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  1. audioguru2

    need the function generator circuit

    There were some function generator ICs available some years ago but maybe they are not made anymore. Will your teacher let you use one? "Tek_" on another electronics chat forum says it must be a circuit made with opamps. Must your function generator be made with opamps? It is easy to make a...
  2. audioguru2

    What is a voltage regulator?

    Most voltage regulators are a "series linear" design and they waste the extra voltage as heat. The 78xx series and the LM317 are series linear regulators. They need an input voltage at least 2.5V higher than their regulated output voltage for their internal circuit to work properly. Switching...
  3. audioguru2

    Cell Phone "AA" BATTERY Replacement...

    Are you planning to run your cell phone from throw-away alkaline battery cells, instead of using a rechargable battery? Are you foolish and rich? AAA cells have less than half the capacity of AA cells and AAAA cells or a 9V battery (it has 6 AAAA cells inside) have 1/5th the capacity of AA cells.
  4. audioguru2

    Cell Phone "AA" BATTERY Replacement...

    Two AA battery cells supply a voltage of from 2.0V when old, to 3.1V when new. Devices that use this as a battery must be designed for the range of voltages or they won't work, will they? A guy posted a circuit on the web that uses an ordinary Cmos gate IC that has a minimum operating voltage...
  5. audioguru2

    Cell Phone "AA" BATTERY Replacement...

    Two AA battery cells are 3V only when they are new. Their voltage quickly drops to about 2.4V then slowly drops to 2.0V. I don't think your cell phone will work with a battery that is between 2.0V and 3.0V. Where are you going to put a dc-dc converter circuit?
  6. audioguru2

    Astable multi vibrator, some help?

    If you remove the LEDs and short the connections where they were then the circuit will work fine with the original 470 ohm values for R2 and R5.
  7. audioguru2

    How can I make a guitar fuzz effect

    MP, you have shown that you don't know about the input impedance of opamp circuits. An inverting opamp circuit has a very low input impedance provided by its input resistor. A non-inverting opamp circuit has a very high input impedance provided by its DC-reference-voltage resistor to ground...
  8. audioguru2

    Astable multi vibrator, some help?

    With R3 and R4 connected directly to +5V, the oscillator operates as fast as it can which is the same as when the pot is turned to its max speed. If you want the speed to be faster then reduce the value of the capacitors. Half their value will double the speed.
  9. audioguru2

    Astable multi vibrator, some help?

    You should not connect the base and emitter of two transistors together. One will have a slightly lower voltage and work, and the other won't work.
  10. audioguru2

    Need help with 3916 super project

    It is too bad that you didn't find the problem yet.
  11. audioguru2

    How can I make a guitar fuzz effect

    National Semiconductor discontinued making their LF351 opamp. I have been using the Texas Instruments TL07x series of audio low noise opamps. This guitar preamp circuit has a gain of 101, fuzz diodes and an input impedance of 1M:
  12. audioguru2

    Audioguru FM Tx

    A 7805 works fine with an input voltage of 7.5V or more. A cheap radio overloads and makes the transmitter appear at many places on the dial. My Sony Walkman FM radio does only when its antenna is switched to Distant. It does not overload when it is switched to Local. My homw stereo tuner and...
  13. audioguru2

    12 V DC to a 220V AC Inverter AMplfier Design

    A d-to-a converter creates an analog sine-wave so the efficiency is the same as an analog power amplifier, about only 60%. You lose nearly half the battery power. It would be the same if a Wien Bridge or any other kind of analog sine-wave oscillator is used.
  14. audioguru2

    0-30 Vdc Stabilized Power Supply

    U3 is supposed to compare the voltage across R7 caused by the load's current, with the voltage from P2 which is from nearly nothing to 1.7V. With P2 at max and the voltage from P2 at 1.7V then U3 does nothing until the voltage across R7 is slightly more than 1.7V which would be caused by a load...
  15. audioguru2

    0-30 Vdc Stabilized Power Supply

    Then R21 connects to the wrong end of R7.
  16. audioguru2

    0-30 Vdc Stabilized Power Supply

    Opamp U3 is used for current regulation. It compares the voltage across R7 (which is caused by load current) to the voltage of the current adjustment pot P2. Its pin 4 must be about -5.6V or it won't work correctly.
  17. audioguru2

    12 V DC to a 220V AC Inverter AMplfier Design

    Sketch the circuit of a modified sine-wave inverter and I will check it for you. Don't forget the transformer must have an output voltage about 1.414 times higher than the transformer in a square-wave inverter, to create the peak voltage of the sine-wave. Therefore instead of a 230V to 24V...
  18. audioguru2

    12 V DC to a 220V AC Inverter AMplfier Design

    Sorry, I had the pin number of the clock for the CD4047 wrong. I fixed it. Connect the pin 13 and pin 10 to one gate of a CD4011 which drives the 1st Mosfet. Connect the pin 13 and pin 11 to another gate of the CD4011 and it drives the 2nd Mosfet. At only 50Hz or 60Hz, I don't think the...
  19. audioguru2

    Need help with 3916 super project

    I think you posted the voltages at the pins of the dual opamp. Its Pin 1 has a very high AC output voltage and the 2nd opamp and transistors should rectify it and amplify it but they don't. Check C4 (330nF which is 0.33uF), R9 (56k) and R8 100k). Check that the emitter of one of the transistors...
  20. audioguru2

    12 V DC to a 220V AC Inverter AMplfier Design

    I already told you how to connect a CD4047 with logic gates that drive your Mosfets with a modified sine-wave. The timing diagram looks like this: EDIT: Corrected the clock's pin number.
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