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  1. Audioguru

    Low-frequency High-amplitude piezo driver using ATTiny 85

    They do not measure a sound producer in water to see how soon it corrodes. The movement of a piezo disc is tiny then low frequencies will not do much.
  2. Audioguru

    Low-frequency High-amplitude piezo driver using ATTiny 85

    A piezo transducer is a squeaker, not a speaker. It produces no sound below about 1kHz.
  3. Audioguru

    power supply to 1,5v (clock) AND 3v (LED)?

    The LED must have a series current-limiting resistor.
  4. Audioguru

    555 astable

    A normal 555 astable oscillator circuit charges the timing capacitor through two series resistors but uses pin 7 to to discharge the capacitor though only one of those resistors making the output not to be symmetrical. The 555 uses an old TTL design so then the output high voltage is far from...
  5. Audioguru

    555 astable

    Pin 7 of a 555 is not internally grounded. It actively goes to ground to discharge the timing capacitor when the output pin3 goes low.
  6. Audioguru

    Low power audio circuit design

    The PAM8304 is mono and the PAM8403 is stereo. Yeah, maybe he connected the speaker to one output of the mono PAM8303 or PAM8304 and wrongly to ground.
  7. Audioguru

    555 astable

    If the 555 IC is not connected "the right way around" then it is a cheap, defective or fake one from "over there". Buy genuine electronic parts from a real electronic parts distributor.
  8. Audioguru

    Portable Battery Charging Pod for E-Bike Trailer

    A guy used a computer fan to be the generator to light LEDs on his bicycle. It did not work until he used a HUGE fan that was difficult like dragging a fully open large umbrella around.
  9. Audioguru

    intermittent 555 monostable circuit help

    It is not odd that the long wire connected to the trigger pin 2 picks up interference since your circuit is missing an important pullup resistor.
  10. Audioguru

    intermittent 555 monostable circuit help

    It is important for a 555 to have a supply bypass capacitor as shown in its datasheet, and a supply and wiring that can produce the 400mA of "shoot-through" current produced by the old 555. The datasheet for a 555 shows that the trigger pin2 MUST have a pullup resistor. The tangle of wires all...
  11. Audioguru

    Problems while making a simple class A amplifier

    Without including the base current, I calculated simple voltages on yours and on mine. Then I simulated them:
  12. Audioguru

    Problems while making a simple class A amplifier

    You did not say the type of microphone. Most mics today are electret type that need to be powered. A dynamic mic has a coil and a magnet like a tiny loudspeaker. Your circuit has the transistor biased to be almost saturated and not amplifying. The 20k resistor should be about 3.3k. The 50 ohm...
  13. Audioguru

    Solar cell power

    Are your soar cells connected in series (wrong) or in parallel (correct)? Are the solar cells in bright sunlight (correct) or in the shade (wrong)?
  14. Audioguru

    static electricity generators

    Hey RAT, aren't you in Down Under that is summer time now? Here it is freezing in winter (almost Spring) and the humidity is very low so the static electricity doesn't drain away quickly.
  15. Audioguru

    I cant find where to buy spark gap "circuit interrupters"

    Spark gap oscillators and sequencing circuits were used 97 years ago. For the last 30 years we use transistors and ICs.
  16. Audioguru

    Hello, need a little help with this?

    In Canada each house has 240VAC center-tapped. Then there are two bands of 120V live and neutral or both lives producing 240VAC for high power like electric stoves, clothes dryers and air conditioners. Since he will have two times 1800W running all the time, the electricity bill will be VERY high.
  17. Audioguru

    Novel voltage doubler circuit need help plz

    Your sketch of a pcb shows the output shorted to the DC input. Then the shunt resistor is discharging the DC input. A resistor charging a capacitor then a spark gap discharging the capacitor is much too crude and an extremely old idea to be an oscillator today.
  18. Audioguru

    electric Bike

    I fly my RC airplanes lower when I hear and see a low flying rescue helicopter going to the nearby hospital. Kids fly huge kites much higher than real airplanes and helicopters.
  19. Audioguru

    electric Bike

    A big heavy lead-acid battery allows a bike to go very fast downhill. A current-limiting circuit will prevent an overloaded Lithium battery from catching on fire. My electric model airplanes (Li-PO battery) can climb at full power vertically (uphill) until they cannot be seen anymore and the...
  20. Audioguru

    Why is it PNP instead of PPN for transistors

    A speaker with an 8 ohms impedance usually has a 6 or 7 ohm resistance. The leads of your ohm-meter are probably the 1 ohms difference. Short the probes together to measure the resistance of the leads. Here is a graph of the impedance vs frequency of a speaker. The impedance is a peak at the...
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