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  1. Audioguru

    110v strobe flasher circuit help

    The flashing light is dangerous because it causes some people to have a epileptic seizure.
  2. Audioguru

    I need some experienced peoples advice

    You need a diesel generator designed to power a building, not a car.
  3. Audioguru

    I need some experienced peoples advice

    Kiss your hearing "goodbye". Here is a 22" subwoofer rated for 4000W at 2 ohms. It needs a few people to lift it. The peak power is 8000W then the power amp/voltage stepup circuit must be powered from more than 555A at 14.4V.
  4. Audioguru

    How to charge a lithium battery for a DIY bluetooth speaker

    Correction. There is a Boom Box in another thread that uses a fairly large 3.7V Lithium battery that has its voltage boosted so that the amplifier output is a true 12.5W into each 4 ohms speaker.
  5. Audioguru

    How to charge a lithium battery for a DIY bluetooth speaker

    If you are buying the Amazon receiver then it comes with two receivers but you need only one receiver. Sell the extra receiver. Amazon is mistaken, the receiver does not have a power amplifier for speakers, instead it has low power outputs for headphones or it can feed an external power...
  6. Audioguru

    555 Trigger

    When the supply is 3.0V and there is no audio input signal, do you measure 1.2V or 1.3V at the base of the darlington? Do you measure 2.0VDC at the collector? When the output of the preamp is a spike, what is the input signal?
  7. Audioguru

    555 Trigger

    An old fashioned condenser mic uses an external 48V power supply to bias its fixed and audio-moving variable capacitor diaphragms. A newer electret-condenser mic has the 48V permanently charged in its electret material. The electret mic has a Jfet in it to convert the extremely high impedance of...
  8. Audioguru

    555 Trigger

    Peter, you do not have a condenser mic that needs to be biased with 48V. Instead you have an electret mic that has 48V permanently charged in its electret material. Most electret mics draw 300uA to 500uA and need at least 2V across it. Then your 10k resistor powering it has a resistance too high...
  9. Audioguru

    555 Trigger

    The schematic recently posted: 1) No VCC voltage. 2) Mics in parallel load down their output levels. 3) The 1k emitter resistor on the no-part-number transistor reduces its voltage gain to be about 200 times too low. The 555 in my simulation is not triggered when the input level is loud.
  10. Audioguru

    555 Trigger

    The sellers at Fleabay use very poor translation. A passive piezo is a transducer but one that is powered from DC has an oscillator in it and its frequency listed. Some of the ebay ones have both passive and DC listed.
  11. Audioguru

    555 Trigger

    The simple cheap Sound Detector Module was designed to use one electret microphone. It does not have a piezo disc and is not designed to drive one. The output of the module can be used to drive a piezo beeper that already has an oscillator in it.
  12. Audioguru

    Connecting a 8 ohm buzzer with a 555 timer

    The original circuit shows photos of a piezo transducer, not a speaker and not a piezo beeper that has an oscillator in it..
  13. Audioguru

    Connecting a 8 ohm buzzer with a 555 timer

    The circuit has capacitor C4 in series with the speaker to avoid the speaker having DC in it. Without the capacitor, the 555 output tries to go from almost 0V to almost 10V which tries to produce a current of 10V/8 ohms= 1250mA which is way too high for a 200mA 555. With the capacitor, the...
  14. Audioguru

    Connecting a 8 ohm buzzer with a 555 timer

    Simply do the math. A 555 will be overloaded when powered with 9V and is feeding an 8 ohm speaker. Also, the rest of the circuit might not work with only 9V.
  15. Audioguru

    Connecting a 8 ohm buzzer with a 555 timer

    A pcb is a Printed Circuit board with the parts soldered on to it. The maximum allowed output current for a 555 is 200mA. The circuit with a 12V supply feeds 5V pulses to the 8 ohms speaker. 5V/8 ohms= 625mA that burns out the 555. I said how to fix it in your other forum about it.
  16. Audioguru

    Help with building a pre amp for my selfbuild Microphone

    You need to buy a mic and a preamp that is matched to it.
  17. Audioguru

    Connecting a 8 ohm buzzer with a 555 timer

    Get rid of the tangled mess of wires all over the place and instead use a neat and tidy pcb. The buzzer is probably an 8 ohm speaker that will quickly burn out the 555 oscillator.
  18. Audioguru

    555 Trigger

    The datasheet of the Sound Impact Sensor says its output is active high. It already has a 555 timer on it. Increase the 4.7k resistor to about 470k then after a noise triggers it, in 5 seconds its output will go low .
  19. Audioguru

    Help with building a pre amp for my selfbuild Microphone

    Anybody can post a video of a circuit on You Tube then many of the video circuits have serious design errors. Of course the added Jfet needed a gate resistor to ground. The circuit will not work because it is completely wrong for both mic cartridges shown: 1) The 100S cartridge shown in the...
  20. Audioguru

    I need a sensitive audio trigger for a 555.

    Any sound such as a dog barking, a motorcycle, airplane or noisy car, the TV or radio, a door bell, telephone ringing, people talking etc. The circuit that was copied was to detect loud hand claps, not just the faint brushes on the microphone.
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