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  1. audioguru2

    help, help, help, it's too hot

    Hi Kevin, You are correct to choose a non-inverting opamp circuit, since the ADC0808 only has a positive input. Most opamps have built-in compensation, so we don't have to add any. Why did you choose such a high supply voltage? Your +,- 18V is the absolute maximum voltage for most opamps and...
  2. audioguru2

    help, help, help, it's too hot

    Hi Kevin, You seem to be mixing parts of an inverting opamp with a non-inverting opamp. I think that it should look like this:
  3. audioguru2

    how to calculate??

    Yeah, I agree Ante, Roy was a cool dude. May he rest in peace. I think he stole that song from Frank Sinatra.
  4. audioguru2

    What Chip Converts Decimal to Pulse ..?

    Hi Mhz, Good idea! Why don't you use a telephone dialer IC? Motorola and Philips used to make them. It will do exactly what you need, and probably can be speeded-up, but not as fast as Kevin's.
  5. audioguru2

    hv polarity indicator/ voltage optimizer

    Yeah, a neon bulb even lights with static electricity. Try attaching 1 wire of a neon bulb to a metal rod. The other wire to a small antenna. At night, ground the rod near a radio or TV station antenna, or under power lines. I think that the bulb will light pretty well. Then try it with a long...
  6. audioguru2

    Another INVERTER we can talk about..

    Who is counting?
  7. audioguru2

    Led display Digital Voltmeter question

    Hi Gonz, The "fixes" discussion that was posted a couple of days ago says to use 100K for R1.
  8. audioguru2

    voltage controlled oscillators

    Hi MP, Thanks for the good demo of a 74LS124 that is used as part of a phase-locked-loop, whose VCO follows the exact frequency and phase of a variable clock oscillator. But the VCO's frequency can simply be set with a DC voltage from a pot, then the clock oscillator and other parts aren't...
  9. audioguru2

    What Chip Converts Decimal to Pulse ..?

    Wait a minute, Mhz, Kevin's counter doesn't output the number of pulses that you want, and neither does his multiplexer. A counter can be preset by a binary input to a certain number that it starts counting from. Then its outputs count up or down from there. You could preset it to "5" from the...
  10. audioguru2

    voltage controlled oscillators

    A frequency-synthesiser's VCO jumps abruptly only to pre-determined frequencies, a VCO with a variable DC control voltage smoothly glides to any frequency (within its range).
  11. audioguru2

    What Chip Converts Decimal to Pulse ..?

    Sorry, Kevin. You are absolutely correct. Your clock frequency is "only" 1GHz, with your counter incrementing every 1ns.
  12. audioguru2

    What Chip Converts Decimal to Pulse ..?

    Hi Kevin, A whole ns? Then your counter will be running at 2GHz. Isn't that frequency a bit high for a simple keyboard multiplexer?
  13. audioguru2

    voltage controlled oscillators

    Kevin, A phase detector produces a DC correction voltage to adjust the frequency and phase of the VCO so that it is exactly the same as the crystal oscillator. You could put a switch-selected digital divider between the VCO and phase detector so that the VCO is an exact multiple of the crystal...
  14. audioguru2

    ITT Microphone Adapter

    Hi Yev, Seven pins is a lot for a microphone that needs only 2 or 3. Maybe it is a stereo mic, so it has 2 mics in 1 housing. Does it have a press-to-talk switch? An ohm-meter would tell you which pins are the switch contacts. Maybe it has a built-in camera, recorder and/or alcohol (or bad...
  15. audioguru2

    how to calculate??

    Hi Ray Orbison wannabe or fan, If you want the rise-time of the voltage across C3 to be the same, then you simply multiply the value of R1 by the ratio of supply voltages, which is 12 divided by 4.5, so it will be about 12.5K to 12.7K. If the circuit is activated by the junction of R3 and R5...
  16. audioguru2

    voltage controlled oscillators

    Hi Luzell, Sorry, but the old 74LS124 was replaced by the improved 74LS629 many years ago. The datasheet tells you exactly what you need and has circuits. Search at Google.com. Hi Kevin, Most commercial function generators use VCOs without phase detectors. The LM331 VCO also works very well. If...
  17. audioguru2

    Generators

    Steven, Are you aiming to produce 1 metre arcs? That'll take lotsa volts. Have you tried spraying a fine water mist between your charged electrodes?
  18. audioguru2

    Generators

    Hi Steven, Your generator puts out quite a high AC voltage. Of course, your voltage multiplier will have much more, but DC (doesn't it have rectifiers?). There is a formula for the amount of voltage that is required to arc between terminals in air. It is about 1mm/5KV, or something like that. In...
  19. audioguru2

    Another INVERTER we can talk about..

    Another inverter? Wait 'til you see the "Class-D" one that I'm working on. Sine-wave output with very high efficiency (runs cool). When it's shut-down, it will be protected from the environment and BS by keeping it indoors, and covering its "sensitive" bits in case you spill your drink in it or...
  20. audioguru2

    Generators

    Hi Steven, I have lotsa questions for ya: 1) How much AC output voltage does your microwave-motor generator produce? If you crank it hard, what frequency is its output? 2) Why do you connect the parallel capacitors to the AC output of your generator? The AC voltage is continuously changing in...
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