I just finished a remote receiver project where I had to de-emph using
an RC circuit. I have always heard that the rule of thumb is:
75 us for wide band broadcast audio and 750 us for narrow band. I used a
3.3k resistor and a 0.22uf cap. 726us - close enough. It sounded pretty
It sounded pretty
good, so I thought, what the heck, I'll sweep it (it was raining). Big
mistake. Now I don't understand why it sounds so good.Click here for
the plot:
http://webpages.charter.net/k4hal/de_emp.pdf
Not anywhere near 6db per octave. The impedance out of the discriminator
amp was pretty low, probably less than 100 ohms verified by loading it with
resistance and the impedance of the audio input was high - about 500k.
So, what is the correct time constant or corner freq for the circuit ?
Henry, K4HAL
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