Some problems about the audio amplifier circuit

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milkii
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Re: Some problems about the audio amplifier circuit

Post by milkii »

There's ##music-electronics on libera.chat.

I thought capacitors limited signals closer to DC, i.e. low frequencies, but I'm often wrong in life!

This seems like a good video on the topic, I'll watch it fully soon https://youtu.be/l-u8J-yh9ZA

they/them ta / libreav.org / wiki.thingsandstuff.org/Audio and related pages / gh

merlyn
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Re: Some problems about the audio amplifier circuit

Post by merlyn »

One way of thinking about a capacitor is as a frequency dependent resistor. When dealing with AC instead of 'resistance' we say 'impedance'. At low frequencies a capacitor has a high impedance, and at high frequencies it has a low impedance.

DC is the lowest frequency, it's 0Hz, so at DC a capacitor looks like an open circuit. This is why there is often a capacitor on an audio input -- to block DC. 'DC coupled' inputs leave out the capacitor and these are important when using low frequency control signals.

At high frequencies a capacitor looks like a short circuit and this is why you see loads of capacitors on a motherboard. They connect the power supply rail to earth so that voltage spikes (high frequency) go to earth.
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