Showing posts with label high. Show all posts
Showing posts with label high. Show all posts
Wednesday, October 29, 2014
High Fidelity MOSFET Power Amplifier 150 W
This amplifier is designed to be as flexible as possible, with no bad habits. Indeed, it will operate stably with supply voltages as low as +/-5V (completely pointless, but interesting), all the way to the maximum supply voltage of +/-70V. The only change that is needed is to trim the MOSFET bias pot! With the full supply voltage of +/-70V (which must not be exceeded!), RMS power is around 180W into 8 ohms, or 250W into 4ohms. Short term (or "music") power is typically about 240W into 8 ohms and 380W into 4 ohms. Note that depends to a very great degree on the power supply, and a very robust supply is an absolute requirement for tThe maximum output. In general, unless you really need the maximum possible power, I suggest that you limit the supply voltage to ±56V using a 40+40V transformer. You will get around 150W into 8 ohms from this supply voltage (short-term), but you also relax the demands placed on the MOSFETs and heatsinks. It is worth noting that a MOSFET amp will always produce less power than a bipolar transistor version using the same supply voltage. Even using an auxiliary supply will make only a small difference (one reason I elected not to add the extra complexity). A bipolar design using a ±70V supply can be expected to produce something in the order of 270W into 8 ohms, and well over 500W into 4 ohms. The specified MOSFETs have a rated Vds (saturated voltage, Drain to Source) of 12V at full current, and that is simply subtracted from the DC value of the supply voltage. Using the same ±70V supply with a MOSFET amp will give less power than quoted above
Basic Performance Figures
Low Power Version
As shown in the schematics below (figures 1 and 2), the amplifier can be made in high or low power version, and although there is a bit of vacant PCB real estate in the low power design, it is significantly cheaper to make and will be more than sufficient for most constructors. If this version is built (using only 1 pair of MOSFETs), it is essential to limit the supply voltage to +/-56V so that it can drive both 4 and 8 ohm loads without excess dissipation. With this voltage, expect about 100W continuous into 8 ohms, and around 150W into 4 ohms. Naturally, dual MOSFET pairs may be used at this voltage as well, providing much better thermal performance (and therefore cooler operation), far greater peak current capability and slightly higher power. This version may be used at any voltage from +/-25V to +/-42V.
| Parameter | Measurement | Conditions |
| Output Power | > 180W | < 1% THD, 8Ω |
| > 275W | < 1% THD, 4Ω | |
| DC Offset | < 20mV | Typical |
| Noise | < 2mV RMS | Unweighted (-54dBV) |
| THD | 0.015% | No load, 30V RMS output, 1kHz |
| 0.017% | 8 Ohms, 30V RMS output, 1kHz | |
| 0.02% | 4 Ohms, 30V RMS output, 1kHz | |
| Output Impedance | < 10 mΩ | 1kHz, 4Ω load |
| < 25 mΩ | 10kHz, 4Ω load | |
| Frequency Response | 10Hz to 50kHz | At 1W, -1.5dB |
Low Power Version
As shown in the schematics below (figures 1 and 2), the amplifier can be made in high or low power version, and although there is a bit of vacant PCB real estate in the low power design, it is significantly cheaper to make and will be more than sufficient for most constructors. If this version is built (using only 1 pair of MOSFETs), it is essential to limit the supply voltage to +/-56V so that it can drive both 4 and 8 ohm loads without excess dissipation. With this voltage, expect about 100W continuous into 8 ohms, and around 150W into 4 ohms. Naturally, dual MOSFET pairs may be used at this voltage as well, providing much better thermal performance (and therefore cooler operation), far greater peak current capability and slightly higher power. This version may be used at any voltage from +/-25V to +/-42V.
The same PCB is used, but has an extra pair of MOSFETs. Since the devices are running in parallel, source resistors are used to force current sharing. Although these may be replaced by wire links, I do not recommend this. This version may be operated at a maximum supply voltage of +/-70V, and will give up to 180W RMS into 8 ohms, and 250W into 4 ohms. Short term (peak) power is around 240W into 8 ohms and 380W into 4 ohms. These figures are very much dependent on your power supply regulation, determined by the VA rating of the transformer, size of filter caps, etc.
Figure 2 - High Power Version
Although not shown, the transistors and MOSFETs are the same in this version as for the low power variant. The additional capacitors (C11 and C12) shown are to balance the gate capacitance. The P-Channel MOSFETs have significantly higher gate capacitance than their N-Channel counterparts, and the caps ensure that the two sides of the amp are roughly equal. Without these caps, the amp will almost always be unstable.
As noted above, the PCB is the same for both versions, but for Fig. 2 it is fully populated with 2 pairs of power MOSFETs. The high power version may also be used at lower supply voltages, with a slight increase in power, but considerably lower operating temperatures even at maximum output, and potentially greater reliability.
With both versions, the constructors page gives additional information, and the schematics there include an enhanced Zobel network at the output for greater stability even with the most difficult load. This is provided for on the PCB, and allows the amp to remain stable under almost any conditions.
The entire circuit has been optimised for minimum current in the Class-A driver, while still providing sufficient drive to ensure full power capability up to 25kHz. The slew rate is double that required for full power at 20kHz, at 15V/us, and while it is quite easy to increase it further, this amp already outperforms a great many other amps in this respect, and faster operation is neither required nor desirable.
Note - There are actually two caps marked C5, and two marked C6. This is what is on the PCB overlay, and naturally was not found until it was too late. Since these caps cannot be mixed up, it will not cause a problem.
In both versions of the amp, R7 and R8 are selected to provide 5mA current through the voltage amplifier stage. You will need to change the value to use a different supply voltage ...
R7 = R8 = Vs / 10 (k) (Where Vs is one supply voltage only)
For example, to set the correct current for ±42V supplies ...
R7 = R8 = 42 / 10 = 4.2k (use the next lower standard value - 3.9k)
Construction
The suggested power supply is completely conventional. Although a small amount of additional power can be obtained by using an auxiliary supply (to boost the rail voltage for the MOSFET drive stage), this is at the expense of greater complexity and more things to go wrong. The transformer for the supply should be matched to the expected power you wish to obtain from the amp. The following table shows the recommended transformer voltage and VA rating for a single channel - either use two transformers or a single unit with twice the VA rating shown for stereo.
AC Volts DC Volts VA Power (8Ω)
20-0-20 +/-28V 100 40
25-0-25 +/-35V 100 50
30-0-30 +/-42 160 80
40-0-40 +/-56V 200 150 (Recommended Supply Voltage)
50-0-50 +/-70V 300 240
Note that all powers shown are "short term" or peak - continuous power will always be less as the supply collapses under load. Peak power levels are usually achieved (or approached) with most music because its transients are generally between 6dB and 10dB greater than the average power output. Transformer VA ratings shown are a guide only - larger or smaller units may be used, with a marginal increase or reduction of peak power. Always use at least the size shown for subwoofer use! Values in bold are preferred, and will give enough power for most systems along with optimum reliability and low operating temperature.
Figure 3 shows the power supply circuit diagram for a ±56V supply, and there is nothing new about it. As I always recommend, the bridge rectifier should be a 400V/35A chassis mount type, and should be properly chassis mounted using heatsink compound.
Filter capacitors must be rated to at least the nominal supply voltage, and preferably higher. If possible, use 105°C rated caps, and join the earthed terminals very solidly to form the star earthing point.
Note - The fuse should be selected according to the size of the power transformer. For any toroidal transformer over 300VA, a soft start circuit is highly recommended. Use the transformer manufacturers suggested fuse - if this information is not available, ask the supplier - not me!
The DC supply must be taken from the capacitor terminals - never from the bridge rectifier. Using several small capacitors will give better performance than a single large one, and is usually cheaper as well. For example, the performance of 10 x 1,000uF capacitors is a great deal better (in all respects) than a single 10,000uF cap, at between 50% to 70% of the cost of the large unit. This lunch is not free, but it is heavily discounted
Monday, September 15, 2014
High Voltage regulator schematics
Friday, September 12, 2014
Build a 12v to 5v DC high efficiency SMPS buck converter using 34063 IC
This project converts 12v DC to a regulated 5v DC at up to 1.8 amps, suitable for driving a tablet computer from a 12v car battery in a power blackout etc.
The schema for this buck converter is nothing original, basically it is the schema from the 34063 IC datasheet, and all I did was to use an external PFET instead of the external PNP transistor shown in the datasheet. The external PFET allows currents up to a few amps at good efficiency, however I have used hard current limiting at 1.8A for safety and good performance in this prototype.
Energy conversion efficiency is very high due mainly to the choice of external components used with the cheap 34063 SMPS IC.
The schema for this buck converter is nothing original, basically it is the schema from the 34063 IC datasheet, and all I did was to use an external PFET instead of the external PNP transistor shown in the datasheet. The external PFET allows currents up to a few amps at good efficiency, however I have used hard current limiting at 1.8A for safety and good performance in this prototype.
Energy conversion efficiency is very high due mainly to the choice of external components used with the cheap 34063 SMPS IC.
PCB layout.
The prototype was tested in hardware, please excuse the messiness. The layout is far from ideal, I did it this way to allow easy swapping of parts and just to be lazy, to save the effort of making a PCB. However it still works pretty good, and a proper PCB would improve performance a little bit.
PFET choice.
I did not have a lot of PFETs in my parts box so I used a 100v 8A rated part. This was an SMD PFET so I just tacked it on the bottom of the PCB. It is efficient enough to not need a heatsink even at 5v 1.5A continuous output. The PFET I used was not ideal, its "Rds on" value is about 0.3v at 1.5A (0.2 ohms) which is too high and costs efficiency. Going to a 50v >20A PFET with an RDS <0.1 ohms or <0.05 ohms would give a noticable increase in efficiency.
Schottky diode choice.
I used a TO-220 60v dual 10A schottky diode pack (total 20A). This is a no-brainer, although this is overkill these diodes are only $1-$2 and can also be pulled for free from any old PC PSU and most commercial SMPS supplies. Besides the safety of being very large and over-rated, the main benefit is these diodes have a very low forward voltage drop of <0.3v at 1.5A or 2A and this equates to reduced losses (more efficiency).
Inductor choice.
This is just a commercial "3 amp" 24mm total diameter inductor/choke available from hobby suppliers like Altronics Australia. I think it is a 220uH or 330uH value, but sorry I lost the paperwork. A few other powdered-iron toroid inductors were tried and it is not that critical. It has 51 turns of 1.0mm diameter wire if that helps. The inductor measured 0.32mV at exactly 1A DC, so DC resitance was measured at 32 milliohms.
The prototype was tested in hardware, please excuse the messiness. The layout is far from ideal, I did it this way to allow easy swapping of parts and just to be lazy, to save the effort of making a PCB. However it still works pretty good, and a proper PCB would improve performance a little bit.
PFET choice.
I did not have a lot of PFETs in my parts box so I used a 100v 8A rated part. This was an SMD PFET so I just tacked it on the bottom of the PCB. It is efficient enough to not need a heatsink even at 5v 1.5A continuous output. The PFET I used was not ideal, its "Rds on" value is about 0.3v at 1.5A (0.2 ohms) which is too high and costs efficiency. Going to a 50v >20A PFET with an RDS <0.1 ohms or <0.05 ohms would give a noticable increase in efficiency.
Schottky diode choice.
I used a TO-220 60v dual 10A schottky diode pack (total 20A). This is a no-brainer, although this is overkill these diodes are only $1-$2 and can also be pulled for free from any old PC PSU and most commercial SMPS supplies. Besides the safety of being very large and over-rated, the main benefit is these diodes have a very low forward voltage drop of <0.3v at 1.5A or 2A and this equates to reduced losses (more efficiency).
Inductor choice.
This is just a commercial "3 amp" 24mm total diameter inductor/choke available from hobby suppliers like Altronics Australia. I think it is a 220uH or 330uH value, but sorry I lost the paperwork. A few other powdered-iron toroid inductors were tried and it is not that critical. It has 51 turns of 1.0mm diameter wire if that helps. The inductor measured 0.32mV at exactly 1A DC, so DC resitance was measured at 32 milliohms.
Schematic and operation.
Sorry for the hand-drawn schematic!
As you can see the schema is minimum parts. It uses just two resitors to drive the PFET from the IC (same as the datasheet), this is not ideal but was done to test the concept and see if a PFET can be driven as easily as the PNP transistor normally is. PFET turnon is good at 0.07uS, but turnoff is not great taking 0.8uS. This costs about 1-2% efficiency. The 560 ohm resistor could be reduced to speed up the turnoff, but this would increase losses in that resistor so it is a tradeoff.
34063 SMPS IC.
The 34063 IC does all the clever stuff, mainly it regulates voltage at 1.25v on VFB pin5. Because of the 6k8:2k2 voltage divider on the output, this gives very close to 5v, I actually saw about 5.01v-4.99v Vout in testing, very nice.
Max current limit resistor.
The resistor between Vin and pin7 sets the max inductor current limiting, this was set by me to roughly 0.18 ohms to give 1.8A current limiting. (Imax = 0.32v / R = 0.32v/0.18 = 1.78A). The current limit is best at slightly above the max required current. This gives better safety and also helps stabilise oscillation.
Caps etc.
CT used the datasheet value of 1nF. That gave oscillator value of 26.2kHz measured on pin3 (with no load), however the whole schema usually operated at 29-33kHz because of the way the regulation works in the IC. The filter caps; 680uF on the input and 1000uF on the output were chosen to be "good enough". Output ripple was approx 25-30mV which is fine.
Measured efficiency!
Sorry for the hand-drawn schematic!
As you can see the schema is minimum parts. It uses just two resitors to drive the PFET from the IC (same as the datasheet), this is not ideal but was done to test the concept and see if a PFET can be driven as easily as the PNP transistor normally is. PFET turnon is good at 0.07uS, but turnoff is not great taking 0.8uS. This costs about 1-2% efficiency. The 560 ohm resistor could be reduced to speed up the turnoff, but this would increase losses in that resistor so it is a tradeoff. 34063 SMPS IC.
The 34063 IC does all the clever stuff, mainly it regulates voltage at 1.25v on VFB pin5. Because of the 6k8:2k2 voltage divider on the output, this gives very close to 5v, I actually saw about 5.01v-4.99v Vout in testing, very nice.
Max current limit resistor.
The resistor between Vin and pin7 sets the max inductor current limiting, this was set by me to roughly 0.18 ohms to give 1.8A current limiting. (Imax = 0.32v / R = 0.32v/0.18 = 1.78A). The current limit is best at slightly above the max required current. This gives better safety and also helps stabilise oscillation.
Caps etc.
CT used the datasheet value of 1nF. That gave oscillator value of 26.2kHz measured on pin3 (with no load), however the whole schema usually operated at 29-33kHz because of the way the regulation works in the IC. The filter caps; 680uF on the input and 1000uF on the output were chosen to be "good enough". Output ripple was approx 25-30mV which is fine.
Measured efficiency!
Vin Iin Pin Vout Iout Pout Eff %
12.5v 670mA 8.375W 4.99 1.53A 7.63W 91.1%
12.5v 430mA 5.375W 5.00 1.00A 5.00W 93.0%
12.5v 210mA 2.625W 5.00 0.50A 2.50W 95.2%
Note! Readings were taken from meters with only 2 decimal point resolution and were not lab grade accuracy, so there may be a couple of percent error in readings.
Calculating efficiency (at 1.5A output).
The static power losses were seen on the scope and can be calculated;
PFET Rds on period loss = 0.3v / 12.5v = 2.4% loss
DIODE Vf off period loss = 0.28v * 1.53A * 0.56 offduty = 240mW = 2.8% loss
Inductor resistance loss = 1.53A squared * 0.032 ohms = 75mW = 0.9% loss
560 ohm resistor loss = 10.5v squared / 560 * 44% onduty = 87mW = 1.0% loss
Total static losses at 1.53A output = 7.1%
Calculated other (switching) losses = 100% - 91.1% - 7.1% = 1.8%
Scope current L1 inductor (on period) at 5v 1.5 amps.
Above is the on period current through the PFET and L1 inductor. As it is a PFET this is inverted so the pointy bit at the bottom is the max current, the top is zero current. At 1.5A and 32kHz the SMPS is very stable, as switching period is reduced becuase the peaks just hit the 0.32v max current limit set by my choice of 0.18 ohm resistor. (However voltage regulation is still the main regulation).
Duty cycle is about 44%, and current ripple in the inductor is nice and low with inductor current averaging 1.5A (ripple of 0.56A, between 1.22A and 1.78A). The noise spikes I suspect are from from my messy PCB with power and load wires everywhere and scope leads laying around next to the PCB and wiring.
Calculating efficiency (at 1.5A output).
The static power losses were seen on the scope and can be calculated;
PFET Rds on period loss = 0.3v / 12.5v = 2.4% loss
DIODE Vf off period loss = 0.28v * 1.53A * 0.56 offduty = 240mW = 2.8% loss
Inductor resistance loss = 1.53A squared * 0.032 ohms = 75mW = 0.9% loss
560 ohm resistor loss = 10.5v squared / 560 * 44% onduty = 87mW = 1.0% loss
Total static losses at 1.53A output = 7.1%
Calculated other (switching) losses = 100% - 91.1% - 7.1% = 1.8%
Scope current L1 inductor (on period) at 5v 1.5 amps.
Above is the on period current through the PFET and L1 inductor. As it is a PFET this is inverted so the pointy bit at the bottom is the max current, the top is zero current. At 1.5A and 32kHz the SMPS is very stable, as switching period is reduced becuase the peaks just hit the 0.32v max current limit set by my choice of 0.18 ohm resistor. (However voltage regulation is still the main regulation).
Duty cycle is about 44%, and current ripple in the inductor is nice and low with inductor current averaging 1.5A (ripple of 0.56A, between 1.22A and 1.78A). The noise spikes I suspect are from from my messy PCB with power and load wires everywhere and scope leads laying around next to the PCB and wiring.
Scope current L1 inductor at 5v 1.0 amps.
Same thing but at 1A. Frequency dropped a bit, closer to the 34063 oscillator freq of 26.2kHz, but still (just) triggering on the max current peaks. Current ripple now larger from approx 0.5A to 1.6A (average output 1A). Timing is still 20uS/hdiv but says 40uS on the Lcd as I had zoomed my h-axis (sorry).
Scope current L1 inductor at 5v 0.5 amps.
Here the L1 current has gone "discontinuous" meaning the L1 current is reduced to zero during the end of the off period, and has to start from 0 amps again during every on period. Typical of the regulation system used in a 34063 IC, the timing will "stutter" as needed to maintain Vout regulation at a steady 5.0v. This does not matter and the 34063 can be quite energy efficiency when "stuttering" in discontinuous mode like this. At less than 0.5 amps the stuttering can become very erratic looking, but this is all normal.
PFET drain/source voltage (main switching waveform).
(The PFET on period is the top of the waveform). Above you can see the PFET turnon (through a 10 ohm resistor) is nice and fast, It was about 0.07uS turnon time. However the turnoff is poor, because the turnoff is from a 560 ohm resistor and is slow at 0.8uS. This costs significant efficiency.
Using an external digital driver (like a 12v CMOS digital buffer/inverter chip?) to drive the PFET would improve turnoff time a lot and increase efficiency, but this was a test of using the simple datasheet example schema with an external PFET (instead of the suggested external PNP) and as proof of concept it still works well enough.
5v DC output showing voltage ripple.
Because it is a switching regulator there will always be some ripple on the DC output voltage. This is shown when running at 5v 1.5A and the ripple is typical and acceptable enough at 30-35mV.
Improving efficiency.
This schema was thrown together very quickly to show how to use a cheap common 34063 IC to get a high efficiency supply from 12v->5v DC at 0-1.5A or so. If you want to invest some effort it can be improved further;
1. My PFET is not a good choice, using a better PFET will give an easy 1% more efficiency, and would be the first choice.
2. The inductor is just an ordinary "off the shelf" type. A properly selected inductor or a good core hand wound for best performance could allow lower operating frequency and less current ripple, and maybe less DC ohms, and maybe pick up another 0.5% efficiency or so. (For lower operating freq CT should also be increased to 1.2nF or 1.5nF etc).
3. The PFET turnoff is too slow. Adding a cheap digital buffer IC could pick up 0.8-1.2% efficiency there from reduced switching losses and reduced loss from the 560 ohm resistor.
4. My PCB has very thin long tracks. Using a well designed PCB with thick short tracks for the main current paths might save 30 milliohms and give maybe 0.5% or more efficiency.
Bill of materials.
* 34063 SMPS 8pin IC (Fairchild/ON Semi/AIS etc, ie MC34063A or NCV34063A).
* 8pin IC socket (optional).
* PFET, rated more than double the input voltage and a few times the desired output current, preferably well under 0.1 ohm Rds on.
* Inductor L1 is a powdered iron toroid of 20-30 mm diameter, with thick wire >1.0mm preferred, 3A rated for a 1.5A capable supply. Value in the 150-470uH range, you may need to try a couple of different types. Ideally current ripple will be <50% at full output current.
* Schottky TO-220 dual 10A or dual 16A diode pack. Choose for low forward voltage, most brands are very good, parts can be found in any old PC PSU.
* 470-1000uF 35v electro cap.
* 1000uF 16-25v electro cap (25v will be larger and generally have a longer life).
* CT 1nF 25-50v ceramic or greencap.
* some 1/4W resistors; 560 ohm, 10 ohm, 6k8, 2k2.
* If you need a test load then a large 10W 4.7 ohm resistor will do.
Modifying the schema for 12v car operation.
This schema was designed for a car battery, generally 13.8v to 12.0v when running. If used in a car the schema needs more protection as the Vin might be >15v at times. I would use a 100 ohm resistor instead of the 10 ohm resistor. Also a 13v zener diode across the 560 ohm resistor will add safety for the PFET. A 12v line filter might also be advised, they can be bought from auto stores.
Modifying the schema for 24v operation.
Use 560 ohms instead of 10 ohms, so it now has two 560 ohm resistors. And again a 13v zener from PFET gate to source pin. With a 24v Vin you should use a higher inductor value and larger inductor core, 470uH and up are recommended.
[b]Modifying the schema for high output currents.[b]
The schema is meant for 5v out, 0-1.8A. It will do ok up to 2.5A just by changing the current limit resistor (at 2.5A the resitor should be 0.12 ohms or so).
Currents up to 5 amps or more should be ok, but use a larger inductor core size rated for more than the max amps you need, and again a larger inductor value helps >470uH is good. The diode pack will be fine, but the PFET should be rated for a few times more current than your max current. If needing 5A output I would use a 40-50v 60A TO-220 PFET which are a common size.
Changing output voltage.
Just change the 6k8 resistor, to change the output voltage to something other than 5.0v. Like most SMPS diagram it works best with roughly 2:1 Vin:Vout ratio, if using different ratios then again increasing the inductor value >470uH will help.
Source: http://forum.allaboutdiagram.com/showthread.php?t=7885
Sunday, September 7, 2014
Clean High gain Differential Instrumentation Amplifier
This schema includes input guarding, cable bootstrapping, and bias current compensation .
Differential bandwidth is reduced by Cl which also makes common-mode rejection less dependent on matching of input amplifiers
Differential bandwidth is reduced by Cl which also makes common-mode rejection less dependent on matching of input amplifiers
High gain Differential Instrumentation Amplifier
Build a High Voltage Dc Generator Wiring diagram Schematic
High Voltage Dc Generator Circuit Diagram. In the miniature high-voltage dc generator, the input to the schema, taken from a 12-Vdc power supply, is magnified to provide a 10,000-Vdc output causing a pulsating signal, of opposite polarity, to be induced in Tl`s secondary winding.
The pulsating dc output at the secondary winding of Tl (ranging from 800 to 1000 V) is applied to a 10-stage voltage-multiplier schema, which consists of D1 through D10, and C3 through C12. The multiplier schema increased the voltage 10 times, producing an output of up to 10,000 Vdc. The multiplier accomplishes its task by charging the capacitors (C3 tlirough C12); the output is a series addition of the voltages on all the capacitors in the multiplier. In order for the schema to operate efficiently, the frequency of the square wave, and therefore the signal applied to the multiplier, must be considered.
The output frequency of the oscillator (Ul-a) is set by the combined values of Kv Rr>, and C{ (which with the values specified is approximately 15 kHz). Potentiometer R5 is used to fine tune the output frequency of the oscillator. The higher the frequency of the oscillator, the lower the capacitivc reactance in the multiplier. Light-emitting diode LED1 serves as an input-power indicator, and neon lamp NE1 indicates an output at the secondary of Tl. A good way to get the maximum output at the multiplier is to connect an oscilloscope to the high-voltage output of the multiplier, via a high-voltage probe, and adjust potentiometer R5 for the maximum voltage output.
High Voltage Dc Generator Circuit Diagram
Thursday, September 4, 2014
High Voltage Generator Wiring diagram Schematic
This is a short High Voltage Generator Circuit Diagram of a high voltage generator and can be mounted in a small space and powered by rechargeable or simple batteries, the schema generates a voltage low current but a high turn-on of about 200 to 400 V harmless to humans, of course, but is able to give a pretty nasty shock.
High Voltage Generator Circuit Diagram
Here is a project that could be useful this summer on the beach, to prevent anyone touching your things left on your beach towel while you was swimming, you can equally well use it in the office or workshop when you return to work. It operates as a low frequency oscillator, which makes it possible to convert the battery voltage into a DC voltage alternating current that can be enhanced through the transformer.
Using a transformer with center tap as herein makes possible the construction of a Hartley oscillator transistor T1 around The output voltage can be used directly through R2 and R3 current limiting resistors, which should not in any circumstances be omitted or modified, they are what make the schema have security. You will then get about 200 V peak-to-peak, which is already quite unpleasant to the touch.
But you can also use a voltage doubler, shown at the bottom right of the figure, which will produce about 300 V, even more unpleasant to the touch. Here too, of course, the resistance, you know how R4 and R5, should always be present. It can be used in small electric fences, chase away animals, etc.
Sunday, August 31, 2014
Simple 5V Supply High Side Switcher Wiring diagram Schematic
This is a Simple 5V Supply High-Side Switcher Circuit Diagram. This schema requiring only 10uA of quiescent current, the schema of (Fig. 62-1 (a)) produces only 0.1ohm ON-rises-trance. IC1 is a charge pump voltage converter to produce a 5V level, so analog switch IC2 can provide a 10-V swing to MOSFET Ql.
5V Supply High-Side Switcher Circuit Diagram
This schema uses a voltage converter to enable the analog switch to apply a 4.3V swing to logic level NMOS power transistor Q1. ON resistance is 0.03ohm typical. This schema uses additional stages in the voltage-multiplying schema to provide a higher gate voltage swing. This would enable the use of a converter for an NMOS switching transistor.
Monday, August 25, 2014
High Quality Intercom circuit
This is an intercom schema which use LM380 as the audio amplifier and 2 transistors as the microphone pre amplifier. The sound quality will be good enough with low cost building.
This schema consists of two identical intercom units. Each unit contains a power supply, microphone preamplifier, audio amplifier and a Push To Talk (PTT) relay schema. Only 2 wires are required to connect the units together. Due to the low output impedance of the mic preamp, screened cable is not necessary and ordinary 2 core speaker cable, or bell wire may be used.
Detail explanation about this intercom schema include the PCB layout, please visit this page
Read More..
This schema consists of two identical intercom units. Each unit contains a power supply, microphone preamplifier, audio amplifier and a Push To Talk (PTT) relay schema. Only 2 wires are required to connect the units together. Due to the low output impedance of the mic preamp, screened cable is not necessary and ordinary 2 core speaker cable, or bell wire may be used.
Detail explanation about this intercom schema include the PCB layout, please visit this page
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