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  1. Audioguru

    I need a sensitive audio trigger for a 555.

    The microphone is not a condensor type, instead it must be an electret type. A translation problem from the distant country. The microphone's shield is its wrong output that will pickup lots of interference. The positive wire of an electret mic is its shielded output. The school kid in...
  2. Audioguru

    Need help with FM transmitter "adaptation" in photo

    Near my home there is a huge river with a long bridge over it for cars. A student at the nearby university was driving his Ferrari sports car over the bridge as fast as it could go. At the end of the bridge the car "flew" into a light pole and burned to almost nothing. The news said little...
  3. Audioguru

    Need help with FM transmitter "adaptation" in photo

    If you do not live in civilization then you can do anything you want. We are civilized people on this forum.
  4. Audioguru

    Need help with FM transmitter "adaptation" in photo

    Do people modify their car so it can fly like a jet airplane? Is the cheap FM transmitter made with enough power to have a range that exceeds the short distance from your phone inside the car to the car radio so that it is legal? We are not allowed to show illegal circuits on this forum.
  5. Audioguru

    Need help with FM transmitter "adaptation" in photo

    The FM transmitter in the video is completely different to the one sold by AliExpress.
  6. Audioguru

    Need help with FM transmitter "adaptation" in photo

    The Micromitter was an article in Australia's Silicon Chip magazine and a kit was made for it 16 years ago. It used a Rohm transmitter IC and had an attenuator on its antenna output so that its 20m range was legal. The IC had 14 FM radio frequencies programmed into it and used a crystal for good...
  7. Audioguru

    Changing microphone in to Line level in??

    The AliExpress explanation of the board is terrible! I think the board you have produces audio reverberation. They say its input can be another board which is a microphone preamp. Then the input level to the reverberation board is line level. AliExpress also seems to say that the reverberation...
  8. Audioguru

    Need help with FM transmitter "adaptation" in photo

    Bypassing the resistor will short the output signal to ground. I think he said that he "soldered in a wire to bypass it" but instead he wrongly connected his new antenna wire to GND which is Ground. He should have connected his new antenna wire the the ANT end of the resistor. Don't cause...
  9. Audioguru

    Need help with FM transmitter "adaptation" in photo

    The Englishman "woked" very far away so the modification made the output level be much higher and be very illegal. Of course, the video might be a fake so maybe not. The range might be "fauthah ovah wotah" Sorry for the severe English accent..
  10. Audioguru

    Need help with FM transmitter "adaptation" in photo

    You need a certified circuit, a license from your government and an allowed radio frequency to be a radio station so that you do not cause interference with other communications and other radio stations. Therefore the circuit you have has a short range to prevent the interference problems.
  11. Audioguru

    Have a discontinued gadget, need Lithium Polymer battery

    I did not look through the entire list of batteries but the local hobby store near me sells at least two 200mAh Li-PO batteries for $6.99 Canadian. They might be less than $5.00 in the USA. I do not know the sizes.
  12. Audioguru

    Have a discontinued gadget, need Lithium Polymer battery

    You do not know if the complex charging circuit is separate, in the battery or in the product. It is complex to prevent the battery from exploding or causing a fire. You also do not know if the battery or product has a complex "protection circuit" to sense low voltage and disconnect the battery...
  13. Audioguru

    Tuning TV sound bar

    I got my hearing tested when I was 70 years old and was told that my high frequencies range was very bad and was normal for my age. So I tried a 3 months demo and was satisfied that new hearing aids made my hearing better than when I was young. The hearing aids boost high audio frequencies but...
  14. Audioguru

    LM3886 amp build

    I hope it is not built on a solderless breadboard with a huge tangle of wires all over the place!
  15. Audioguru

    Fixing a Li-ion battery pack for a laptop

    In your post #26 you said a new battery is 14.8V which is much too high for three Li-Ion cells. 14.8V/3.7V= 4 (four cells) Your photo shows 10.95V (3 cells of 3.65V), 12.6V (3 fully charged cells of 4.2V) and 19.5V (used by very old laptops).
  16. Audioguru

    Fixing a Li-ion battery pack for a laptop

    An older style lithium 18650 battery cell is 4.2V when fully charged, 3.2V when the voltage is low and its load should be disconnected then 3.7V is when it is half discharged. Three cells produce 12.6V when fully charged. If a cell is charged to a voltage higher than 4.2V then there is a risk...
  17. Audioguru

    Question reform electrolytic capacitor

    This repeating thread is locked on the other forum.
  18. Audioguru

    LM3886 amp build

    The schematic in the video has a signal ground for the input but also has a power ground. It wrongly does not show them connected together.
  19. Audioguru

    LM3886 amp build

    Maybe you bought a fake LM3886 from ebay?
  20. Audioguru

    Hear like a dog - electronic ear protection modification

    I noticed that the article did not include a recording of the lousy old LM324 quad opamp producing only low frequency noise. Google has many videos that play bat sounds at frequencies that we can hear. The sounds are just noises.
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