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  1. audioguru2

    pulse width modulation

    Kevin, The last circuit uses a Schmitt trigger inverter as an oscillator. Like the other circuits, its duty-cycle is varied with the diodes and pot, to perform PWM. The other circuits use 2 inverters in a classic CMOS oscillator.
  2. audioguru2

    was Re:Ir-remote Now is: Op Amp discussion

    Wired, There are many good discussions about electronics at this place. Please join-in if you have good proof for your arguments, as I have. Kevin, The missing resistor provides a VOLTAGE reference of 0V to the non-inverting input of the opamp, not a current source, since the opamp's input...
  3. audioguru2

    Power MOSFETs

    Power MOSFETs have a very low resistance from source to drain when switched on. But they also have a high gate capacitance. They can swich very quickly if their drive charges their gate capacitance fast enough. Is it true that the chip is simply thousands of little MOSFETs connected all in...
  4. audioguru2

    OUTPUT IMPEDANCE

    Shiva, The meaning of output impedance is the output resistance of an amplifier. The output impedance of most amplifiers is very low, due to their high current ouput transistors and a huge amount of negative feedback. You can measure it by injecting a signal into the amplifier's output through a...
  5. audioguru2

    actually a quad amp....

    ZomBiE, Why do you think that the TDA1558 is better? Its data sheet is here: http://www.semiconductors.philips.com/pip/TDA1558.html#datasheet It seems to have the same case and specs as the TDA1554. Did I miss something?
  6. audioguru2

    Voltage Matching

    Jerry, Welcome to our forum. How much current do you need? Do you have a higher voltage available, so that the "current booster" can have some headroom?
  7. audioguru2

    was Re:Ir-remote Now is: Op Amp discussion

    Well, at least The Guelph University, and National Semiconductor agree with me. Do you think that they will become members?
  8. audioguru2

    digital audio controls

    Savage, You could use DS1669 linear-stepped digital pot chips with the TDA1524A controls chip since the latter converts the linear control to a logarithmic response. But the TDA1524A has a 15 percent dead-band at its low volume end and a 20 percent dead-band at its high-volume end, requiring...
  9. audioguru2

    was Re:Ir-remote Now is: Op Amp discussion

    Ante, Welcome back. No ghosts, just faulty circuits and incorrect statements.
  10. audioguru2

    Displaying amps & volts on 1 display

    FireFly, Big files, the poor guys on dial-up. You are correct, 2 each of the ICM7135 and ICM7211 ICs can be used to display volts and amps on a 16 digit, 7 segment LCD display. Note that this is not a character display. On the ICM7135 datasheet, page 1 shows a simple application, but using the...
  11. audioguru2

    Electronic Stethoscope

    Shiva, You're welcome. I'm glad to help you. Perhaps your computer simulation program doesn't know the circuit's required functions: 1) U2 is supposed to be a classic "Sallen and Key equal-capacitor, equal resistor (requiring its gain of 1.6), Butterworth 2nd-order low pass filter" with a cutoff...
  12. audioguru2

    was Re:Ir-remote Now is: Op Amp discussion

    MP, or your new name, Wired, You're welcome. I'm glad to help members get their theory straight.
  13. audioguru2

    Question on the Plants Watering Watcher circuit

    Hi Guys, After making a bunch of this project but modified my way, I have realised that it is as boring as watching grass grow. It also eats the two AAA alcaline batteries (AA are too big and heavy) in about 3 weeks. So I have decided to spice it up a notch, save battery power and give a low...
  14. audioguru2

    was Re:Ir-remote Now is: Op Amp discussion

    MP and/or Wired, Why ignore me? You might learn something important. You didn't comment on my University Opamp Tutorial, which explained that BOTH inputs should have a voltage reference. My University is well respected, and so is National Semiconductor. In the latter's Application Note #20, An...
  15. audioguru2

    was Re:Ir-remote Now is: Op Amp discussion

    Wired, I am sorry that you disagree with me and my nearby university, from which I recently posted their opamp tutorial. In your quote above, you say that "BOTH inputs on the opamp with bipolar supply are referenced to....... zero volts". I agree, that is correct. Perhaps you have not seen the...
  16. audioguru2

    Led Strobe Circuit

    Hi again, New, Although I wouldn't call an ordinary LED a "strobe" light, I have built projects using ultra-bright LEDs that were powered with 100mA current pulses, and the resulting flashes of light were dazzling, blinding and could be seen for miles. Have you seen the "Dancing LEDs" circuit in...
  17. audioguru2

    was Re:Ir-remote Now is: Op Amp discussion

    Wired, Thanks for joining this discussion, but your statements are confusing: In your 1st paragraph above, you agree with me and my posted tutorial that opamp inputs must not be floating and must be referenced to ground. But in your 2nd paragraph above, you allow a floating input. Are you going...
  18. audioguru2

    Convert 0-30V 3A PSU to 5A or more

    To All, I just got a reply from Hammond, a transformer manufacturer. Their 185G28 transformer is rated for a 115VAC primary, and a 28VAC, 6.25A secondary. They say that its unloaded secondary voltage is 30.39VAC. Therefore its peak voltage is 43.0V, and the lightly loaded rectifiers will drop it...
  19. audioguru2

    was Re:Ir-remote Now is: Op Amp discussion

    To All, I have discovered a very interesting University Tutorial document describing the history, details and applications of opamps. Notice that 2/3 the way down, beside figure 10, the author states, "As a rule of thumb, an opamp circuit will not work AT ALL (his accent) unless both inputs have...
  20. audioguru2

    0-30 Vdc Stabilized Power Supply

    MonSSter, Greetings, and welcome to our community. We have discussed this project and have discovered some problems. We have another post that discusses how correct the problems and to increase its output to 5A. I have recently recommended changes that should allow this. There is a revised PCB...
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