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  1. audioguru2

    0-30 Vdc Stabilized Power Supply

    Xenobius, Good. I'm glad that you spotted and fixed your problem. So the 2N3055's emitter-base junction was avalanching like a zener diode, in series with the base-collector junction. No matter what voltage the output of U2 was providing, the output could not follow it down. Now you can remove...
  2. audioguru2

    isolated motor feedback circuit

    Bob, 20KHz will be much better and we could choose a faster opamp. Also a logic opto will be faster than the PS2501 linear one. How fast does the current rise in your motor? Do you have a spec for its inductance?
  3. audioguru2

    isolated motor feedback circuit

    Bob, The motor, opamp and opto delays are: 1) The motor is an inductor which will have an unknown delay. 2) The opamp has delays of 10 microsec. for rise, and 10 microsec. for fall. 3) The PS2501 opto has delays of 3 microsec. for rise and 5 to 20 microsec. for fall. Since these delays exceed 1...
  4. audioguru2

    Dual LM3886 Bridged Amp.

    Hotwaterwizard, Yes, the disaster damage ratings are probably logarithmic just like your hearing's response to sound levels. Your eyes' response to brightness is also logarithmic. I made 3 triangle-wave generators to feed their linear ramps to red, green and blue LEDs, similar to the circuit in...
  5. audioguru2

    isolated motor feedback circuit

    Ante, I revised your circuit only because Bob needs to detect a motor current of 1A and more. Your circuit's LED current stays zero until the motor current exceeds about 2.8A. Regarding the opamp type, anyone using an old 741 in our circuits here will be very disappointed.
  6. audioguru2

    0-30 Vdc Stabilized Power Supply

    FireFly, Yes, the 44V rated TLE2141CP is a good substitute for the TL081 in this project.
  7. audioguru2

    isolated motor feedback circuit

    OOOps, I always make this mistake: The gain of a non-inverting opamp is 1 PLUS the resistor ratio, so when 6A of current flows in the sense resistor then the voltage at the LED's cathode is 3.3V. If R2 is 910K then the voltage will be 3.03V.
  8. audioguru2

    isolated motor feedback circuit

    Let me try attaching it again: ;D
  9. audioguru2

    isolated motor feedback circuit

    Ante, I am sorry but your circuit has problems: :( 1) The opto won't be active until the current through the sense resistors exceeds about 2.8A. 2) The opamp's output will be 3.63V with 6A of current through the sense resistors. 3) R2-2 is not needed when using a 324 quad opamp. 4) You show the...
  10. audioguru2

    detector prototype

    I said that already:
  11. audioguru2

    "Notify of Replies"

    Ante, It depends on whom you ask. The marketing department of my ISP says one thing, and Microsoft and Bandwidthplace.com say another. But it is very, very fast.
  12. audioguru2

    detector prototype

    If Ante's idea works, then mine will too.
  13. audioguru2

    Mist MAker Via Oscilloscope???

    InFLak, The piezo doesn't need triangle or sine-wave drive, a 555 or CMOS oscillator can drive the BU406 transistor. You don't need an H-bridge. Just copy the output wiring of the original. If the BU406 is bad then replace it with a good one.
  14. audioguru2

    detector prototype

    Ante, Your circuit has a very good use of the very high input impedance of a CMOS chip. Do you think that it works as a capacitor voltage divider, with its antenna as a plate of a capacitor between the mains voltage and ground? Try it with an inverter as the input, which connects to a bunch of...
  15. audioguru2

    Mist MAker Via Oscilloscope???

    InFLak, You are correct that 2.7ms is 370Hz. Perhaps the ultrasonic vibrations are produced in bursts, with a burst-rate of 370Hz. The time of the pause between bursts will allow the water to re-coat the piezo. As you say, maybe the piezo resonates like an LC circuit at a very high frequency. It...
  16. audioguru2

    KA7812

    Yourwins, The 7812 is a 12V regulator with many transistors and resistors inside. A multimeter cannot measure if it regulates properly, but can tell only if it is shorted. I don't think that it can measure the difference of one that is blown open. The best way to test it is when it is...
  17. audioguru2

    Dual LM3886 Bridged Amp.

    Hotwaterwizard, Never mind talking about PEAK. Peak power (also called maximum power) is just a method for marketing-guys to get a number that is doubled, since the power at the peak of a sine-wave (1.414 times its RMS voltage) is twice (1.414 squared) as much as RMS power. That's why a...
  18. audioguru2

    Dual LM3886 Bridged Amp.

    Hotwaterwizard, Of course you can tell the difference between 5W and 20W, it is 4 times the power and a 6dB difference. But from 30W to 50W is a very small loudness change, only a little more than 2dB. You made a very good point about the speaker's box matching the speaker. If the match is poor...
  19. audioguru2

    Led display Digital Voltmeter question

    Nick, Ante's circuit in his reply #37 above, is a cheap and simple way to get -5V.
  20. audioguru2

    s-video + audio to VHF/UHF (antenna cable)

    Fudy, Instead of building a TV station for your cables, simply move the vhsplayer to your TV and use your spare TV cables to connect the stereo audio back to your remote amp. This should work if the audio source has a low output impedance, otherwise the sound's high frequencies will roll-off due...
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