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Topic: Help with LED VU Meter (Read 4 times) previous topic - next topic


It require cap at the input. Initially, I thought just to post a link:
(I like this drawings, post it all the time).

@ Magician

Thank for the link. I will use it.

@ wally_z

What audio source you are using ? ( sound card ? IPOD ? Mp3 ? Cassette player ? )

Does hZ in electricity matter for this kind of thing? (hZ or Hertz, is electricity flowing through a wire, at all times, not sure about AC, the electricity is off for 60 times a second and on for 60 times a second. I guess AC is a bit slower than that to consider it AC.)

I am assumming you are from North America ( USA ? Canada ? ) AC is Alternating Current  A sound signal is also AC. Just the frequency is different. ( about 20 Hz to 15 000 Hz ) Correct me if I am wrong


Is there anything I have to change in schematic #3? Also, if I use a resistor of different resistance, will it decrease performance?
Sorry for confusing, actually 10 k is "optimum" value for #2. Just read data sheet again for zener, and all looks cool with leakage current 10 uA.
You don't have to change anything, but if you do, please, be advised that higher value for resistor in series with diode will attenuate input signal in #3.


@Techone I am using my phone for audio output in mp3 format.

@Magician I realize now that AC has differing frequencies, and I guess DC is just 60Hz.


and I guess DC is just 60Hz.

Guess again. Or do some research.

AC is alternating current. The frequency that it alternates at is important.

DC is direct current. Its frequency is infinite.


DC is constant current, or frequency = 0.
AC is alternating current with any frequency, except 0.
Audio signal usually considered to be AC with frequencies between 20 Hz - 20 kHz

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