I'm trying to tune the lights to the incoming music from my amplifier (yes I'm making a VU meter). My circuit is in grey and the output of the class AB push-pull amplifier (transistor emitters connected together) are connected to C3 and I noticed by changing any combination of any of the 5 components shown that the waveform can be modified. So I have a hunch I somehow have made a special active filter from 2. I think the first filter (from R13 and C3) is a high-pass filter and the second filter is a band-something filter.
I would use an electrolytic capacitor for C3 but I'm wondering if replacing it with a small ceramic capacitor and a high value resistor would be more beneficial (as opposed to low value resistor and a high value capacitor value) because there's been too many bad stories about electrolytics, one namely being accuracy loss with respect to temperature.
The yellow circuit came from http://www.talkingelectronics.com/projects/StereoVUmeter/StereoVU.html I know I didn't add a resistor in series with the input. I did get better results when I replaced the diode (in the talking electronics version) with a resistor because at all input audio volumes, the lights were following the sound more naturally whereas with the diode in place, if the sound volume is too low, then the lights would always stay on.
My LED stages are the same as whats in talking elecronics stereo VU meter except the diodes are 1N914 and transistors are 2N3904.
I would use an electrolytic capacitor for C3 but I'm wondering if replacing it with a small ceramic capacitor and a high value resistor would be more beneficial (as opposed to low value resistor and a high value capacitor value) because there's been too many bad stories about electrolytics, one namely being accuracy loss with respect to temperature.
The yellow circuit came from http://www.talkingelectronics.com/projects/StereoVUmeter/StereoVU.html I know I didn't add a resistor in series with the input. I did get better results when I replaced the diode (in the talking electronics version) with a resistor because at all input audio volumes, the lights were following the sound more naturally whereas with the diode in place, if the sound volume is too low, then the lights would always stay on.
My LED stages are the same as whats in talking elecronics stereo VU meter except the diodes are 1N914 and transistors are 2N3904.