A/B Switch on the Cheap





Introduction: A/B Switch on the Cheap

Rather than buying something from the store, I often just choose to make my own. I made this A/B switch because the drivers for my front ports aren't allowing me to record through Audacity properly on my machine. Now this has been done before but I still like to put it up.

What you will need:
A box of some sort to put the components into (I made my own custom, but any small box will do)
Glue of choice (I used two, super glue and epoxy)
A/B switch
Two 3.5mm headphone jacks
Soldering Iron and solder
A length of cable with one intact 3.5mm headphone jack (or build a cable [here]https://www.instructables.com/id/TRS_headphone_plug_rebuild/)

Step 1: Build the Circuit

First thing you will want to do is build the circuit and test it. I discovered some problems with mine. Make sure the polarities are right. Then your going to want to un-solder the the main cable from the circuit so you can fit it through the hole in the box.

Step 2: Add Componets to the Box and Wire

At this point you'll want to glue in the switch and jacks and run the audio cable in through holes you've made. So you should have 4 of them (one should be square for the switch). Once you've glued them in go ahead and solder it all back together.

Step 3: Close Up Shop

As an addition I added a magnet to the back so I could stick it to the side of my case, then glued it shut. A good idea also would be to test the strength of the magnets before gluing it shut. Mine won't attach to the side of the computer like I had hoped but sits on top and won't move easily which is good.

Step 4: Your Finished

Your A/B switch is now complete, plug it in and test it. Happy switching!

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13 Discussions

Actaully the amount of magnetism required to damage a hd is quite a bit... Altho I wouldnt recomend mounting a HD with a magnet.. Refridgerator magnets and even most toy magnets are no were near as powerful as the rare earth actuator magnets that are inside the hard drive..

Unless you can use the magnet to pickup the computer I wouldnt worry about the magnetism of the magnet...

I large speaker magnet would be bad however but most (older) cases have a pc speaker inside that will easily attract screws and the like from about 1 inch or more..

Just my $.02 from working on computer for over 15 years...

It sits on top and is just strong enough to keep it from sliding around. Doesn't affect anything inside the PC. The DVD drive which is really close to it doesn't seem affected after many burns. Just don't use a super strong magnet and you'll be fine, or some Velcro.

HDD drives are shielded from magnetic emissions. it's the floppy drives that might be affected, although not much people still use floppy drives (i do).

Almost everything came from my random parts box in my closet. The jack from a dead set of headphones, the cable from a computer (cdrom audio cable), you get the idea. I think only the heat shrink came from Radio Shack. The box/case I made from scratch, a couple pieces of clear plastic from zip disk cases, a dremil, some epoxy, and then painted. Hope this helps.

thanks, I plan on building this because as it turns out using a y-cable to share a set of speakers among two PCs isn't so hot.

Yeah, I can imagine the noise when you disconnect the desktop speakers. If I were to do this a second time around i'd skip building the box from scratch and use something easy, like an Altoids tin (I had planned on using an external phone jack but it broke half way though fabrication). Something that comes apart or opens is always good, that and it's quicker to fix. Let me know how it works out.

I need something like this for my video capture card. The card uses the line in to record sound. I also use the line in to record sound from the speakers.

I don't know much about magnets and computers, but I know that you don't want them to be in close to each other. I'd advise against using a magnetic attachment method, if you are attaching to the side of a computer case. Nicely executed project however, looks good, and is simple. Will also save plugs from wear and tear, being pulled out constantly.

I understand what you are doing... almost... What is the purpose of this "a/b switch"? Is it for switching between a headset and desktop speakers?

1 reply

great build - I have a commercial one and the switch is going wonky on it. Makes funny noise. Neat and tidy, I like it.