Question on using 1 switch to control multiple switches

ricoloverde · Joined: Nov 09, 2009 Posts: 39 Location: berkeley

How can I use a single spst switch to control multiple switches?
I need to turn 18 things off and on with one switch. Can I do it with transistors, or is there an Ic out there that would be better?

Thank you so much for any help offered.

DrJustice · Posted: Wed May 26, 2010 6:27 pm Post subject:

It depends on what kind of signals you need to switch.

A single switch can control 18 transistors if the signals are unipolar, or 18 pairs of transistors or 18 CMOS switches (e.g. CD4066) if the signals are bipolar. You could control 18 relays, or you could use an extreme mechanical switch (e.g. stacked rotary) if the power requirements are large.

DJ
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ricoloverde · Joined: Nov 09, 2009 Posts: 39 Location: berkeley

thank you so much for your help.

not too sure what you mean by bipolar / unipolar. I have a tr-808 and i want it so when the switch is closed 18 resistors are added to the 808 circuit. when its open they are taken out. basically ive modded an 808 an want to be able to bypass the mods so it can play in its original state

rico

Inventor · Posted: Thu May 27, 2010 12:24 am Post subject:

Tell us a little more about how these resistors are added to the circuit. Are they series or shunt, input or output, etc. Then we can be more specific regarding your application.

Les

DrJustice

ricoloverde · Joined: Nov 09, 2009 Posts: 39 Location: berkeley

@DrJustice Thank you so much for your help. Appreciate it a lot.

Were doing the mods for the 808 from:
http://xlargex.xl.funpic.de/

under TR-808 clone modifications.

I have put all the mods into a breakout box and the box is unattached the 808 but will not function in its normal state as several resistors were removed for the mod. I would like to be able to have a switch on the 808 which would put the original resistors back into the circuit.

i.e for bass drum tune I took the 47k out for the mod, but would like to be able to put it back into the circuit for a "normal" state. Rather than having 18 bypass switches I was hoping to have a master switch. I hope this makes sense.

AGAIN THANK YOU FOR YOUR TIME.

DrJustice · Posted: Thu May 27, 2010 5:08 pm Post subject:

OK, I've had a quick look at some of the schematics and some of the mods. Since there is a mixture of AC and DC signals and the 808 uses a PSU of +/- 15V, I would make short work of it and go for relays. Then I would know that it all works fine. Some money could be saved by using CMOS switches in some places, but I wouldn't bother unless the budget was extremely critical. Relays are simple to understand and easy to get to work, and the ones we're talking about here are tiny; 9 of them could possibly be placed in your breakout box.

DJ
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Edit: Typos

Inventor · Posted: Thu May 27, 2010 6:40 pm Post subject:

I agree with DJ. As a circuit designer I'd probably use CMOS switches myself, but that would take more of an effort in understanding what's going on in the circuit. Relays are easier to work with as DJ says. Plus they go "click" when you switch them! Laughing

Les

p.s. did you know that the first computer bug was actually a moth that got stuck in an early computer's relay?