security Siren

Simple circuit - No ICs required, 12V Battery operation

This circuit was requested by several correspondents. Its purpose was to obtain more power than the siren circuit already available on this website (One-IC two-tones Siren) and to avoid the use of ICs. A complementary transistor pair (Q2 & Q3) is wired as a high efficiency oscillator, directly driving the loudspeaker. Q1 ensures a full charge of C2 when power is applied to the circuit. Pressing on P1, C2 gradually discharges through R8: the circuit starts oscillating at a low frequency that increases slowly until a high steady tone is reached and kept indefinitely. When P1 is released, the output tone frequency decreases slowly as C2 is charged to the battery positive voltage through R6 and the Base-Emitter junction of Q2. When C2 is fully charged the circuit stops oscillating, reaching a stand-by status.

Powerful Security Siren Circuit diagram:

Powerful Security Siren
Parts:

P1 = SPST Pushbutton Operating Switch
R1 = 1K
R2 = 10K
R3 = 1K
R4 = 220R
R5 = 10K
R6 = 220K
R7 = 22K
R8 = 100K
C1 = 22uF-25V
C2 = 22uF-25V
C3 = 10nF-63V
C4 = 47uF-25V
Q1 = BC557
Q2 = BC557
Q3 = BC337
B1 = 12V Battery
SW1 = SPST Toggle or Slide Main Switch
SPKR = 8 Ohms Loudspeaker

  Notes:
  • A good sized loudspeaker will ensure a better and powerful output tone.
  • As stand-by current drawing is zero, SW1 can be omitted and B1 wired directly to the circuit.
  • Maximum current drawing at full output is about 200mA.
Source :  http://www.ecircuitslab.com/2011/05/powerful-security-siren.html


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Ultra Simple Microphone Preamplifier

This little project came about as a result of a design job for a client. One of the items needed was a mic preamp, and the project didnt warrant a design such as the P66 preamp, since it is intended for basic PA only. Since mic preamps are needed by people for all manner of projects, this little board may be just whats needed for interfacing a balanced microphone with PC sound cards or other gear. Unlike most of my boards, this one is double-sided. I normally avoid double-sided PCBs for projects because rework by those inexperienced in working with them will almost certainly damage the board beyond repair.

I consider this not to be an issue with this preamp, because it is so simple. It is extremely difficult to make a mistake because of the simplicity. As you can see, the board uses a PCB mounted XLR connector and pot, so is a complete mic preamp, ready to go. Feel free to ignore the terminals marked SW1 (centred between the two electrolytic supply caps), as they are specific to my clients needs and are not useful for most applications. The original use was to use them for a push-button switch that activated an audio switch via a PIC micro-controller. They are not shown on the schematic.

Ultra-Simple Microphone Preamplifier Image Project :
 P12-pic
The DC, GND and output terminals may be hard wired to the board, you may use PCB pins or a 10-way IDC (Insulation Displacement Connector) and ribbon cable. Power can be anything between +/-9V and +/-18V with an NE5532 opamp. The mic input is electronically balanced, and noise is quite low if you use the suggested opamp. Gain range is from about 12dB to 37dB as shown. It can be increased by reducing the value of R6, but this should not be necessary. Because anti-log pots are not available, the gain control is not especially linear, but unfortunately in this respect there is almost no alternative and the same problem occurs with all mic preamps using a similar variable gain control system.

Ultra-Simple Microphone Preamplifier Circuit diagram:

P12-f1

The circuit is quite conventional, and if 1% metal film resistors are used throughout it will have at least 40dB of common mode rejection with worst-case values. The input capacitors give a low frequency rolloff of -3dB at about 104Hz. If better low frequency response is required, these caps may be increased to 4.7uF or 10uF bipolar electrolytics. These will give response to well below 10Hz if you think youll ever need to go that low. The project PCB measures 77 x 24mm, and the mounting centers for the pot and XLR connector are spaced at 57mm. If preferred, a traditional chassis mounted female XLR can be used, and wired to the board with heavy tinned copper wire. The PCB pads for the connector are in the correct order for a female chassis mount socket mounted with the "Push" tab at the top.

source:  http://www.ecircuitslab.com/2011/08/ultra-simple-microphone-preamplifier.html
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Non Contact Power Monitor

Here is a simple non-contact AC power monitor for home appliances and laboratory equipment that should remain continuously switched-on. A fuse failure or power breakdown in the equipment going unnoticed may cause irreparable loss. The monitor sounds an alarm on detecting power failure to the equipment. The circuit is built around CMOS IC CD4011 utilising only a few components. NAND gates N1 and N2 of the IC are wired as an oscillator that drives a piezobuzzer directly. Resistors R2 and R3 and capacitor C2 are the oscillator components. The amplifier comprising transistors T1 and T2 disables the oscillator when mains power is available. In the standby mode, the base of T1 picks up 50Hz mains hum during the positive half cycles of AC and T1 conducts.

Non-Contact Power Monitor Circuit diagram:  
    Non-Contact Power Monitor circuit diagram

This provides base current to T2 and it also conducts, pulling the collector to ground potential. As the collectors of T1 and T2 are connected to pin 2 of NAND gate N1 of the oscillator, the oscillator gets disabled when the transistors conduct. Capacitor C1 prevents rise of the collector voltage of T2 again during the negative half cycles. When the power fails, the electrical field around the equipment’s wiring ceases and T1 and T2 turn off. Capacitor C1 starts charging via R1 and preset VR and when it gets sufficiently charged, the oscillator is enabled and the piezobuzzer produces a shrill tone. Resistor R1 protects T2 from short circuit if VR is adjusted to zero resistance.

The circuit can be easily assembled on a perforated/breadboard. Use a small plastic case to enclose the circuit and a telescopic antenna as aerial. A 9V battery can be used to power the circuit. Since the circuit draws only a few microamperes current in the standby mode, the battery will last several months. After assembling the circuit, take the aerial near the mains cable and adjust VR until the alarm stops to indicate the standby mode. The circuit can be placed on the equipment to be monitored close to the mains cable.

Source : http://www.ecircuitslab.com/2011/06/non-contact-power-monitor-circuit.html
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