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  1. audioguru2

    Redesign Elektor gigant2000 Amplifier

    Hi AN920, I don't have the book by Douglas Self that you have. I have only his article about Distortion In Power Amplifiers on the web. He shows a "blameless" amplifier designed by him and he claims it has 0.002% distortion from 10Hz to 20kHz when it is biased as class-A. But none of his...
  2. audioguru2

    Sound Level Indicator

    Hi Jon, My Sound Level Indicator uses a "9V" rechargable Ni-Cad battery that is really only 7.2V because it has six 1.2V cells. It is almost always fully-charged at 8.5V. The Ni-Cad battery powers it for about 20 minutes with the brightness control at max (26mA for each LED) and a loud signal so...
  3. audioguru2

    Redesign Elektor gigant2000 Amplifier

    Hi AN920, I was quoted but I said only the 1st quote. Douglas Self has an article "Distortion In Power Amplifiers" on the web at http://www.dself.dsl.pipex.com/ampins/dipa/dipa.htm In it he frequently says "class-B" by mistake when he is talking about "class-AB". He shows the schematic of a...
  4. audioguru2

    Two PCBs off of one power source

    The MC34119 is a power amplifier with an output current up to 250ma. An opamp has a max output current of only 20mA and therefore cannot drive a speaker. A power amplifier needs to have an idle current to avoid distortion. The MC34119 has a Chip Disble pin #1 that reduces its supply current to...
  5. audioguru2

    Two PCBs off of one power source

    Hi Bruce, I am uncertain about what you want to do. 1) Turn on the FRS radio and the MC34119 amplifier also turns on. Then when you turn off the FRS radio the MC34119 amplifier also turns off. 2) Momentarily push a TAC switch on the sound effects gadget and the MC119 amplifier also turns on...
  6. audioguru2

    crystal oscillator transmitter

    No. An FM transmitter changes its frequency with modulation. A crystal oscillator's frequency can be changed only a tiny amount so the received demodulated signal would be extremely weak. Take a 1.3889MHz crystal oscillator and modulate its frequency with a max deviation of 1kHz. Then use two...
  7. audioguru2

    audio output transformer connection

    You don't know anything about your transformer. I also don't know anything about your transformer. Look at the datasheet for it from its manufacturer. It will have a picture that shows which pin is which. It will also say what is its impedance ratio that determines how much or how little it...
  8. audioguru2

    need a program to simulate in electronics

    I also noticed that the node numbers are not shown on the schematic.
  9. audioguru2

    Two PCBs off of one power source

    Hi Bruce, In order to add a transistor with a coupling capacitor to replace each diaphram switch, we need to know what the diaphram switch connects to. Hopefully the diaphram switch connects either to the supply voltage or to ground. We need to know if it does and we need to know which one.
  10. audioguru2

    Two PCBs off of one power source

    A transistor with a coupling capacitor can perform the momentary function of the sound effect's diaphram switch to start it playing then it will shut itself off. You need to find out exactly what the diaphram switch does. It might make an input go high or go low.
  11. audioguru2

    Two PCBs off of one power source

    Then I guess the MC34119 amplifier is still bring powered by the battery when the radio and the sound effects circuit are turned off. The MC34119 amplifier should receive its power after the on-off switch.
  12. audioguru2

    Oscillator question

    Hi Walid, I mentioned the obsolete ICL8038 and XR2206 function generator ICs in my reply to his PM.
  13. audioguru2

    another question, regarding non inverting op amp

    A 5V RMS sine-wave has a peak voltage of 7.07V. So the output of the opamp with a gain of 4 will try to be 28.3V peak which is impossible. The output will be severely clipped at 17V peak and will look like a square-wave.
  14. audioguru2

    crystal oscillator transmitter

    Hi Aimans, You cannot change the frequency of a crystal oscillator very much. Then you cannot have wideband FM. But you can use a low frequency crystal oscillator that has its frequency changed a tiny amount, then multiply its frequency many times to end up with wideband FM at 100MHz. You could...
  15. audioguru2

    555 LED flasher circuit?

    The output of a 555 goes low and goes high. So connect an LED in series with a current-limiting resistor from the positive supply to the output and it will light when the output goes low. Then connect another LED in series with a current-limiting resistor from ground to the output and it will...
  16. audioguru2

    need a program to simulate in electronics

    Hi Walid, I am learning the Sw CAD III simulation program by Linear Technology Corp. It is free. It has a pretty big library of components and it is updated frequently. There are a few websites with add-on P-Spice models for many more components for it.
  17. audioguru2

    white led

    I use solid 22AWG wire for most low current wiring and stranded 22AWG wire for flexible wires.
  18. audioguru2

    Guitar pre-amplifier to amplify to line level

    Hi Ben, The Kemo M040 preamp is designed for low level, low impedance microphones, not high level very high impedance guitar pickups. Here is a simple guitar preamp without much gain (only 1.4) and it has a 3M ohm input impedance: http://www.till.com/articles/GuitarPreamp/
  19. audioguru2

    Dual Power supply

    Please provide more detail, maybe on an attached schematic. What is a "dual power supply"? Is it a positive supply and a negative supply? Shorting one does not affect the other.
  20. audioguru2

    need help power supply

    Separate power supplies are completely separate. Shorting one has no effect on the other.
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