Making a Channel Switcher

S

Seafroggys

Well-known member
I have made a basic splitter before, taking a single 1/4" input into two simultaneous 1/4" outputs that works well. Now I want to make one where I can switch between single outputs. At band rehearsal yesterday, my keyboardist decided to start using more organ, and we ran it through one of my amps to give it grit, but she still wants to switch to piano and run that through the PA. It would be easy if it was just a switch rather than re-patching cables.

What would I need to achieve this?
 
What is it...a single unbalanced 1/4" jack that you want to send to either A or B?

For any DIY switching application, all you really need is a suitable box, the right number of jack sockets, and a switch with enough poles and throws.

Poles = number of separate conductors, and throws means number of discreet destinations per pole.
Single pole double throw (1pdt) takes one conductor and sends it to A or B.
Double pole double throw (dpdt) takes two conductors and sends them to A or B. See?

Assuming you want to switch shield too, a dpdt would cover you for one 1/4" unbalanced output.
 
If you use a SPDT ON-ON switch, you use one switch that swaps the hot. Just wire the ground straight through (or try to find a DPDT)...every time you press the switch it goes to the other output.
 
BroKen_H said:
If you use a SPDT ON-ON switch, you use one switch that swaps the hot. Just wire the ground straight through (or try to find a DPDT)...every time you press the switch it goes to the other output.
Click to expand...

Good call.
I tie all the grounds together with things like that, but I wasn't sure if it was a good thing to recommend.
Nice one. :)
 
BroKen_H said:
If you use a SPDT ON-ON switch, you use one switch that swaps the hot. Just wire the ground straight through (or try to find a DPDT)...every time you press the switch it goes to the other output.
Click to expand...

I'd use a SPDT in a metal BUD box and ground the box to maintain the shield throughout.
 
I would use a DPDT switch and switch the earth lines as well.

Note that only the input jack earth is connected to the case and therefore only one output at a time is earthed to the input. This is to prevent a hum loop which can occur when gear is earthed "twice". Once to mains earth and secondly via a signal lead to another bit of kit.
Note also that the jacks should be plastic body types to insulate them from case.

If you want to get seriously cute you can use a 3 pole DT switch (or 4 pole) and have LED indicators. One of the jacks will then need to be stereo to give a "no use, no power" switch. A 3V button Lithium would last ages.

If you used 3amp switches this could easily switch 100watts of 8Ohm speakers as well.

Dave.
 

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10$ for a DPDT switch. Geez
You can buy 3PDT from China for less than2$
Enclosure seems like nice price though.
It might be an idea to use some sort of low z buffer. Just thinking it might end up popping when switched.
I'm still learning so correct me if i'm wrong.
 
kip4 said:
10$ for a DPDT switch. Geez
You can buy 3PDT from China for less than2$
Enclosure seems like nice price though.
It might be an idea to use some sort of low z buffer. Just thinking it might end up popping when switched.
I'm still learning so correct me if i'm wrong.
Click to expand...

DO NOT cheap out on switches! They get a very hard life and whilst most components can be bought very cheaply these days with confidence, switches are not one of them.

Should not pop switching line level signals. If it does it will be because there is some residual DC on an out put or input due to bad design. Check for this with a Digital Multi Meter...Don't have a DMM? ....Don't start electronics projects without one!

Dave.
 
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