Showing posts with label using. Show all posts
Showing posts with label using. Show all posts
Tuesday, September 24, 2013
Infra red Light Barrier Using 555
This is a short-range light barrier for use as an intruder alarm in doorposts, etc. The 555 in the transmitter (Figure 1) oscillates at about 4.5 kHz, supplying pulses with a duty cycle of about 13% to keep power consumption within reason. Just about any infra-red LED (also called IRED) may be used. Suggested, commonly available types are the LD271 and SFH485. The exact pulse frequency is adjusted with preset P1. The LEDs are pulsed at a peak current of about 100 mA, determined by the 47 Ω series resistor. In the receiver (Figure 2), the maximum sensitivity of photo-diode D2 should occur at the wavelength of the IR LEDs used in the transmitter. You should be okay if you use an SFH205F, BPW34 or BP104. Note that the photo-diode is connected reverse-biased! So, if you measure about 0.45 V across this device, it is almost certainly fitted the wrong way around.
The received pulses are first amplified by T1 and T2. Next comes a PLL (phase lock loop) built with the reverenced NE567 (or LM567). The PLL chip pulls its output, pin 8, Low when it is locked onto the 4.5 kHz ‘tone’ received from the transmitter. When the (normally invisible) light beam is interrupted (for example, by someone walking into the room), the received signal disappears and IC1 will pull its output pin High. This enables oscillator IC2 in the receiver, and an audible alarm is produced. The two-transistor amplifier in the receiver is purposely over-driven to some extent to ensure that the duty cycle of the output pulses is roughly 50%.
If the transmitter is too far away from the receiver, over-driving will no longer be guaranteed, hence IC1 will not be enabled by an alarm condition. If you want to get the most out of the circuit in respect of distance covered, start by modifying the value of R2 until the amplifier output signal again has a duty cycle of about 50%. The circuit is simple to adjust. Switch on the receiver, the buzzer should sound. Then switch on the transmitter. Point the transmitter LEDs to the receiver input. Use a relatively small distance, say, 30 cm. Adjust P1 on the transmitter until the buzzer is silenced. Switch the receiver off and on again a few times to make sure it locks onto the transmitter carrier under all circumstances. If necessary, re-adjust P1, slowly increasing the distance between the transmitter and the receiver.
See More Detail[...]
The received pulses are first amplified by T1 and T2. Next comes a PLL (phase lock loop) built with the reverenced NE567 (or LM567). The PLL chip pulls its output, pin 8, Low when it is locked onto the 4.5 kHz ‘tone’ received from the transmitter. When the (normally invisible) light beam is interrupted (for example, by someone walking into the room), the received signal disappears and IC1 will pull its output pin High. This enables oscillator IC2 in the receiver, and an audible alarm is produced. The two-transistor amplifier in the receiver is purposely over-driven to some extent to ensure that the duty cycle of the output pulses is roughly 50%.
If the transmitter is too far away from the receiver, over-driving will no longer be guaranteed, hence IC1 will not be enabled by an alarm condition. If you want to get the most out of the circuit in respect of distance covered, start by modifying the value of R2 until the amplifier output signal again has a duty cycle of about 50%. The circuit is simple to adjust. Switch on the receiver, the buzzer should sound. Then switch on the transmitter. Point the transmitter LEDs to the receiver input. Use a relatively small distance, say, 30 cm. Adjust P1 on the transmitter until the buzzer is silenced. Switch the receiver off and on again a few times to make sure it locks onto the transmitter carrier under all circumstances. If necessary, re-adjust P1, slowly increasing the distance between the transmitter and the receiver.
Wednesday, May 1, 2013
Simple Subwoofer Lowpass Filter using uA741 Single Op Amp Ic
This is the simplest Sub woofer Low Pass filter Circuit using uA741 single op amp ic. The circuit is very low cost with respect to their work. The cut off frequency of this circuit is 25Hz to 80Hz maximum. Using this circuit , you can easily design a 2.1 Sub-woofer Speaker System at your own Home. The circuit contains very few components.In Pakistan, the cost of this circuit with PCB is Rs:45 The same circuit is working in my own hand made sub-woofer system.
R1,R3,R4 = 10K 1/4W
R2=100K 1/4W
CY1,CY2 = 0.22uF Polyester
C1,C2 = 10uF/25V Electrolytic
IC1 = uA741A Single Op-Amp Ic + 8 Pin Ic Socket
3 Pin Male & Female Connector x 2
2 Pin Male & Female Connector x 1
PCB as in required size 4.5 cm x 3.4 cm
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
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.
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.
Friday, April 12, 2013
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.
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.
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:
| 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
Saturday, April 6, 2013
LED Tube Light Using Transformer Circuit Diagram
Using white LEDs for illuminating our homes is becoming popular nowadays, due to the high power efficiency involved with these devices. The diagram shows a straightforward configuration involving many LEDs, arranged in series and parallel.The LEDs are driven by a general purpose 24 V power supply for illuminating the LED bank very brightly. The power supply incorporates standard bridge and capacitor network for the required rectification and filtration of the supply voltage to the LEDs.
The arrangement of the LEDs is done in the following way:
The supply voltage being 24, dividing it by the forward voltage of a white LED which is around 3 volts gives 24/3 = 6, meaning the supply voltage will be able to support at the most 6 LEDs in series.
However since we are interested to include many LEDs (132 here), we need to connect many of these series connected strings of LED through parallel connections.
Thats exactly what we do here.
Total 22 strings of LEDs having 6 in each are connected in parallel, as shown in the figure.
Since current limiting becomes an important issue with the white LEDs, a limiting resistor is added in series with each of the strings. The value of the resistor may be optimized by the user for adjusting the overall illumination of the LED tube light.
The proposed design will provide enough light for illuminating a small 10 by 10 room brightly, and will consume not more than 0.02 * 22 = 0.44 Amps or 0.44 * 24 = 10.56 watts of power.
24 Volt, LED Tube Light Using Transformer, Circuit Diagram
Subscribe to:
Posts (Atom)