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  1. CircutScoper

    Transistor as a switch

    Ah yes -- the classic and ever popular "smoke test." I was also fond of a similar criterion: When the leads become incandescent.
  2. CircutScoper

    Transistor as a switch

    Current flow into the base/emitter junction of a bipolar transistor is an (approximate) exponential function of the applied voltage, increasing by roughly a factor of 10 for every 60mV above threshold, which for silicon is roughly 0.6V. So yeah. Since 10^((5 - 0.6)/0.06) = 10^73, it would be...
  3. CircutScoper

    I Want to Create a Revolutionary Table Fan!

    You say you want to reduce fan power consumption by 90%? No problem. Nothing simpler. Make it BIG -- and SLOW. The cooling potential of a stream of air is proportional to its mass = density x area x velocity, but its kinetic energy, and therefore the power required to accelerate it, is...
  4. CircutScoper

    Generator & Battery in Parallel

    And trust. Maybe it worked in simulation.
  5. CircutScoper

    Faulty Op Amp...

    Right. I get it -- finally! This "pedal" provides two independent sets of controls -- LEVEL, GAIN, TONE -- that you can set up before beginning a performance, and then switch between while playing. The incoming guitar signal is split between these two channels as well as straight through...
  6. CircutScoper

    Faulty Op Amp...

    Ah so. Then of course any component(s) common to all signal paths is a plausible suspect.
  7. CircutScoper

    Class D audio amp

    You're right of course, but for a given frequency, the slope (dv/dt) of the ramp of a sawtooth of a given amplitude is only half as fast as that of the sides of a triangle. But which augers for better accuracy/fidelity is another question entirely.
  8. CircutScoper

    Faulty Op Amp...

    Okay. I'm confused. The schematic you provided contains only a single opamp while the circuit board pictured contains a dual. So my assumption was that the b'd implements two of the channels illustrated in the schematic, and that the gain loss occurred in both of those two independent...
  9. CircutScoper

    Faulty Op Amp...

    Ya know, if the (unusual) input jack on the DR SWAMP pedal has developed a broken connection, it's not impossible that the intrinsic capacitance of the guitar cable might be acting as a high-frequency filter.
  10. CircutScoper

    Faulty Op Amp...

    Cables too.
  11. CircutScoper

    Faulty Op Amp...

    Since you've said the loss of gain is in BOTH channels and it's unlikely that a failure of any single passive component could affect more than one channel, that seems implausible. A random question: Has the Dr. Swamp pedal worked successfully in the past with EXACTLY the SAME instrument and...
  12. CircutScoper

    Generator & Battery in Parallel

    If the answer is "the motor," I'm outta' here!
  13. CircutScoper

    Generator & Battery in Parallel

    Really? When will the battery be recharged?
  14. CircutScoper

    Faulty Op Amp...

    Well, not to sound skeptical, but can you verify that the input signal is adequate -- by substituting a different signal source or a different "pedal?" I'm not trying to be argumentative but you really have produced some pretty good evidence that this "pedal" is working.
  15. CircutScoper

    Faulty Op Amp...

    Because adjusting the gain pot changes the signal amplitude, it appears the amplifier is working. If it weren't, the pot would have no effect. This implies the cause of your problem may lie external to the pedal circuitry. Are you sure the level of the input signal is adequate? Is it...
  16. CircutScoper

    Faulty Op Amp...

    PS: This might be a quick check of the amplifiers. If your model has something comparable to S1--BOOST, opening that switch would normally (i.e., if the amp were working) "Boost" gain by about 20x = 26dB. But if the amp is dead, the effect of the switch will reverse and opening BOOST will...
  17. CircutScoper

    Faulty Op Amp...

    Hi, Tom Yes. It's certainly possible for a dual opamp chip to develop a defect that would disable both amplifiers. Since you've verified the presence of proper DC voltage on the chip's pins, the next logical step would be to replace it.
  18. CircutScoper

    Projector Power Supply

    Well then, without at least some photos to illustrate the problem, you'll be wanting to check in with the ESP/Clairvoyance forum next door. Sadly, I seen to have misplaced my OUIJA board.
  19. CircutScoper

    Projector Power Supply

    So far as I (a newbie member) has so far discovered, you'll need to upload the picture to a hosting site (e.g. photobucket) and then post a link to it in your thread. Meanwhile, are you saying the OEM internal supply has died and you want, instead of repairing it, to replace it?
  20. CircutScoper

    Detect 5v button push on separate system

    The relay suggestion above is good, especially if you choose a solid state DC relay. For example...
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