Hack a guitar tuner for pedal-board use
Having a tuner pedal is really useful. It means you don’t have to unplug anything to tune, and it doubles as a mute. They can be bought pretty cheaply, but where would the fun in that be? I decided to hack an old tuner I had lying around:
When I bought my electric guitar on eBay, it came with this tuner. I already have a smaller tuner, and so I came up with this little idea for turning it into a pedal tuner. While it has an output and can thus be used in a chain to the amp, it adds a nasty little buzz, so that’s not a very good option.
On the top right corner you can see where I added a 9V DC jack. This allows me to leave the tuner on and not worry about draining a battery. I just plug it into the multi power supply brick with the rest of my pedals. To add this, I simply drilled a hole (the plastic broke, so I glued it back together), snipped the battery clip wires and wired the jack in. Because the tuner has a plastic enclosure, an un-isolated jack is ok to use.
The next step is to build a mini A/B channel footswitch:
This is a pretty simple little switch to make. I decided to wire in a two-colour LED which is either red or green depending on which output is active. You should be able to get the parts from most electronics shops, otherwise online. The parts needed are:
- Enclosure (I used a die-cast aluminium ‘Hammond type A’ box, but you can always use a larger one)
- 3PDT footswitch (3 pole double-throw – I got a couple cheaper on ebay)
- 1 x 6.3mm Stereo jack
- 2 x 6.3mm Mono jack
- Isolated 9V DC jack
- wire & solder
- dual-colour LED & bezel mount
- 1k resistor
When buying 9V DC jacks, just be aware that there are two different size pins. I found this out the hard way, as I managed to buy the jacks with a larger internal pin. The cables I had needed the smaller one, so I solved this by soldering my own daisy chain cable with the appropriate plugs in each end.
Be sure to measure (twice – double check everything will fit.. it’s tight) and drill the enclosure before you paint it. I use Molotow spray cans, which I can get for a couple of euros at the local art shop. They are easy to use and dry quickly. I also recommend lining the inside of the enclosure with electrical tape just to make sure nothing shorts out on the box.
Note that unlike a normal LED, the longer wire is negative.
Once it’s all wired in, simply plug the tuner into the red out put and the green output to the rest of your effects chain / amp and plug in the 9V cables and you’re good to go. Here’s how it works: