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  1. audioguru2

    Need help with 3916 super project

    Hi Supes, Welcome to our forum. ;D The LM3915 and LM3916 ICs are DC voltmeters. In your circuit the input voltage for all 10 LEDs to be lighted is only 1.25V. Your input voltage is 6.9V (DC?) when it should be 0V without signals. An LM358 opamp should work in my circuit but it has reduced...
  2. audioguru2

    Need help saturating a transistor for 2 amps

    A single transistor saturates well with a low voltage drop of 0.05V to 1V. A darlington transistor doesn't saturate, it just turns on and its voltage drop is 0.6V to 2V.
  3. audioguru2

    Knight Rider with Halogen Bulb

    Transistors should always have a resistor or circuit between their base and emitter to turn them off. Without anything, then heat or a nearby radio transmission will turn them on or keep them on.
  4. audioguru2

    A project, help

    Gate inputs must be connected to a DC voltage, so I added pull-down resistors for a logic low at rest. You had the LED connected so "set" would turn it off the first time. I have it so it turns on. A "power-up reset" circuit could be added.
  5. audioguru2

    A project, help

    Use capacitor coupling. It will give a short duration input pulse no matter how long the input stays. Then the NOR gate flip-flop's inputs also need pull-down resistors. Then the supply voltage for the gates of the flip-flop should be the same. Ordinary Cmos gates work with a supply voltage down...
  6. audioguru2

    How can I make a guitar fuzz effect

  7. audioguru2

    Need help saturating a transistor for 2 amps

    The datasheet for the NTE transistor doesn't have any curves and has only a few spec's. Its "saturation" voltage is pretty high at a max of 2.0V with a 5A load and 1/250th of its collector current as its base current. I guess its input voltage is 2.5V max at 5A. Who knows what they are at 1.6A...
  8. audioguru2

    How can I make a guitar fuzz effect

    No it doesn't! The negative feedback in an inverting opamp circuit creates a "virtual ground" at its inverting input where the input and output signals cancel. Therefore the input impedance is the input resistor.
  9. audioguru2

    How can I make a guitar fuzz effect

    I think that guitar pickups need a high impedance load like 1M ohms. The clipping opamp circuit has an input impedance that is very low at 1k ohms. The heavy loading on the pickup reduces its level.
  10. audioguru2

    PROBLEms of LM317

    Simply use two LM317 ICs. One is the main regulator and the other makes a perfect -1.2V for it. Get them with the same date code so they are nearly the same.
  11. audioguru2

    battery and HDD

    Where do you buy lousy resistors that change their value? I use cheap carbon film resistors that don't change, and also pretty cheap metal film resistors that are even better. No problem.
  12. audioguru2

    battery and HDD

    The emitter resistor shouldn't be there. It causes the transistor to current-limit with a current too low. The base resistor in datasheets is 3.0 ohms.
  13. audioguru2

    Transistor tester

    The transistor tester circuit is too simple to make a detailed test. It doesn't even test the current gain of the transistors.
  14. audioguru2

    A project, help

    Look at "set, reset flipflop" in Google. It shows that a NAND gate flipflop won't work with your high signals, it works with low signals. You need a NOR gate flipflop. The signals to a gate flipflop must be momentary. If an input signal stays then the other signal won't work.
  15. audioguru2

    Transistor tester

    Hi Steve, If the tested transistor is shorted from collector to emitter, then two diodes in series will be across each LED. Two diodes limits the voltage to 1.3V but a LED needs 1.7V or more to light so the LEDs will not light. If the tested transistor is open then the LEDs will flash like it...
  16. audioguru2

    Current monitor/sensor

    You didn't say if the current is AC or DC, and you didn't say how much current or voltage.
  17. audioguru2

    6V 5A PSU problem.

    4mV to 8mV of ripple on an unregulated supply is very, very low. You must have measured it without a load. Load it with 1A and the ripple voltage will be more than 1Vp-p. You said your transformer is rated at 24V-0V-24V? Then its unregulated DC voltages should be about 32VDC.
  18. audioguru2

    4 watt transmitter

    This kind of confusion wouldn't happen if you make a link to the project or attach the schematic.
  19. audioguru2

    circuit converse High voltage AC to DC

    I wonder where the 50kVAC is going to come from. Is he going to connect his own wires to the electical company's high voltage transmission lines? I also wonder what he is going to do with the resulting 70.7kVDC.
  20. audioguru2

    12 V DC to a 220V AC Inverter AMplfier Design

    A square-wave inverter 's output goes: positive pulse, negative pulse, positive pulse again, negative pulse again and repeats. A simple modified sine-wave inverter's output goes: positive pulse, 0V pause, negative pulse, 0V pause, positive pulse again, 0V pause again, negative pulse again, 0V...
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