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  1. audioguru2

    Parsing My Bicycle Tail Light

    it has a custom-made circuit and I doubt it can be fixed. Just add your own on-off switch to it.
  2. audioguru2

    Jacob's Ladder

    A flyback transformer drives the deflection coils that makes the beam move left and right. If you don't know which pin is which and don't know if its high voltage is AC or DC then how can you use it to make a Jacob's Ladder?
  3. audioguru2

    circiut help reqest

    The circuit will work fine with just about any opamps. TL082 dual opamps are made exactly the same by many companies, look at the datasheet to see which pin is which. Most other dual opamps have the same pins numbers. The circuit is designed to be powered by two 9V batteries, one for +9V and...
  4. audioguru2

    SN84LS123

    It is a 74LS123.
  5. audioguru2

    newbie question

    What kind of LCD display consumes 250ma? It must have a very bright light in it. A little 9V alkaline battery can supply 250mA for only a short amount of time. The low dropout 5V regulator will work fine for a little more than one hour. The circuit diagram for the low dropout 5V regulator is in...
  6. audioguru2

    Replacing IGBTs with BJTs in Elektor IGBT design!

    Hi Shahriar, Look in Google at Sziklai Pair to see the complementary transistors connected to operate like a high power single emitter-follower. Usually an emitter resistor is used to match the transistors at the top and at the bottom and for thermal stability to avoid thermal runaway.
  7. audioguru2

    what resistor?????

    The value of a resistor and its power rating is calculated from how much current there will be in it and how much voltage there will be across it. You didn't say how much current so we can't calculate a resistor. An appliance made for 110V to 120V should work fine with 123V since it is only...
  8. audioguru2

    0-30 Vdc Stabilized Power Supply

    If R7 is 0.47 ohms then the max output current is supposed to be 3A but people say it is higher. 0.51 ohms will reduce the max current which might be 3A or a little higher. Try it.
  9. audioguru2

    Can someone suggest a good 50 to 75Ohm impedance matching transformer?

    Hi Dot-com, Isn't your FM antenna just a whip? It impedance is affected by the size of its ground plane and anything that is near it. It might already be 50 ohms. A transformer will have some loss. The loss will be about the same as a small amount of loss from the impedance mis-match so you...
  10. audioguru2

    white led

    Making a comparator detect that the mains voltage is too high is simple, but giving it a reference voltage is difficult. An LM10 is a voltage reference with an opamp and can be used. Can you get one?
  11. audioguru2

    Headlight Flasher

    I thought car headlights are 60W and draw 5A to 6A when hot, and draw 50A to 60A when cold. They are turned on by a big strong relay. A 3A relay would be a tiny little thing and wouldn't even be needed since the switch could turn on a little 3A light without a relay. If I select a Mosfet that I...
  12. audioguru2

    Question: Can computer burn your house down?

    Anything that is electrical can cause a fire, but it would be unlikely. There are some parts in a pc that could fail which would cause a current through another part that causes too much heat. Then the part could catch on fire and set other nearby parts or plastic things on fire. Get homeowner's...
  13. audioguru2

    Voice activated switch used in noisy conditions

    It is difficult to separate noise from a motorcycle and from voice sounds. They are both in the same frequency band and the motorcycle noise might be louder. Good luck.
  14. audioguru2

    Replacing IGBTs with BJTs in Elektor IGBT design!

    Hi Shahriar, The schematic with IGBTs is a fuzzy JPG file type and its details cannot be seen even when it is zoomed. It is too bad it wasn't saved as a very clear GIF or PNG file type. The circuit in the 2nd schematic is unusual because its output transistors don't have emitter resistors.
  15. audioguru2

    Question for Electrician about unsafe voltages

    Some electrical outlets in my home were wired wrong by a drunk (?) electrician.
  16. audioguru2

    Question for Electrician about unsafe voltages

    Don't blame the electrician. He works with AC so he doesn't know anything about DC polarity.
  17. audioguru2

    AudioGURU and others... help me!!!!

    You need to learn about the details of electronics and about the parts that are used in circuits to be able to design circuits. There are tutorials in our Articles section and on the internet about what each part in a 555 oscillator does. The datasheet also explains about what each part does...
  18. audioguru2

    Need Help Voltage Regulator 12 vDC using 7812

    A 24V center-tapped transformer can be used with only 2 rectifier diodes. A 12V transformer needs 4 rectifier diodes to make the same DC voltage. Then its load can be nomore than 12VA. It makes a DC peak voltage of 17V so the max DC output current is 12/17= 0.71A. You could make your own voltage...
  19. audioguru2

    Microphone Amplifier

    You cannot connect anything directly to both inputs of an opamp because the voltage gain would be 200,000 at low frequencies which is way too high. The opamp needs to have negative feedback to reduce the gain to a usable amount. The inputs of an opamp also need to be biased correctly. Look in...
  20. audioguru2

    free energy motor

    1) Connect the shaft of a DC motor to the shaft of a DC generator. 2) Connect their wires together. 3) Give the shafts a spin to make the generator to generate electricity for the motor to use. Then the motor drives the generator like magic. Without any other loading, how long will the motor...
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