Friday, December 27, 2013
DC 1 3V to 22V Adjustable Regulator
This compact regulator PCB can be used to produce a fully regulated DC supply ranging from 1.3V to 22V at currents up to 1A. Depending on how much current you need, it can fit into tiny spaces and is easily connected with 2-pin headers for DC input, DC output, an on/off switch and a LED. There are many fixed-voltage IC regulators available such as those with 5V, 6V 8V, 9V, 12V & 15V outputs.
But what if you want a voltage output that does not fit into one of the standard ranges or if you want to be able to easily adjust this output voltage? The MiniReg is the answer: it can be set to provide the exact voltage you require. It is based on an LM317T 3-terminal regulator. The PCB has only a few other components: three diodes, three capacitors, two resistors and a trimpot to set the output voltage from the regulator.
Diagram shows the circuit details. The LM317T adjustable regulator provides a nominal 1.25V between its OUT and ADJ (adjust) terminals. The output voltage from REG1 is set by the 110O resistor (R1) between the OUT and ADJ terminals and by the resistance between the ADJ terminal and ground. This works as follows: by using a 110O resistor and assuming an exact 1.25V reference, the current flow is set at 11.36mA. This is calculated by dividing the voltage between the OUT and ADJ terminals (1.25V) by the 110O resistor.
This current also flows through trimpot VR1. This means that if VR1 is set to a value of 1kO , then the voltage across this resistor will be 1kO x 11.36mA or 11.36V. This voltage is then added to the 1.25V reference to derive the output voltage ñ in this case 12.61V. In practice, the current flow out of the ADJ terminal also contributes slightly to the final output voltage. This current is of the order of 100µA. So if VR1 is set to 1kO , this can add 0.1V to the output, ie, we get 12.71V.
If you are interested in the output voltage equation, then it is:
VOUT = VREF(1 + R1/R2) + IADJ x R2
where VOUT is the output voltage, VREF is the voltage between the OUT and ADJ terminals and IADJ is the current out of the ADJ terminal (typically 50µA but as high as 100µA). R1 is the resistance between the OUT and ADJ terminals, while R2 is the resistance between the ADJ terminal and ground. Diode D1 in series with the input provides reverse polarity protection. This means that if you connect the supply voltage around the wrong way, you cannot do any damage.
Diode D2 protects the regulator if the input becomes shorted to ground while it is powered up. Without D2, current would attempt to flow back from the output capacitor through the regulator to the shorted input and that could kill it. But D2 becomes forward biased and conducts, effectively preventing any reverse current flow through REG1.
Diode D3 is also included to protect REG1. It does this by clamping the voltage between the ADJ terminal and the OUT & IN terminals in the event that one of the latter is shorted to ground. Finally, capacitors C1 & C2 reduce ripple and noise by bypassing the IN (input) and ADJ terminals respectively. C3 prevents regulator oscillation by swamping any low-value capacitance that may be connected to this output.
See More Detail[...]
But what if you want a voltage output that does not fit into one of the standard ranges or if you want to be able to easily adjust this output voltage? The MiniReg is the answer: it can be set to provide the exact voltage you require. It is based on an LM317T 3-terminal regulator. The PCB has only a few other components: three diodes, three capacitors, two resistors and a trimpot to set the output voltage from the regulator.
 |
| DC 1.3V to 22V Power Supply Circuit Diagram |
Diagram shows the circuit details. The LM317T adjustable regulator provides a nominal 1.25V between its OUT and ADJ (adjust) terminals. The output voltage from REG1 is set by the 110O resistor (R1) between the OUT and ADJ terminals and by the resistance between the ADJ terminal and ground. This works as follows: by using a 110O resistor and assuming an exact 1.25V reference, the current flow is set at 11.36mA. This is calculated by dividing the voltage between the OUT and ADJ terminals (1.25V) by the 110O resistor.
This current also flows through trimpot VR1. This means that if VR1 is set to a value of 1kO , then the voltage across this resistor will be 1kO x 11.36mA or 11.36V. This voltage is then added to the 1.25V reference to derive the output voltage ñ in this case 12.61V. In practice, the current flow out of the ADJ terminal also contributes slightly to the final output voltage. This current is of the order of 100µA. So if VR1 is set to 1kO , this can add 0.1V to the output, ie, we get 12.71V.
If you are interested in the output voltage equation, then it is:
VOUT = VREF(1 + R1/R2) + IADJ x R2
where VOUT is the output voltage, VREF is the voltage between the OUT and ADJ terminals and IADJ is the current out of the ADJ terminal (typically 50µA but as high as 100µA). R1 is the resistance between the OUT and ADJ terminals, while R2 is the resistance between the ADJ terminal and ground. Diode D1 in series with the input provides reverse polarity protection. This means that if you connect the supply voltage around the wrong way, you cannot do any damage.
Diode D2 protects the regulator if the input becomes shorted to ground while it is powered up. Without D2, current would attempt to flow back from the output capacitor through the regulator to the shorted input and that could kill it. But D2 becomes forward biased and conducts, effectively preventing any reverse current flow through REG1.
Diode D3 is also included to protect REG1. It does this by clamping the voltage between the ADJ terminal and the OUT & IN terminals in the event that one of the latter is shorted to ground. Finally, capacitors C1 & C2 reduce ripple and noise by bypassing the IN (input) and ADJ terminals respectively. C3 prevents regulator oscillation by swamping any low-value capacitance that may be connected to this output.
Thursday, December 26, 2013
USB Powered Audio Power Amplifier
This circuit of multimedia speakers for PCs has single-chip-based design, low-voltage power supply, compatibility with USB power, easy heat-sinking, low cost, high flexibility and wide temperature tolerance. At the heart of the circuit is IC TDA2822M. This IC is, in fact, mono-lithic type in 8-lead mini DIP package. It is intended for use as a dual audio power amplifier in battery-powered sound players. Specifications of TDA2822M are low quiescent current, low crossover distortion, supply voltage down to 1.8 volts and minimum output power of around 450 mW/channel with 4-ohm loudspeaker at 5V DC supply input.
An ideal power amplifier can be simply defined as a circuit that can deliver audio power into external loads without generating significant signal distortion and without consuming excessive quiescent current. This circuit is powered by 5V DC supply available from the USB port of the PC. When power switch S1 is flipped to ‘on’ position, 5V power supply is extended to the circuit and power-indicator red LED1 lights up instantly. Resistor R1 is a current surge limiter and capacitors C1 and C4 act as buffers. Working of the circuit is simple. Audio signals from the PC audio socket/headphone socket are fed to the amplifier circuit through components R2 and C2 (left channel), and R3 and C3 (right channel)
USB Powered Audio Power Amplifier Circuit diagram:
Potmeter VR1 works as the volume controller for left (L) channel and potmeter VR2 works for right (R) channel. Pin 7 of TDA2822M receives the left-channel sound signals and pin 6 receives the right-channel signals through VR1 and VR2, respectively. Ampl i f ied signals for driving the left and right loudspeakers are available at pins 1 and 3 of IC1, respectively. Components R5 and C8, and R6 and C10 form the traditional zobel network. Assemble the circuit on a medium-size, general-purpose PCB and enclose in a suitable cabinet. It is advisable to use a socket for IC TDA2822M. The external connections should be made using suitably screened wires for better result.
Sucre: http://www.ecircuitslab.com/2011/06/usb-powered-audio-power-amplifier.html
Wednesday, December 25, 2013
Sub Woofer and Controller Circuit Diagram
Sub woofers are popular, with home theater being of the driving forces. However, a nice sub adds considerably to normal hi-fi program material, & so if it is predictable & has nice response characteristics.
all of sub woofers use a immense speaker driver in a immense box, with tuning vents & all the difficulties (& vagaries) that conventional operation entails. By conventional, I mean that the speaker & cabinet are operated as a resonant technique, using the Thistle-Small parameters to get a box which will (if everything works as it ought to) provide excellent performance.
all of sub woofers use a immense speaker driver in a immense box, with tuning vents & all the difficulties (& vagaries) that conventional operation entails. By conventional, I mean that the speaker & cabinet are operated as a resonant technique, using the Thistle-Small parameters to get a box which will (if everything works as it ought to) provide excellent performance.
Completed Prototype
A fast word is warranted here, to let you decide if the speaker you have will actually work in a little sealed enclosure. The EAS principle will permit any driver to extend to twenty Hz or even lower. A lovely fast check is to stick the speaker in a box, and drive it to 100W or so at twenty Hz - you ought to see lots of cone movement, a few things will rattle, but you should not actually listen to a tone. A "bad" speaker will generate 60 Hz (third harmonic) - in the event you dont listen to anything, the speaker will work in an equalized sub.
If a tone is audible, or the speaker shows any signs of distress (such as the cone breaking up with appropriate terrible noises), then the driver cannot be used in this manner. Either discover a different driver, or use a vented enclosure.
Before you can build your own EAS box, you will require to pick an appropriate driver, using the above as a guide. Cone tour will be high at the lowest frequencies, so the speaker needs to be able to high power, lovely tour, & of reasonable size (there is no substitute for cone area for moving air at low frequencies). I am using a 380mm (15") driver, but smaller drivers (say 300mm - 12") can be used, or even a bigger number of smaller drivers. I have also had excellent results with a single 300mm driver, which has lower sensitivity (as would expect) but is perfectly adequate for normal usage.
The check methods I used are applicable to any combination, but in general I recommend either a single giant driver or a pair of (say) 300mm units. The next hurdle is the amplifier needed to drive the speaker. This is not trivial. If the selected driver has a sensitivity of 93dB / W @ one metre, then you can safely assume that the efficiency will be less than this below resonance, by a factor of possibly 6dB or more. In case you are used to driving a sub with 100W, this means that you have increased the power to 400W - although this is an over-simplification.
If they are to operate the sub from 60Hz (my aim from the outset), they will increase the power by 12dB for each octave, so if 20W is necessary at 60Hz, then at 30Hz this has increased to 320W, & at 15Hz, you will require over 5kW.
Fortunately, the reality is a tiny different, & 400W or so will be over sufficient for a powerful process, due chiefly to the fact that the energy content in the low bass region is not normally all that great. (Although some program material may have high energy content, in general this is not the case). The EAS process augments the existing process, which is allowed to roll off naturally - contrast this with the normal case, where a crossover is used to separate the low bass from the main process, so existing speaker capability is lost.
The box I built is made from 25mm (1") MDF (Medium Density Fiberboard), & filled with fiberglass. Apart from the fact that it is very heavy (which is a lovely thing, because it desires to walk with low frequencies), the cabinet is acoustically dead, with no resonances in the low frequencies at all ( unlike my house & furniture, dammit !). The woofer is recessed in to the baffle, & sealed with weather sealing foam. When attaching the speaker, do NOT use wood screws, or any other screw in to the MDF. I used "Tee" nuts. I have no idea what they are called elsewhere in the world, but they look like this
TEE NUT
The middle is tapped, and accepts a metal thread screw, and the small spikes mean that you must drill a hole, and hammer in the Tee nut. In case you use a screw through the hole and screwed lightly in to the Tee nut, you can hold it in place as you bash away at it, and can also see that it is straight when you are done. make sure that the finish of the screw doesnt stick out the finish, or you will seldom remove it again after the hammering! I recommend that you lock the tee nut in to place with some construction adhesive (dont get any in the threaded section) so they dont fall out while you are installing the speaker.
The EAS Controller
The controller is (actually very) simple, & the circuit is shown in Figure one. An input buffer ensures that the input impedance of the source does not affect the integrator performance, & allows summing of left & right channels without any crosstalk. The output provides a phase reversal switch, so that the sub can be properly phased to the remainder of the process. If the mid-bass disappears as you advance the level control, then the phase is wrong, so switch to the opposite position.
The controller is (actually very) simple, & the circuit is shown in Figure one. An input buffer ensures that the input impedance of the source does not affect the integrator performance, & allows summing of left & right channels without any crosstalk. The output provides a phase reversal switch, so that the sub can be properly phased to the remainder of the process. If the mid-bass disappears as you advance the level control, then the phase is wrong, so switch to the opposite position.
Figure 1 - The Original EAS Filter / Controller
It turns out that the controller can be simplified, but there is no point. While the dual pot appeared like a lovely suggestion when I built my unit, it actually only changes the gain. Now, having experimented some more, this is an excellent thing, since it means that the level through the controller can be set to make positive that there is no distortion - there can be a immense amount of gain at low frequencies, & if the gain is high, distortion is assured!
The integrators (U1B & U2A) include shelving resistors (R6 & R9), & the capacitor / resistor networks (C1-R4, C3-R7) be positive that signals below 20Hz are attenuated. In case you dont require to go that low, then the worth of the caps (or the resistors R4 & R7) can be reduced. I used four.7uF caps, & these are non-polarized electrolytic - a high value was needed to keep the impedance low to the integrators. I originally included the dual pot (VR1) to permit the upper frequency roll off to be set - however it does no such thing (as described above). The final output level is set with VR2, which may be left out if your power amp has a level control.
The integrators (U1B & U2A) include shelving resistors (R6 & R9), & the capacitor / resistor networks (C1-R4, C3-R7) be positive that signals below 20Hz are attenuated. In case you dont require to go that low, then the worth of the caps (or the resistors R4 & R7) can be reduced. I used four.7uF caps, & these are non-polarized electrolytic - a high value was needed to keep the impedance low to the integrators. I originally included the dual pot (VR1) to permit the upper frequency roll off to be set - however it does no such thing (as described above). The final output level is set with VR2, which may be left out if your power amp has a level control.
It is OK to substitute different op amps, but there is tiny reason to do so. Any substitution tool ought to be a FET input op amp, or DC offset may be an issue. Do not be tempted to make use of a DC coupled amp. If the you are planning to make use of is DC coupled, the input ought to be isolated with a capacitor. Pick a value to give a -3dB frequency of about 10Hz, as this will have tiny effect on the low frequency response, but will help to attenuate the subsonic frequencies.
The unity gain range (using a 20k pot as shown) is from 53Hz to 159Hz. This ought to be sufficient for most systems, but if desired, the resistors (R5 & R8) can be increased in value to 22k, or you can select a bigger value pot. Using 22k resistors & the 20k pot will give a range from 36Hz to 72Hz.
The unity gain range (using a 20k pot as shown) is from 53Hz to 159Hz. This ought to be sufficient for most systems, but if desired, the resistors (R5 & R8) can be increased in value to 22k, or you can select a bigger value pot. Using 22k resistors & the 20k pot will give a range from 36Hz to 72Hz.
To permit lower frequencies, you can increase the 100k shelving resistors (R6 and R9) to 220k, and increase the high pass capacitors (four.7uF) with 10uF (or R4 & R7 may be increased - a maximum of four.7k is recommended). This will give a turnover frequency of around 8Hz, but expect to make use of much more power, as there will likely be significant sub-sonic energy that will generate huge cone excursions with no audible benefit.
The input must be a standard full range (or for a stampeded method, the whole low frequency signal). Do not use a crossover or other filter before the EAS controller. For final modification, and to integrate the method in to your listening room, I recommend the constant-Q equalizer. The final result using this is extraordinarily nice - I have flat in-room response to 20Hz!
The input must be a standard full range (or for a stampeded method, the whole low frequency signal). Do not use a crossover or other filter before the EAS controller. For final modification, and to integrate the method in to your listening room, I recommend the constant-Q equalizer. The final result using this is extraordinarily nice - I have flat in-room response to 20Hz!
For the power supply, use the in anything else will provide +/-15V at a few Milli amps. My supply is not even regulated, & the whole method is as close to noiseless as you will listen to (or not listen to). Construction is not critical - I built mine on a piece of Overboard (perforated prototype board), & managed to fit everything (including the power supply rectifier & filter) on a piece about 100 x 40 millimeters with room to spare.
The EAS method is surprisingly simple to set up with no instrumentation. Of coursework in case you have an SPL meter & oscillator you can also confirm the settings with measurements. Keep in mind that the room acoustics will play havoc with the results, so unless you require to drag the whole method outside, setting by ear might be the simplest. Even in case you did get it exactly right in an anechoic surroundings, this would alter one time it was in your listening room anyway.
It takes a small experimentation to get right, but is surprisingly simple to do. When properly set, a check track (or bass guitar) ought to be smooth from the highest bass note to the lowest, with no gross peaks or dips. Some are inevitable because of room resonances & the like, but you will discover a setting that sounds "right" with small difficulty.
The EAS method is surprisingly simple to set up with no instrumentation. Of coursework in case you have an SPL meter & oscillator you can also confirm the settings with measurements. Keep in mind that the room acoustics will play havoc with the results, so unless you require to drag the whole method outside, setting by ear might be the simplest. Even in case you did get it exactly right in an anechoic surroundings, this would alter one time it was in your listening room anyway.
It takes a small experimentation to get right, but is surprisingly simple to do. When properly set, a check track (or bass guitar) ought to be smooth from the highest bass note to the lowest, with no gross peaks or dips. Some are inevitable because of room resonances & the like, but you will discover a setting that sounds "right" with small difficulty.
Performance Of My Prototype
I measured 80dB SPL at one meter in my workshop (sub-woofer perched on a chair in more or less the middle of the space) with at 25Hz & 70W. This improved dramatically when the unit was installed in the listening room, but as I said earlier, there is usually not a lot recorded below around 35Hz. The longest pipe on the organ is usually about 16Hz, but larger pipes still may be used. It was found necessary to cease group of diapasons (able to 8Hz) in the famous Sydney Town Hall organ because when they were used, the very low frequency caused building destroy.
I measured 80dB SPL at one meter in my workshop (sub-woofer perched on a chair in more or less the middle of the space) with at 25Hz & 70W. This improved dramatically when the unit was installed in the listening room, but as I said earlier, there is usually not a lot recorded below around 35Hz. The longest pipe on the organ is usually about 16Hz, but larger pipes still may be used. It was found necessary to cease group of diapasons (able to 8Hz) in the famous Sydney Town Hall organ because when they were used, the very low frequency caused building destroy.
A couple of orchestral recordings revealed traffic (or perhaps underground railway) rumble that I was unaware of before (however this was before it was set correctly, and the bass was a tad louder than needed). One time set up properly, its presence is unobtrusive - except I now have about and a half octaves of additional bottom finish.
I finally decided on a 20Hz maximum frequency (-3dB), and this is reflected in the part values shown in Figure one. The actual roll-over frequency is 16.5Hz, after which the output is attenuated at about 12dB / octave (see Figure two). Without the roll off capacitors, the gain would be 20dB at 20Hz. Unity gain frequencies are about 4Hz and 63Hz with the 20k pot(s) centered.
Figure 2 - Frequency Response of EAS Controller
awesome Australian readers may recognize the woofer brand in the picture (Figure three) of my done unit. The compact size of the box can be seen from the fact that there is tiny spacing around the speaker itself, and most of what is there is the top and sides - I used 25mm MDF, so it makes the outside of the box a bit bigger than the inside. Outside dimensions are 470W x 450H x 410D (18 1/2"W x 17 1/2"H x 16"D), which gives a capacity of 60 liters (about two.1 ft³ - excluding the internal space occupied by the speaker. I think you would agree that this is a small box indeed for a 380mm loudspeaker that performs down to 15Hz.
Figure 3 - Photo of Completed EAS Cabinet
Overall, I would must say that I doubt that any conventional design would be as compact, or would have such clarity & solidarity. Being a sealed box, there is not of the "waffle" that ported designs often give, & the speaker is protected against excessive tour by the air pressure in the box itself (below the cutoff frequency, anyway).
The bottom finish in my technique is now staggering. It is rock solid, & absolutely thunders when called on. The 400W amp is over sufficient for the job, thinking about its to keep up with a biamped main technique able to high SPL (up to 120dB at my listening position). In fact a fast check indicates that 200W would have been (but . better to have it & not require it than require it & not have it).
The fact that the EAS design augments the existing speakers than taking over from them with a crossover goes a long way towards ensuring the power requirements do not get out of hand. As an added benefit, I have found that I get the same aural sensation at much lower SPLs - I can listen happily at 90dB, but it sounds much louder. I may even listen to the phone ring while listening now !
All in all, I feel it is unlikely that anything other than an isobaric enclosure could give the same performance for a box size even close to the EAS box,& even then would be limited to about 35Hz. Added to this is the unpredictable combined response of the main speakers and the sub, which is not an Problem with this design. With an EAS system, more power is necessary than a standard design, but for plenty of people, power is less costly than space.
Tuesday, December 24, 2013
Simple Solar Cell Voltage Regulator Circuit Diagram
This is a Simple Solar Cell Voltage Regulator Circuit Diagram. This device is designed to be a simple, inexpensive ‘comparator’, intended for use in a solar cell power supply setup where a quick ‘too low’ or ‘just right’ voltage indicator is needed. The circuit consists only of one 5V regulator, two transistors, two LEDs, five resistors, two capacitors, and one small battery. Although a 4-V battery is indicated, 4.5 V (3 alkalines in series) or 3.6 V (3 NiCd cells in series) will also work.
Solar Cell Voltage Regulator Circuit Diagram
The specifications of voltage regulator IC1 are mainly determined by the size and number of the solar cells and the current pull of the equipment connected to the output. Here the low-drop 4805 is suggested but other regulators may work equally well as long as you observe the output voltage of the solar cells. Transistors T1 and T2 are complementary types i.e. one each of the pnp and npn variety.
Although the ubiquitous BC557B (pnp) and BC547B (npn) are indicated, any small-signal equivalents out of the junk box will probably do. The values of voltage dividers R1/R6 and R3/R4 may need to be adjusted according to the type of transistor and its gain, or according to the desired voltage thresholds. Using the resistor values shown in the schematic, LED D2 turns on fully when the voltage is just above 5 volts.
LED D1 turns on when the voltage drops below 4.2 volts or so. Between those two thresholds, there is a sort of no man’s land where both LEDs are on dimly. A buzzer or other warning device could be connected across the terminals of LED D1 to give a more substantial warning if the voltage drops below operating limits. The current consumption of the circuit is about 20 mA at 5 V, and it decreases with the voltage supplied by the solar cells.
Sunday, December 22, 2013
Miniature USB Powered Amplifier for Laptops
There’s been a strategy in market of buying USB powered speakers for laptops. These speakers usually drives power from one available USB port and inputs audio signal from headphone port, thus consuming two ports of a notebook. Lets see how much output these kind of speakers can give.
A USB port delivers maximum 500mA current and at 5Volts, it comes to max 0.5×5=2.5Watts. So, if our circuit eats 0.5-1Watts power, only 1.5Watt is left for speakers output. Now you might ask 1.5watt wouldn’t create much sound. But believe me, under good conditions, this 1.5Watts is much more than expected. And this time we are going to use 0.5Watt-4Ohm x 2nos speakers.
These speakers are flat type having magnet inside them, and available at wholesale electronics shop in around 30rs per piece. For speaker box, use old jumbo matches box like homelite box. And for circuit, you need is an audio amplifier circuit capable of giving 0.5Watt output at each channel.
Here we will use a general purpose stereo amplifier TDA2822M IC, which comes in 8pin DIP package and usually found in mini walk-mans, etc. This IC can give up to 450 mW/channel with 4-ohm loudspeaker at 5V supply which is near our requirement.
The datasheet of TDA2822M can be downloaded in PDF format here (PDF, 362KB). The expense in making this circuit is no more than 25 rupees. Hence the total cost becomes 30+30+25=85rupees, and if we add the cost of wires, jacks etc then it well fits under 100rupees. It’s a very cheap solution when USB speakers in market costs more than 300 rupees.
See More Detail[...]
A USB port delivers maximum 500mA current and at 5Volts, it comes to max 0.5×5=2.5Watts. So, if our circuit eats 0.5-1Watts power, only 1.5Watt is left for speakers output. Now you might ask 1.5watt wouldn’t create much sound. But believe me, under good conditions, this 1.5Watts is much more than expected. And this time we are going to use 0.5Watt-4Ohm x 2nos speakers.
These speakers are flat type having magnet inside them, and available at wholesale electronics shop in around 30rs per piece. For speaker box, use old jumbo matches box like homelite box. And for circuit, you need is an audio amplifier circuit capable of giving 0.5Watt output at each channel.
Here we will use a general purpose stereo amplifier TDA2822M IC, which comes in 8pin DIP package and usually found in mini walk-mans, etc. This IC can give up to 450 mW/channel with 4-ohm loudspeaker at 5V supply which is near our requirement.
The datasheet of TDA2822M can be downloaded in PDF format here (PDF, 362KB). The expense in making this circuit is no more than 25 rupees. Hence the total cost becomes 30+30+25=85rupees, and if we add the cost of wires, jacks etc then it well fits under 100rupees. It’s a very cheap solution when USB speakers in market costs more than 300 rupees.
Saturday, December 21, 2013
The signal jammer is what increases the signal
The external directional antenna is designed to pick up the weak signal that is being broadcast by your cellular provider.
The signal the external antenna picks up is sent over wires to the signal jammer. The signal jammer is what increases the signal. Your boosted signal is then sent to the internal antenna which wirelessly rebroadcasts a more powerful signal within your space.
Cell blocker operate on different frequencies: 800 MHz, 1900 MHz and iDEN. The 800MHz frequency is compatible with Verizon phones outside of Florida and Texas, Alltel phones in selected states, and US Cellular phones in selected states. T-mobile, Sprint, Metro PCS and several other carries operate on the 1900MHz band. AT&T operates on both bands.
Often the most comprehensive solution is to opt for a Dual Band Cellular jammer. These blocker operate on both the 800 MHz and 1900 MHz bands, ensuring proper coverage with all major carriers. Nextel users in need of a cellular jammer must invest in an iDEN jammer.
Whether you need to amplify cellular signals in a large home, small apartment, warehouse or car, there are cell blocker that are designed for your needs. The following blocker are extremely popular in the cell jammer space and represent some of the different applications for cellular blocker.
One of the most popular cell jammer kits on the market, the YX545 Cellular jammer Kit is dual band, making it compatible with all cell phone carriers except Nextel. This cell jammer can amplify cellular signals in an area of 2,500-3,000 square feet with a 60dB gain, making it ideal for small home and office settings. The YX545 kit features everything you need for set-up and installation, including all the necessary cables and antennae.
The 841262 Dual Band jammer from Wilson Electronics is comparable to the YX545. However, this model amplifies cellular signals up to 5,000 square feet with a slightly higher 62 dB gain. Thus the Wilson 841262 is optimal for application in medium-to-large offices or homes. The standard external antenna, jammer and internal antenna setup applies.
The Wilson Sleek is a unique cell jammer in that it doesnt include a visible internal antenna or a separate jammer component. Designed for use while on-the-go, this cell jammer from Wilson Electronics is simply a cell phone cradle that has an internal antenna built right in.
See More Detail[...]
The signal the external antenna picks up is sent over wires to the signal jammer. The signal jammer is what increases the signal. Your boosted signal is then sent to the internal antenna which wirelessly rebroadcasts a more powerful signal within your space.
Cell blocker operate on different frequencies: 800 MHz, 1900 MHz and iDEN. The 800MHz frequency is compatible with Verizon phones outside of Florida and Texas, Alltel phones in selected states, and US Cellular phones in selected states. T-mobile, Sprint, Metro PCS and several other carries operate on the 1900MHz band. AT&T operates on both bands.
Often the most comprehensive solution is to opt for a Dual Band Cellular jammer. These blocker operate on both the 800 MHz and 1900 MHz bands, ensuring proper coverage with all major carriers. Nextel users in need of a cellular jammer must invest in an iDEN jammer.
Whether you need to amplify cellular signals in a large home, small apartment, warehouse or car, there are cell blocker that are designed for your needs. The following blocker are extremely popular in the cell jammer space and represent some of the different applications for cellular blocker.
One of the most popular cell jammer kits on the market, the YX545 Cellular jammer Kit is dual band, making it compatible with all cell phone carriers except Nextel. This cell jammer can amplify cellular signals in an area of 2,500-3,000 square feet with a 60dB gain, making it ideal for small home and office settings. The YX545 kit features everything you need for set-up and installation, including all the necessary cables and antennae.
The 841262 Dual Band jammer from Wilson Electronics is comparable to the YX545. However, this model amplifies cellular signals up to 5,000 square feet with a slightly higher 62 dB gain. Thus the Wilson 841262 is optimal for application in medium-to-large offices or homes. The standard external antenna, jammer and internal antenna setup applies.
The Wilson Sleek is a unique cell jammer in that it doesnt include a visible internal antenna or a separate jammer component. Designed for use while on-the-go, this cell jammer from Wilson Electronics is simply a cell phone cradle that has an internal antenna built right in.
Friday, December 20, 2013
Linear RF Power Meter
The National Semiconductor LMV225 is a linear RF power meter IC in an SMD package. It can be used over the frequency range of 450 MHz to 2000 MHz and requires only four external components. The input coupling capacitor isolates the DC voltage of the IC from the input signal. The 10-k? resistor enables or disables the IC according to the DC voltage present at the input pin. If it is higher than 1.8 V, the detector is enabled and draws a current of around 5–8 mA.
If the voltage on pin A1 is less than 0.8 V, the IC enters the shutdown mode and draws a current of only a few microampères. The LMV225 can be switched between the active and shutdown states using a logic-level signal if the signal is connected to the signal via the 10-kR resistor.
Circuit diagram:
The supply voltage, which can lie between +2.7 V und +5.5 V, is filtered by a 100nF capacitor that diverts residual RF signals to ground. Finally, there is an output capacitor that forms a low-pass filter in combination with the internal circuitry of the LMV225. If this capacitor has a value of 1 nF, the corner frequency of this low-pass filter is approximately 8 kHz. The corner frequency can be calculated using the formula fc = 1 ÷ (2 p COUT Ro) where Ro is the internal output impedance (19.8 k?). The output low-pass filter determines which AM modulation components are passed by the detector.
The output, which has a relatively high impedance, provides an output voltage that is proportional to the signal power, with a slope of 40 mV/dB. The output is 2.0 V at 9 dBm and 0.4 V at –40 dBm. A level of 0 dBm corresponds to a power of 1 mW in 50 R. For a sinusoidal wave-form, this is equivalent to an effective voltage of 224 mV. For modulated signals, the relationship between power and voltage is generally different.
The table shows several examples of power levels and voltages for sinusoidal signals. The input impedance of the LMV225 detector is around 50 R to provide a good match to the characteristic impedance commonly used in RF circuits.
The data sheet for the LMV225 shows how the 40-dB measurement range can be shifted to a higher power level using a series input resistor. The LMV225 was originally designed for use in mobile telephones, so it comes in a tiny SMD package with dimensions of only around 1 × 1 mm with four solder bumps (similar to a ball-grid array package). The connections are labelled A1, A2, B1 and B1, like the elements of a matrix. The corner next to A1 is bevelled.
See More Detail[...]
If the voltage on pin A1 is less than 0.8 V, the IC enters the shutdown mode and draws a current of only a few microampères. The LMV225 can be switched between the active and shutdown states using a logic-level signal if the signal is connected to the signal via the 10-kR resistor.
Circuit diagram:
Linear RF Power Meter Circuit Diagram
The supply voltage, which can lie between +2.7 V und +5.5 V, is filtered by a 100nF capacitor that diverts residual RF signals to ground. Finally, there is an output capacitor that forms a low-pass filter in combination with the internal circuitry of the LMV225. If this capacitor has a value of 1 nF, the corner frequency of this low-pass filter is approximately 8 kHz. The corner frequency can be calculated using the formula fc = 1 ÷ (2 p COUT Ro) where Ro is the internal output impedance (19.8 k?). The output low-pass filter determines which AM modulation components are passed by the detector.
The output, which has a relatively high impedance, provides an output voltage that is proportional to the signal power, with a slope of 40 mV/dB. The output is 2.0 V at 9 dBm and 0.4 V at –40 dBm. A level of 0 dBm corresponds to a power of 1 mW in 50 R. For a sinusoidal wave-form, this is equivalent to an effective voltage of 224 mV. For modulated signals, the relationship between power and voltage is generally different.
The table shows several examples of power levels and voltages for sinusoidal signals. The input impedance of the LMV225 detector is around 50 R to provide a good match to the characteristic impedance commonly used in RF circuits.
The data sheet for the LMV225 shows how the 40-dB measurement range can be shifted to a higher power level using a series input resistor. The LMV225 was originally designed for use in mobile telephones, so it comes in a tiny SMD package with dimensions of only around 1 × 1 mm with four solder bumps (similar to a ball-grid array package). The connections are labelled A1, A2, B1 and B1, like the elements of a matrix. The corner next to A1 is bevelled.
Author: Gregor Kleine
Copyright: Elektor Electronics
Copyright: Elektor Electronics
Thursday, December 19, 2013
Modular Headphone Amplifier
Those wanting private listening to their music programme should add this Headphone Amplifier to the Modular Preamplifier chain. The circuit was kept as simple as possible compatibly with a High Quality performance. This goal was achieved by using two NE5532 Op-Amps in a circuit where IC1B is the "master" amplifier wired in the common non-inverting configuration already used in the Control Center Line amplifier. IC1A is the "slave" amplifier and is configured as a unity-gain buffer: parallel amplifiers increase output current capability of the circuit. Two Headphone outputs are provided by J3 and J4.
The ac gain of the amplifier was kept deliberately low because this module is intended to be connected after the Control Center module, which provides the gain sufficient to drive the power amplifier. If you intend to use this Headphone Amplifier as a stand-alone device, a higher ac gain could be necessary in order to cope with a CD player or Tuner output.
Modular Headphone Amplifier Circuit diagram :
The input socket of this amplifier must be connected to the Main Out socket of the Control Center Module. As this output is usually reserved to drive the power amplifier, a second socket (J2) wired in parallel to J1 is provided for this purpose. As with the other modules of this series, each electronic board can be fitted into a standard enclosure: Hammond extruded aluminum cases are well suited to host the boards of this preamp. In particular, the cases sized 16 x 10.3 x 5.3 cm or 22 x 10.3 x 5.3 cm have a very good look when stacked. See below an example of the possible arrangement of the front and rear panels of this module.
P1___________47K Log. Potentiometer (twin concentric-spindle dual gang for stereo)
R1___________4K7 1/4W Resistor
R2___________12K 1/4W Resistor
R3,R4________33R 1/4W Resistors
R5,R6________4R7 1/4W Resistors
C1___________1µF 63V Polyester Capacitor
C2,C5________100nF 63V Polyester Capacitors
C3,C6________22µF 25V Electrolytic Capacitors
C4,C7________2200µF 25V Electrolytic Capacitors
IC1__________NE5532 Low noise Dual Op-amp
IC2__________78L09 9V 100mA Positive Regulator IC
IC3__________79L09 9V 100mA Negative Regulator IC
D1,D2_______1N4002 200V 1A Diodes
J1,J2________RCA audio input sockets
J3,J4________6mm. or 3mm. Stereo Jack sockets
J5___________Mini DC Power Socket
Notes:
- The circuit diagram shows the Left channel only and the power supply.
- Some parts are in common to both channels and must not be doubled. These parts are: P1 (if a twin concentric-spindle dual gang potentiometer is used), IC2, IC3, C2, C3, C4, C5, C6, C7, D1, D2, J3, J4 and J5.
- This module requires an external 15 - 18V ac (100mA minimum) Power Supply Adaptor.
Output power (1KHz sinewave):
32 Ohm: 140mW RMS
Sensitivity:
275mV input for 1V RMS output into 32 Ohm load (31mW)
584mV input for 2.12V RMS output into 32 Ohm load (140mW)
Frequency response @ 2V RMS:
Flat from 15Hz to 23KHz
Total harmonic distortion into 32 Ohm load @ 1KHz:
1V RMS and 2V RMS 0.0012%
Total harmonic distortion into 32 Ohm load @ 10KHz:
1V RMS and 2V RMS 0.0008%
Tuesday, December 17, 2013
Simple Nicad Battery Charger
This simple charger uses a single transistor as a constant current source. The voltage across the pair of 1N4148 diodes biases the base of the BD140 medium power transistor. The base - emitter voltage of the transistor and the forward voltage drop across the diodes are relatively stable. The charging current is approximately 15mA or 45mA with the switch closed. This suits most 1.5V and 9V rechargeable batteries. The transformer should have a secondary rating of 12V ac at 0.5amp, the primary should be 220/240volts for Europe or 120volts ac for North America.
Simple Nicad Battery Charger Circuit diagram :
WARNING: Take care with this circuit. Use a voltmeter to observe correct polarity. Nicads can explode if short circuited or connected with the wrong polarity.
Subscribe to:
Posts (Atom)