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  1. audioguru2

    what kind of amp do i need?

    The output of a microphone is a very low level, much lower than the level from a pc. An electret mic needs to be powered properly from a filtered supply through a series resistor. Therefore you need a preamp suitable for whichever mic you will use. If you use the pc amplified speaker to drive...
  2. audioguru2

    0-30V Stabilized Power Supply

    Sorry. I cannot follow the wiring of your stripboard circuit.
  3. audioguru2

    LED Audio Spectrum Analyzer HELP Needed!

    Multiplexing LEDs causes each LED to have current only for a moment. Then the average LED current is low which produces low brightness. For normal brightness then the peak LED current must be much higher but we do not know what is the maximum allowed peak current and duration for your LEDs.
  4. audioguru2

    0-30V Stabilized Power Supply

    The schematic shows that only U3 uses the -1.3V supply because its output must go a little negative due to the forward voltage drop of D9 when the output of the project is shorted. I cannot trace your stripboard layout since none of the parts in your photo are numbered.
  5. audioguru2

    Solar driven car

    The silly looking "car" cost $100,000.00 to make.
  6. audioguru2

    0-30V Stabilized Power Supply

    The 24VAC transformer might produce 25.5VAC with no load. Its peak voltage is (the root of 2) 1.414 times higher at +36V and the bridge rectifier with no load drops it to about +35V. OF COURSE you MUST connect the main filter capacitor! Your meter is WRONG to measure 74V! Then something is...
  7. audioguru2

    0-30V Stabilized Power Supply

    Hello big Zee, Two weeks ago you said you used a 24V transformer. The bridge rectifier charges your main filter capacitor to about +35V which is the positive supply voltage for U2. The maximum output voltage of U2 is about 1V less than its positive supply so it might go as high as +34V. U2 is...
  8. audioguru2

    Solar driven car

    You answered your own question. It seems to be impossible unless it is a lightweight little toy car.
  9. audioguru2

    Solar driven car

    There are many electric scooters creeping along roads today. There are also many electric wheelchairs. There are also a few VERY expensive electric cars.
  10. audioguru2

    Solar driven car

    A starter motor uses A LOT of power. It is not designed to run continuously, it is designed to start an engine in a couple of seconds.
  11. audioguru2

    0-30 Vdc Stabilized Power Supply

    The BZX79C5V6 zener diode that I recommend for D8 is 5.6V when its current is near 5mA. R4 also has 5.6V across it so its current and the zener's current are 5.6mA. RV1 is the trimpot to adjust the output offset voltage. It varies the output voltage plus and minus a small amount. When the...
  12. audioguru2

    Solar driven car

    Your "car" will probably need at least 4 times as much power to go slowly towards the wind or up a small hill. Some countries have extremely small little cars like this one:
  13. audioguru2

    Solar driven car

    At noon on a sunny day with the sun directly facing the solar panel your "car" (wheelchair?) will be creeping along with only about half of one horsepower. When it is morning or afternoon then the power will be less. Cloudy? Then It might not move.
  14. audioguru2

    0-30V Stabilized Power Supply

    The knob (or electronic pot) used to set the amount of current is CALIBRATED so that when it is set at maximum the current is exactly 3.0A, set at halfway the current is exactly 1.50A, etc. Usually the knob points at numbers on the dial surrounding it. The maximum current is simply calibrated...
  15. audioguru2

    0-30V Stabilized Power Supply

    U1 has its voltage gain set to 2 times by R5 and R6. So the 5.6V zener diode D8 has its voltage doubled to +11.2V at the output of U1. Check that D8 is a 5.6V low current (5mA) zener diode and check the values of R4, R5 and R6.
  16. audioguru2

    0-30V Stabilized Power Supply

    Look at my sketch of U2 Alone. Pin 3 of U2 has: 1) D9 but it is reversed biased so it does nothing. 2) R8 and R9 in series from the voltage setting pot. 3) Filter capacitor C4 to ground. There is nothing to cause pin 3 to be stuck at +1.14V so check your pcb to make sure there is nothing that...
  17. audioguru2

    Some reasonable censorship required

    I agree that the garbage circuit is horrible and cannot work.
  18. audioguru2

    0-30V Stabilized Power Supply

    Big Zee, Your camera is not clear enough for us to see any details. I think since you had wiring problems with the output transistors then that caused U2 to be destroyed. Replace it. Here is a sketch that shows how U2 should work. It has the driver and output transistors removed but the output...
  19. audioguru2

    0-30V Stabilized Power Supply

    Big Zee, Your pcb shows that all the pins on the BD139 driver transistor are shorted together. Guber, The 10V zener diode D1 has 7mA for the LED and 3.5mA for opamp U3 in it so its max current is 10.5mA and it dissipates 10V x 10.5mA= 105mW. A 0.5W or 1W zener diode will be fine. 1N758A...
  20. audioguru2

    0-30V Stabilized Power Supply

    Hello Big Zee, Your image of the pcb is too small to read any of the part numbers. I cannot see the pins of the driver transistor. The 2N3055 has a different and metal case than the transistors you are using. Are they TIP3055 by Motorola/Freescale? Without a load your 24VAC transformer probably...
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