The weather today has been terrible; all overcast and rainy. Perfect Veteran’s Day weather -_- Since I couldn’t spend any time outside trying to chase down the oil drip on Bonnie, I decided to work on refreshing my python skilz (or lack thereof). As usual, the kids were being extra loud so I thought it would be a good idea to throw on my headphones to help block out some noise. That reminded me that I’ve been meaning to get around to finishing up a switch box project I came up with awhile ago but haven’t gotten around to working on yet. And so the plan’s changed, now instead of flipping bits, I’m busting out the soldering iron.

I tend to spend a lot of time at the computer, most of it with headphones on. I’m not necessarily trying to drown out the rest of my family, but when I have homework that has to get finished and the kids are screaming there isn’t much else that works. If I’m not working on homework though, I try to use my speakers so I at least feel less cut off from the rest of what’s going on in the house. Problem is, I don’t have one of those fancy store bought computer cases with a headphone jack (or USB ports for that matter) conveniently located on the front. All the hookups are ‘round back, and generally a pain to get to, so switching between headphones and speakers is more of an ordeal than you’d expect. The obvious solution would be to stuff my computer into a “real” case, but I don’t work that way. So I came up with the idea to build a little box that can switch between two inputs and two outputs, and has a volume control built in as well.

I ordered up the parts, contemplated the best layout for all the switches and audio jacks, and never bothered to start. My cheapy computer speakers (really just speaker thanks to the cord-loving cat) finally bit the dust so I was on headphones all the time and there was no need for the speaker switcherooer anymore. That changed last week when I picked up a half-way decent set of speakers again and it started to bug me every time I had to switch back and forth with the headphones. Fast forward to today and it’s finally time to finish the project I started almost two years ago.

I bought all the parts for this from Digi-Key, but I could have just as easily found all the parts at Jameco or another electronics supplier. The plan is to have two inputs that I can switch between (although I have no idea what the second input would be at this point), and two outputs that can be switched as well–headphones or speakers. The volume control was an afterthought, but I thought it might be nice to be able to control volume without having to use the mixer on the computer (I also don’t have one of those new fangled keyboards with volume controls built in–I don’t even have Windoze keys…).

Parts List

  Parts  

The first thing I did was lay out where all the parts would go to make sure there was enough room. This enclosure is big enough that it wasn’t much problem, and I decided to stack the two inputs on one side of the back, and the two outputs on the other. I used masking tape to protect the paint on the box, and my calipers to scribe layout lines (I penciled over the lines because they didn’t show up on camera, and I swear part of this picture was in focus).

  Layout  

In an attempt to keep the drill from wandering I used a punch to mark the holes, and then drilled a pilot hole followed up with a step-drill to get to the 1/4” holes needed for the audio jacks.

  Drilled  

I test fitted the audio jacks, and then moved on to the front where the process was the same for locating the two switches and the volume potentiometer.

  Back jacks  

Next, I loosely installed all the components to make sure I was happy with their location (not that I can do much about it at this point) before moving on to wiring.

  Test fitting components  

Everything looked good, so I pulled all the parts out and spent the next 15 minutes trying to figure out where I hid my wire strippers. I have a wonderful habit of putting things where “I’m sure to remember” next time I need to use them, and then forgetting where that place is. I’ve also been missing my side-cutters for at least a couple months, and lo and behold! They’re all in a box together with a couple spools of wire I started stocking up on in preparation to rewire Козел. It is a semi-logical place for the wire strippers, I just have a terrible memory. Anywho, let the wiring commence.

  Something’s missing…  

I gave the freshly wired parts a quick test with my phone and a pair of headphones, and everything seemed to work mostly as expected. The switches switched, and the volume control…controlled the volume, although not as well as I would have hoped. I had to turn the volume on the phone up pretty high to get a good range out of the switch box from plenty quiet to far too loud. I don’t think it’s really a huge deal, but I expected more control without having to turn the input up all the way.

Since everything works, I installed it in the box…

  Still missing…  

…and hooked it up to my computer only to find that one of the inputs sounds terrible, and one of the outputs is garbage. When my speakers are plugged in to it, they just buzz uncontrollably. Wonderful.

Turns out, I was terribly wrong when I thought that I could get away without grounding anything. The switches only ground through the front panel, but the audio jacks have a ground pin. I went back and added ground wires between all four jacks and tried again. Voila! The sound is great now through both inputs and both outputs, although the volume control does almost nothing with my speakers. It does however do a good job of controlling the volume of my headphones, so I suspect it has something to do with the speakers being active instead of passive like the headphones.

This project didn’t take too long to finish once I actually got started, but it’s been a long time in the making. I looked up the invoice from ordering the parts from Digi-Key, and it’s dated January of 2019. It’s been nearly two years, but I’m glad it’s finally done. I think it turned out pretty well, and now I can crank it all the way up to 11.

  Veteran’s Day Switcheroo  

Happy Veteran’s Day.