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  1. audioguru2

    RC-(remote controlled) Car

    It looks nice, BUT: Your varactor diodes are forward-biased. They are supposed to be reverse-biased. You should turn them around.
  2. audioguru2

    Power dissipation limiter

    Hi Ante, The circuit is complicated. I bleached away most of the dirty paper towel that you had it printed on.
  3. audioguru2

    Audioguru FM Tx

    Hee, hee.  ;D I don't know about international laws, but I think the RF cops would even arrest you on your own island if you cause interference to radio stations. Your island would need to be in your own country. Where can you buy a country???
  4. audioguru2

    project help with toy IC boards

    Use a 9V battery so the LM386 power amplifier drives the speaker loud enough, then reduce the voltage to 3V with an LM317L adjustable voltage regulator. The LM317L is small and needs just two small capacitors and two resistors. The ratio of the resistors sets its output voltage. The message...
  5. audioguru2

    amplify..

  6. audioguru2

    12 V DC to a 220V AC Inverter AMplfier Design

    The input pulses to the gate of each Mosfet are a high voltage (12V) so the Mosfet turns on as hard as it can. The Mosfets are switches, not amplifiers. Amplfiers get too hot for an inverter.
  7. audioguru2

    0-30 Vdc Stabilized Power Supply

  8. audioguru2

    Electronic Stethoscope

    Hi Priyank, Maplin don't have a detailed spec on that page for the response of the mic. The FAQ has a question, "How flat is the frequency response?" but I couldn't find the answer. Ask them. Panasonic makes many electret mics which were available somewhere in North America. Their cheap one has...
  9. audioguru2

    Infrared Receiver

    Hi Axle, Your circuit doesn't show the polarity of the photo-diode, or the collector and emitter of the transistor. It looks like it is an emitter-follower. Right? Your simple circuit responds to any kind of light or IR. IR remote control systems modulate the beam with a high frequency carrier...
  10. audioguru2

    Audioguru FM Tx

    Up to 1W output with low harmonics is perfect. Now all you need is a ship for you to be a pirate radio station.
  11. audioguru2

    RC-(remote controlled) Car

    It is good to hear that your transmitter's RF frequency doesn't drift much. The MPSH10 is in a small case (low power dissipation) and has a low max voltage limit. I hope it doesn't break. Won't your transmitter cause interference to FM radios and TVs? Won't your receiver pickup FM stations?
  12. audioguru2

    need help for cfl lighting

    A compact fluorescent light needs a ballast to make it work. A very old ballast was a big coil of wire as an inductor, then it had a starter with mechanical contacts or a small neon bulb. Modern ballasts are an electronic circuit with a power oscillator driving a high frequency small stepup...
  13. audioguru2

    Audioguru FM Tx

    The strong 2nd harmonic will mess-up a TV channel from channel 7 to channel 13 and get those RF cops running to arrest you.
  14. audioguru2

    RC-(remote controlled) Car

    What kind of battery are you going to use for the transmitter?
  15. audioguru2

    Infrared Receiver

    No it won't. It doesn't even need a carrier frequency. The sound can directly modulate the light or IR beam. A carrier is used with IR so that other sounds can also be transmitted at different carrier frequencies for stereo. Also, a high carrier frequency allows a highpass filter to remove buzz...
  16. audioguru2

    Infrared Receiver

    Hi Axle, Welcome to our forum. ;D You didn't attach the schematic of your circuits so it is difficult to see how you connected them. A photo-diode can be revese-biased with a voltage through a high-value resistor and doesn't conduct without IR radiation. With IR radiation on it then it conducts...
  17. audioguru2

    Power dissipation limiter

    Q2 is the series pass transistor in our "Variable DC Power Supply" project, the one that doesn't have a voltage reference and so I call it a thermometer.
  18. audioguru2

    RC-(remote controlled) Car

    Your radio is tuned with a variable capacitor, so it doesn't have a quartz crystal nor a PLL. It ceramic resonator shapes its IF wideband response curve. Your transmitter's RF frequency will drift with temperature change of its transistor and parts, with changes in its supply voltage and when...
  19. audioguru2

    Power dissipation limiter

    It looks like it will work! Good idea. ;D
  20. audioguru2

    RC-(remote controlled) Car

    Your coils look good. Does the wire have enamel insulation on the ferrite-cored coils? It looks like bare wire. The frequency of this transmitter will drift all over the place. RC cars, planes and boats use a quartz crystal in their transmitter for frequency stability. Some also have a quartz...
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