>         Hi to all engineers.
>         last night I made a small circuitry to mute the analog line
>         the pic part works ok  but analog section didn't work at all.
>         on output when I add 10k pull up resister works fine but I can't
>         do that on audio line.
>         I connected pic with max4066 analog chip. the problem
>         I found is that 4066 needs voltage on output  to operate
>         which we do not have it my question is this is  there any part that
> can
>         be used to mute the analog line "audio" beside relay ?
>         any help will highly appreciated.
>
>         Andre

A simple method is to use a light dependent resistor in the audio
line. The LDR is very high resistance when dark, so a no power-mute
would have the LDR in line with the audio followed by a lowish
(2k-10k) resistor to ground. An LED driven by the PIC could enable/
disable it (2 Meg dark to around 5K light).
I have seen this system used but I have not used it personally, I
dont think there would be any significant distortion being a resistive
device but I don't know how linear an LDR is.
The circuit I saw actually used 2 LDRs in a "T" attenuator . That is
in line LDR, resistor to ground, in line LDR.

Hope this helps.


Lance Allen
Uni of Auckland
New Zealand