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  1. audioguru2

    Digital Remote Thermometer

    Hi Buleye, Maybe you'll be the first person to build this simple project. Make it and let us know how well it works. ;D
  2. audioguru2

    Coil gun charger circuit

    Hi Steven, Why did you parallel three protection diodes? The 1000 volt 1N5408 has a peak current rating of a whopping 200A! I doubt that the flyback current exceeds 20A and is a very short duration so surely a single diode is fine. ;D Please post the schematic again since it got lost in the forum.
  3. audioguru2

    How does OptoIsolator Compensate circuit Work?

    A similar circuit with frequency compensation is shown in TI's datasheet.
  4. audioguru2

    555 timing circuit

    Alun's transistor is all you need. What's it for? To wake sleeping drivers? ???
  5. audioguru2

    Capacitor Size Matter?

    Hi Prateek, Large value capacitors are usually used as filters following a full-wave rectifier in high current equipment. Surges are infrequent but ripple current occurs continuousy, on every half-cycle of the mains. Because the load current is high, the capacitor's ripple current is also high...
  6. audioguru2

    Inverter Circuit 12V DC to 230VAC Sine Wave

    Hi Sasi, Your sine-wave inverters ar linear heaters. It is time to make them efficient with variable PWM. ;D
  7. audioguru2

    dc electronic load

    Hi Rhynato, Welcome to our forum. ;D The circuit design and cost depends entirely on how big the monster load will be. You could use "millions" of Mosfets in parallel operating as a variable resistor. You could use a few (maybe only 10) Mosfets switching-in a heater as a load at a high frequency...
  8. audioguru2

    Query about grounding in my project abt amplifier and which IC instead of LM383

    Hi Achin, Welcome to our forum. ;D The LM383 is old and was discontinued by its inventer, National Semi long ago. They don't have a sim file for it and I doubt that you'll find one. Select a newer amp IC. Are you asking about connecting the ground connection of your amp and its power supply to...
  9. audioguru2

    Convert 0-30V 3A PSU to 5A or more

    They are part of the half-wave rectified negative supply. C2 charges through D5 when the tranformer connection #2 swings positive. R2 limits its charging current so a small capacitor and diode can be used. C2 discharges through R2, D6, R3 and D7 to make the regulated -5.6V negative supply for...
  10. audioguru2

    How does OptoIsolator Compensate circuit Work?

    I haven't seen your other post yet. If the circuit uses an opto-isolator to sense and feedback the output current, then the circuit will also need a 2nd opto to automatically adjust it when the emitter gets dim with age or temperature.
  11. audioguru2

    Inverter Circuit 12V DC to 230VAC Sine Wave

    The only pure sine-wave inverter circuit posted so far is the one with a sine-wave function generator IC feeding some linear Mosfets that drive the step-up transformer. It is extremely inefficient. All the rest are square-wave with an efficiency of about 85% to 90% at full output.
  12. audioguru2

    NiCd Battery Powered LED Lamp

    Stepping up the voltage increases the battery current due to the Law of Energy. The two-cell Ni-Cad battery will be 2.5V over most of its life. If the LEDs need 8mA at 3V then they consume a power of 24mW, plus power for the step-up circuit. 24mW from the 2.5V battery will cause its current to...
  13. audioguru2

    power supply high pitch hum

    Hi Murrmax, About the only way to test a regulator is to power it and measure proper DC voltages on its input and output. You could also measure for any AC voltage on its input if its DC is low. Without a load on the regulator, its input AC should be nearly zero volts. So you have a headphones...
  14. audioguru2

    power supply high pitch hum

    Hi Murrmax, Welcome to our forum. ;D Please post the schematic of the power supply so we can see what it is. Maybe it is overloaded by a blown-up audio power amplifier as its load. Try measuring its voltage output without a load, then test it using resistors as a load. Maybe it can't supply the...
  15. audioguru2

    How does OptoIsolator Compensate circuit Work?

    They provide frequency compensation for the TL431 so it doesn't oscillate at a high frequency. A 2nd emitter also gets dim and with its detector in the negative feedback loop of the emitter or detector of the 1st emitter/detector then it causes automatic adjustment.
  16. audioguru2

    Convert 0-30V 3A PSU to 5A or more

    Hi BigPoppa, I mentioned the zeners and R4 that feeds one, but someone said that R2 gets very hot. Here is the latest parts list:
  17. audioguru2

    Convert 0-30V 3A PSU to 5A or more

    Hi BigPoppa, Welcome to our forum. ;D This thread is about modifying the original 0-30V/3A project to 5A. Your little transformer won't power this supply to 30V nor to 5A. The project's voltage control's range should be changed to match your transformer since it will allow only about 27V but the...
  18. audioguru2

    555 timing circuit

    Don't reset it with its reset pin #4 or the alarm will sound. Like I said before, "Use an NPN transistor to externally discharge its timing capacitor when the motion detector detects motion". Then it re-starts the timing without the alarm. Trigger pin #2 needs activation only at the beginning...
  19. audioguru2

    How does OptoIsolator Compensate circuit Work?

    Hi Guys, Optoisolators change the amount of signal passed with temperature change and the LED gets a little dimmer with age. A 2nd optoisolator can be used as a reference for the amount of signal passed and used inside another error amp. ;D
  20. audioguru2

    LM317 works Bad "SOS"

    I didn't know the camcorder has a light. It might draw 2A which overloads the LM317. Measure the output voltage of the LM317 when it is powering the camcorder with the light turned on. If the voltage drops then the LM317 is overloaded.
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