Ok, I have a selection of components and want to make an analogue switch that will turn on or off line level audio.
The circuit needs to work and have the minimum of components. Input and output is line level audio, enable is 5V active high.
Devices available
J310 N channel JFET
2N7000 MOSFET
Standard NPN BJT eg 2sc1815 or bc547.
Help!
Okay, I'm sticking my neck out here because you probably know more about this stuff than I do but I think that for audio frequencies, the JFET or MOSFET might be overkill.
All the world’s a stage, but obviously the play is unrehearsed and everybody is ad-libbing his lines. Maybe that’s why it’s hard to tell if we’re living in a tragedy or a farce.
Doesn't matter, all that matters is its the simplest circuit with as few components as possible.Originally Posted by KJ6BSO
Tried a jfet, switched on via a 4.7k resistor. Almost worked, but was distorted. Perhaps a small amount of positive bias will work properly?
ANALOG DEVICES ADGxxx series of ICs or INTERSIL DG411-413 are analogue switches. I'm using these already so I suggest trying these, you don't need any extra components.
Ok I think I've done it with a JFET.
Three resistors, 1 jfet.
22k pulldown resistors to Gnd from Drain and Source.
100k gate discharge resistor from Gate to Gnd.
Audio in to Drain.
Audio out from Source.
5V on signal directly to Gate.
You can twist two wires together to turn on and undo them to turn off. That's zero components.
If it's a war on drugs, then free the POW's.
If you used a bipolar transistor, couldn't you do it with just two resistors?
All the world’s a stage, but obviously the play is unrehearsed and everybody is ad-libbing his lines. Maybe that’s why it’s hard to tell if we’re living in a tragedy or a farce.
CD4066 CMOS switch. 4 channels; 60dB minimum isolation between input/output lines and adjacent channels. One 14-pin DIP.
"Everyone wants to be an AM Gangsta until it's time to start doing AM Gangsta shit."
Untested, but should do the trick....
5 Volt switch input will cause the MOSFET to fully conduct, dropping Line Out to ground. Audio voltage is now dropped across R2. R1 keeps the MOSFET inactive when not connected to voltage source, and may be omitted.
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