Solid state switching of signals

What would be the cleanest way to switch an AC signal path on and off using solid state?

The signal is only low, a few volts, and since it's a signal I can't really make do with diode voltage drops, which immediately points towards bias / trigger devices where the only drop is from their internal resistance.

I'd prefer not to have to use solid state relays since they're kind of expensive and I need lots of them, nore do I absolutely need their isolation potential.
 
For low power signal I (and many others) use this way (T14 and T15 in the attached circuit) ;)

There are other ways, but this is nice and clean :D

- By the way.... This is from the QUAD 34 preamp
 

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mzzj

Member
2005-07-02 8:17 pm
65N 25E
eeka chu said:
What would be the cleanest way to switch an AC signal path on and off using solid state?

The signal is only low, a few volts, and since it's a signal I can't really make do with diode voltage drops, which immediately points towards bias / trigger devices where the only drop is from their internal resistance.

I'd prefer not to have to use solid state relays since they're kind of expensive and I need lots of them, nore do I absolutely need their isolation potential.


HC4066 and similar cmos swiches are classically used for things like these. VHC4066 is tad better in on-resistance and maxim-ic for example has improved versions that are still pin compatible with 4066. 4066 on-resistance is variable and varying with signal strengt, somewhere between 50-500ohms so your input impedance after switch has to be enough high.
 
For low-current signals, try this way:
[IMGHTTPDEAD]http://img46.imageshack.us/img46/2194/selector7gt.jpg[/IMGHTTPDEAD]
No signal distortion introduced.
Switches W1-W3 - any bidirectional type: solid state, relay contacts, etc.
Control: only one switch open at a time.
Need to high-impedance load, or opamp input.

Cheers.