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  1. audioguru2

    Audio meter with 1 watt Luxeons

    Connect a PNP 2N4403 transistor to the LM3915 and current limiting resistor and Luxeon LED like this:
  2. audioguru2

    Decreasing bug antenna size

    They say that a 170cm single wire antenna wire is half-wave but they are wrong. It should be 80cm to 85cm for the center of the FM band. You can shorten the antenna wire and all that will happen is that the range will be reduced.
  3. audioguru2

    7555 ic

    An ordinary 555 timer IC has ordinary bipolar transistors, needs a min supply voltage of 4.5V, has a fairly high operating current and has a high sink or source 200mA output current. A Cmos 555 timer IC has Mosfet transistors, needs a min supply voltage of only 1.5V, has a fairly low operating...
  4. audioguru2

    amplify the power (infrared)

    Hi Ryan, Your opamp doesn't have its pin 4 connected! It also doesn't have a supply bypass capacitor. Your circuit doesn't have much gain: 1) The collector load resistor for the phototransistor's value is much too low. 2) The inverting opamp's input impedance of 10k is loading-down the...
  5. audioguru2

    Op-amp or trans-impedance amplifier

    I can't read the frequency. Are you modulating the IR beam and need to filter it? A 741 opamp doesn't work very well above 9kHz, use a newer opamp with a much higher frequency response.
  6. audioguru2

    a 43yr old e-God, steven

    I hope you have a nice Happy Birthday, Steven.
  7. audioguru2

    Op-amp or trans-impedance amplifier

    Hi Zhiling, Welcome to our forum. ;D I got these photodiode circuits from somewhere.
  8. audioguru2

    Plants Watering Watcher-2 by Audiguru

  9. audioguru2

    TV Disrupters and Cellphone jammers

    Cell phones use many RF frequencies. If your jamming transmitter operates on one of those frequencies then the cell phones will work fine on the other frequencies. If you sweep the RF fequency of your jamming oscillator or just make random RF noise then it will need a lot of RF power and will...
  10. audioguru2

    help in transmitter

    You can feed an RF amplifier from the oscillator's collector or from its emitter. You can bias the RF amplifier from the positive supply or from ground where it will operate in class-C.
  11. audioguru2

    Audio meter with 1 watt Luxeons

    Hi CK, Welcome to our forum. ;D You will need a power supply cabable of supplying 3.5A for your project. I haven't seen a 9V supply with such a high current so you can make one yourself from a 12V cener-tapped 5A transformer, a 10A pair of rectifiers and a 4700uF filter capacitor. PNP...
  12. audioguru2

    audioguru fm transmitter

    The RF amplifier transistor Q3 might already operate a little in class-C if the oscillator signal is strong enough. The base-emitter junction could act like a rectifier and charge C12 so that Q3 is cutoff a little. If R8 is connected to ground instead of to the positive supply then Q3 will...
  13. audioguru2

    Plants Watering Watcher-2 by Audiguru

    Sorry, I got my text mixed up. IC1-B is a 2kHz oscillator and IC1-D is a NAND gate.
  14. audioguru2

    audioguru fm transmitter

    Yes, my transmitter's Q3 produces a little heat with a brand new 9V alkaline battery. I can't remember exactly but the supply current was about 55mA so the power from the battery was 495mW. The preamp and oscillator doen't use much supply power so most must be used by Q3, 230mW as heat and 230mW...
  15. audioguru2

    geophone kit circuit reqest

  16. audioguru2

    geophone kit circuit reqest

    Hi Steven, A 741 opamp won't work properly with its non-inverting input pin 3 connected to the negative supply voltage. Pin 3 should be biased to a voltage that is half the supply voltage with a voltage divider made with two series resistors. Then pin 3 should have a bypass capacitor to the...
  17. audioguru2

    system operation

    I think the circuit is a "clap switch". It switches on the relay when you clap your hands a few times that are determined by the flip-flops.
  18. audioguru2

    Plants Watering Watcher-2 by Audiguru

    Hi Walid, Your formula is for an ordinary Cmos oscillator. A Cmos oscillator with a Schmitt trigger has a different formula. A Cmos Schmitt trigger switches when its input voltage is fairly close to zero volts while an ordinary Cmos oscillator switches when its input voltage is close to half of...
  19. audioguru2

    My Computer Crashed Again

    Hi Staigen, What do you think went wrong? Hardware or software?
  20. audioguru2

    geophone kit circuit reqest

    Hi Steven, In your circuit, the LED has nothing to limit its current and could easily burn out. The diode in series with it is doing nothing and should be changed to a 300 or 330 ohm resistor to limit the current to about 24mA. Also, the 2nd transistor is doing nothing and should be removed...
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