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  1. Audioguru

    A zener diode question

    I like Afternoon delight!;)
  2. Audioguru

    Aerial (roof) rotating antenna operation?

    The existing motor should be fine, it needs only two wires for forward and reverse. The signal needs a coax cable. The antenna might need a balun to match it to the coax. About 50 years ago I had the largest TV antenna in my neighbourhood with a rotor. On one channel I could pick up a distant...
  3. Audioguru

    EEG Question on Getting Data to Computer

    It is extremely important to isolate the EEG probes from any mains powered items (the circuit or the computer) to avoid electrocuting the patient. Isolation is usually provided with an optical coupler (LED to photo-diode). Then the input circuit from the probes is battery-powered and it feeds...
  4. Audioguru

    Led Flashlight Help

    I forgot to say that most LED calculators are VERY wrong when the battery voltage is too low for the resistor to do anything. One ohm with 180mA in it has a voltage across it of only 0.18V. The LED's voltage changes more than that when its temperature changes, then the current more than doubles.
  5. Audioguru

    Led Flashlight Help

    A problem with using a current meter in a low voltage circuit is that the meter uses a resistance in series with the load to measure the voltage across the resistor then calculate the current. But the resistor reduces the actual battery voltage and its current. You never power an LED with a...
  6. Audioguru

    Led Flashlight Help

    Measure the voltage of the "4.5V" 3-cells AAA battery when the light is turned on. It is probably only 3V. Then adjust your DC converter to produce the same voltage. My cheap Chinese flashlight has 24 white LEDs and it came with three cheap "Super Heavy Duty" AAA battery cells. When the cheap...
  7. Audioguru

    Radio question. What replaces the LC circuit?

    A quartz crystal is like an extremely accurate LC.
  8. Audioguru

    Aerial (roof) rotating antenna operation?

    The coax cable probably uses DC in it to drive the motor and it changes polarity to reverse the motor. The cable has a coupling capacitor to pass the signal and inductors in series with the motor so that the motor does not short the signals.
  9. Audioguru

    How would make a smelly flatulence (fart) remover for a person with colostomy bag?

    The problem is not with Methane gas. Britannica says, "Methane, colourless odourless gas that occurs abundantly in nature and as a product of certain human activities." I think you are on the correct track by trapping the odor in activated charcoal with a fan. Try it.
  10. Audioguru

    How would make a smelly flatulence (fart) remover for a person with colostomy bag?

    It is Methane gas. Burn it away.
  11. Audioguru

    Forklift LiFePO4

    I think your "battery controller" is a battery charger circuit? Your circuit is designed to charge a lead-acid battery. A LiFePO4 battery is completely different and needs to have a charger circuit that is designed for it to prevent the extremely dangerous lithium battery from exploding and/or...
  12. Audioguru

    Two mic's, one CB

    You forgot to say the microphone type. It could be carbon, dynamic or electret that all have a different input circuit. Also, an electret mic must be powered and a carbon mic must be powered differently but a dynamic mic must never be powered. With two active mics then the transmitted...
  13. Audioguru

    Will this still work with a more powerful motor?

    The datasheet for the L293 says its maximum allowed current is 1A but it is only 600mA for the tiny L293D. Your L293D can drive power transistors or power Mosfets. The power transistors can drive your high current motors.
  14. Audioguru

    LED Circuit Problems

    I have a cheap Chinese flashlight that has 24 white LEDs connected directly in parallel and they are all with the same brightness. Because the manufacturer bought millions of LEDs, tested the voltage on each one and grouped them so the LEDs in a flashlight have exactly the same voltage. The...
  15. Audioguru

    beginner struggling with a opamp

    Your latest circuit does not need R1.
  16. Audioguru

    Forklift LiFePO4

    He wants somebody to look up what the charging specs are for a HiFi traction battery charger and see if the charging specs of the LiFePO4 battery he has are the same. Why doesn't he look the specs up himself? What or who is "BMS"? A LiFePO4 battery needs a charger designed for it.
  17. Audioguru

    Battery charged by a solar panel?

    A battery must be charged at a voltage higher than its average discharging voltage. A battery can have a discharging current much higher than its maximum allowed charging current.
  18. Audioguru

    audio transistor schema...

    Please learn about transistors from a book or from a tutorial in Google. A transistor can be common emitter when the base is the input and the collector is the output with lots of voltage and current gain. A transistor can be common collector when the base is the input and the emitter is the...
  19. Audioguru

    Variable Current Limit with Steady Voltage

    Of course. Probably ahead if the voltage regulator. This current limiter has a voltage drop so the input voltage must add it to the voltage regulator input requirement.
  20. Audioguru

    Variable Current Limit with Steady Voltage

    When you limit the current then the voltage drops according to Ohm's Law. A second LM338 can be used as a current limiter ahead of the voltage regulator. A current limiter and a current regulator are shown on the datasheet of the LM338.
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