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  1. audioguru2

    UNIVERSAL BATTERY CHARGER/DISCHARGER(PLZ help)

    To know how it works, first you need to learn about electronics. Then you should look at the datasheet for the CD4536 timer to learn how it works and what it does. Then you need to learn about transistors and opamps. Your teacher should teach these things to you.
  2. audioguru2

    measure power in reactance component

    A reactance doesn't dissipate power. The tiny amount of resistance inside it dissipates a small amount of power. The reactance charges and discharges with AC current which is called "apparent power". Apparent power is explained in articles in Google about Power Factor.
  3. audioguru2

    Electronic Stethoscope 2

    Hi Greg, Mylar is a plastic film. Capacitors are made from it when they metalize one side of it. An oriental "green cap" is also a metalized plastic-film capacitor and I have seen orangish-brown ones. 0.047uF is marked "473". 5% tolerance is marked "J". So you need capacitors marked "473J". Hi...
  4. audioguru2

    Graphic equalizer

    Hi Bassanova, Hearing damage occurs if continuous 80dB sounds are heard. 80dB is not very loud. The damage is mechanical, The tiny hairs in the inner ear that attached to nerves are broken by loud continuous sounds or very loud short duration sounds like from guns or from hammering. The...
  5. audioguru2

    Guitar pre-amplifier to amplify to line level

    A guitar pickup has an output level far higher than a magnetic phono cartridge. A phono preamp for a magnetic cartridge boosts the bass frequencies because the bass is reduced when a record is cut. Then the phono preamp is easily overloaded at bass frequencies. Maybe an overloaded phono preamp...
  6. audioguru2

    white led

    Hi Pier, I think a transformer is designed to allow a 10% mains over-voltage.
  7. audioguru2

    Graphic equalizer

    A real hearing aid would limit the volume of the signal so that hearing damage does not occur. The volume of a sound that is far less than a level to cause discomfort will damage hearing. So I think that the person with hearing impairment who has a real hearing aid will hear a very loud sound as...
  8. audioguru2

    Graphic equalizer

    You will probably make the hearing impairment worse. Boosting loud sound levels will damage hearing. Real hearing aids have a compressor/limiter to clamp the levels to a safe level. Simple diode limiters and signal clipping will add high level severe distortion that is also bad. Here is a...
  9. audioguru2

    white led

    A low mains voltage won't harm a transformer. A reasonably high voltage is also fine. A gross overvoltage (lightning, high voltage by mistake or by accident) would fry a transformer. Most overvoltage protection devices conduct to blow themselves up or to blow a fuse.
  10. audioguru2

    Ft of the transistor

    My transmitter takes the oscillator's output from its emitter. Many other FM transmitters take a higher level oscillator signal from the collector or from a tap on the coil for a higher output power. I didn't try it.
  11. audioguru2

    turnsignal and brakes

    Only the criminals in Canada own guns. Most of the criminals and most of the guns are American. Criminals in Canada don't modify lights on their cars. Just teenagers do and they get caught by the cops.
  12. audioguru2

    Adjustable Voltage Reg LM317, Should it be getting this hot ?

    No, they all have thermal shut down because they all use the same chip. National Semi supplies the LM317 in 7 different packages. The T is the TO-220 package, the K is the TO-3 package and there are a few tiny surface-mount packages.
  13. audioguru2

    help with solid state relay

    One-quarter Watt resistors will be fine. The semiconductors are seriously damaged if you look at them too hard. ;D
  14. audioguru2

    Ft of the transistor

    Nope, I didn't scope my FM transmitter. My scope doesn't go that high and its input capacitance might load the circuit too much. I have seen scope photos of similar circuits producing a 30V peak at the output. Way higher than the supply voltage. The transistor becomes completely cutoff.
  15. audioguru2

    hellp.........

    Use a counter/decoder like a clap on-off circuit. Then when you say O-PEN, the door opens. When you say CLOSE, the door closes. When you bark twice, the door opens. When you bark one time, the door closes. ;D ;D
  16. audioguru2

    12v to 230 volts dc with voltage doubler circuit its possible?

    The author's forum nas hundreds of complaints about this lousy inverter: 1) Its capacitors are backwards so they blow up! 2) The transistors have an absolute max reverse emitter-base voltage rating of only 7V but when this circuit supplies them with 12V then the emitter-base junctions have...
  17. audioguru2

    help with solid state relay

    0.5 ohms is nearly a dead short. The MOC3041 will blow up! Use 47 ohms. Yes, it turns off the triac. The triac won't work if MT1 and MT2 are reversed. Use DC from about 3V or more to turn on the LED through the current-limiting resistor.
  18. audioguru2

    help with solid state relay

    The datasheet for the MOC3041 says that an LED current of 15mA will trigger all of them. It is the minimum LED current. If your resistor value is 5% high then some MOC3041's won't trigger. The datasheet recommends using an LED current between the minimum of 15mA and the maximum of 60mA. Ante's...
  19. audioguru2

    Electronic Gun !!!!!!!!!

    Hi Shantanu, Electrolytic capacitors have a vent on top to slowly release gasses that build up when the capacitor is connected with backwards polarity then has a high current. With a very high current, the vent cannot release the gasses slowly so the capacitor explodes. A 9V battery cannot...
  20. audioguru2

    Redesign Elektor gigant2000 Amplifier

    I wish I have all the documents written by Self. His article in Wireless World magazine probably has more details.
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