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  1. audioguru2

    Flyback driver experiments

    Hi Virus, Steven or someone else posted pics of Huge sparks from a switch being opened on a high voltage distribution line (oops, they forgot to turn off the power first), then there was a nice video of an electrical substation blowing-up and its deadly oil burning all the way down the hill. ;D
  2. audioguru2

    0-30 Vdc Stabilized Power Supply

    I am sorry I missed your question before. In this thread we discuss problems with the original design for this project and fixes for them. The voltage and current of the original spec'd transformer were too small. Increasing the transformer's voltage means that special high voltage opamps must...
  3. audioguru2

    Mystery voltage on input pins of 7408N (AND)

    That's correct. Your circuit needs something on its inputs to pull down the TTL gates' inputs to about 0.4V with 1.6mA. Ohm's Law calculates each resistor to ground to be 250 ohms, but 270 ohms will be OK. Since your inputs are 5V, then each 270 ohm resistor will draw 18.5mA or a whopping 74mA...
  4. audioguru2

    Flyback driver experiments

    Hi Virus, You have a nice circuit but I think it makes wimpy little sparks only 2cm long. I think Steven's circuit makes big, fat, noisy lightning bolts about 1m or 2m long! Isn't that right, Steven? ;D ;D
  5. audioguru2

    Mystery voltage on input pins of 7408N (AND)

    The 7408 is an old fashioned (yours is more than 24 years old, I remember 1981) TTL logic IC. TTL means Transistor-Transistor-Logic. The input is the emitter of an NPN transistor that floats high if there isn't anything pulling it down to a low. Each input needs 1.6mA to pull it down to a low...
  6. audioguru2

    My first project

    Hi Cyril, I suggest using the pic's outputs to drive each LED directly, through 240 ohm current-limiting resistors. The LED current will be typically 10mA which would quickly kill little button cells. I suggest using a low-dropout regulator like an LM2931AZ-5.0 which still regulates with a...
  7. audioguru2

    designing a power audio amplifier with OP AMP

    Hi Shaiq, Good for you and your god! You built it well and it works well. ;D Can you turn up its gain high enough to get acoustical feedback howling? Does it have enough power to be loud enough? Does the LM380 get hot? What don't you understand about its circuit?
  8. audioguru2

    9v to 6v DC/DC Converter

    Yes from a power supply. A 6V battery drops to 4V during its life, which is too low. No, it isn't needed with a power supply. A tiny AC to DC adapter will probably cause mains hum. Try a 6V/500mA adapter that will have an output voltage of about 8V at the low current of the circuit, and will...
  9. audioguru2

    500W_inveter

    The old MM5369 hasn't been made since 1997. I got two but you can't have them. ;D Google MM5369 and you'll find people selling theirs and circuits to replace it.
  10. audioguru2

    digital elec-stetho..

    But you have only part of a filter since its R5 is missing. It will oscillate like that. If their values aren't the same then the filter will be messed-up with a droopy response or a peak and oscillation. If their values are less than 1k then opamps can't drive them. A Schmitt-trigger doesn't do...
  11. audioguru2

    My first project

    Thanks, Ed. Happy New Year to you too. ;D
  12. audioguru2

    My first project

    It isn't designed to pass current like for your LEDs. Its input and output must be referenced to its supply voltage (your LEDs and their batteries are floating) and if the batteries for the LEDs are still connected when its power is shut off it will latch. When passing power it works best with...
  13. audioguru2

    0-30 Vdc Stabilized Power Supply

    The meters are fine with a battery so they will probably also work fine with a completely separate power supply. I think Ante said he wound his own secondary winding on his project's transformer for a separate power supply for his meters.
  14. audioguru2

    designing a power audio amplifier with OP AMP

    Then the breadboard has intermittert contacts, doesn't it? The circuit won't work with a condenser mic. A condenser mic needs an external 48V power supply. This circuit needs an electret mic that has the high voltage built-in inside its special electret material. I don't know what you mean by...
  15. audioguru2

    designing a power audio amplifier with OP AMP

    Yes, connect together all the ground pins on the LM380. A breadboard can't pass the high current of an audio power amplifier. I've built many good ones on Veroboard. Your power supply's voltage shouldn't change much, it is too weak and might be causing the noise.
  16. audioguru2

    designing a power audio amplifier with OP AMP

    Hi Shaiq, Happy New Year! ;D It is too bad that your amplifier doesn't work yet. You are correct, the negative wire of your 12V to 15V power supply is the circuit's ground. Breadboards usually mess-up high gain circuits like this one. Maybe your noise is because you didn't use shielded cable...
  17. audioguru2

    Variable DC Power Supply

  18. audioguru2

    Help needed with metronome using 555

    I noticed that the polarity of C2 is backwards and it won't last very long. The output of the 555 is high most of the time. I agree with Edward that the 12V from the adapter is fluctuating with each beat. Using a 15VDC adapter with a 7812 regulator IC will fix it. ;D
  19. audioguru2

    0-30 Vdc Stabilized Power Supply

    Hi Rubick, Sure, try a 100nF cap across the input of your voltmeter IC. Also try a battery to power it if that doesn't work.
  20. audioguru2

    My first project

    I lost the 1967 licence plates from my very 1st car. My circuits shine on the ceiling then its reflection lights up everything. My "mood lights" project isn't posted anywhere. It uses a positive-feedback arrangement to make the voltage ramps reverse-exponential, so they look like their...
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