[sdiy] God! Do I need a simple latch switch!

[Neil Johnson]

> ... a push button, simple, electronic, latch switch that will perform
> 1: spdt and 2 dpdt!

Suggestions:
1) one of the DG series analogue switches
2) relay (seriously, mercury-wetted miniature relays, great for audio)
3) FETs (discrete version of #1)
4) diodes (again, discrete, like #1 - maybe cheaper?)
5) lots (6?) of cadmium-sulphide cells and lamps/LEDs

You haven't specified which direction the audio(?) is going, so the above
options will/should work for both ways.  If you could narrow-down the spec
I'm sure many more ideas will be forthcoming.

E.g. UNTRIED IDEA: taking the SPDT with single-source and two
destinations, can use a couple of diodes, four resistors and a couple of
caps to implement the switch - in each leg you have R-D(a)-R-C then apply
negative bias to diode cathode to turn off that leg of the switch (or
replace the diode with a transistor to isolate the control signal from the
audio path).  Though you'll probably get thumps from switching, so ramp
the bias up and down slowly.  This works on the idea that the audio is a
few volts wibbling around zero, so bringing the diode cathode down to,
say, -15V will take away any audio along that path.  Probably not so
useful if you're switching mains though - far too many amps to handle
safely with a 1N4148.

Tea break over - back to work!

Neil

--
Neil Johnson :: Computer Laboratory :: University of Cambridge ::
  http://www.cl.cam.ac.uk/~nej22           +44 (0) 1223 334 477