Build a resistor sub box

Build a resistor sub box

Here’s a tool that’s super easy to build and super useful. I call it the Bend Finder because I use it to help me find interesting glitched and bends in circuits, but really it’s just a resistor sub box and it’s got tons of uses other than in circuit bending. Most pro sub boxes use rotary switches to switch between set values of resistance and most pro sub boxes are expensive! For the kind of work I’m doing, I prefer using pots rather than rotary switches which works for me since using pots is a quicker, easier and cheaper option.


You want at least 3 or 4 values of potentiometer. I use 1k, 10k, 100k and 1M. You can do smaller increments if you want and include some 5’s in there. A switch is pretty useful and then I have it all connect using two binding posts. These are good cause you can attach just about anything to them. You can use any connection terminal you want. I’ve used bolts before and those work fine. There are lots of ways you can trick out your sub box.

  • One thing I’m going to add to mine is a set of tip jacks that are wired to the connection terminals. Tip jacks are the size of standard multi meter probes. This will allow me to easily plug my meter into my box to get an accurate reading of the pots.
  • I suggest adding a 1k or 100ohm 10 turn pot. This is great for making subtle adjustments.
  • You can add a pushbutton in parallel with the on/off switch. This will allow you to make momentary connections.
  • Make some banana plugs with alligator clips on the end. You can plug these into the binding posts for easy connection of test leads.
  • Add more pots and switches.

8 thoughts on “Build a resistor sub box

  1. ROB K636 says:

    I have seen them as low as $150. This one is nice and cheap for electronic tinkering.

  2. pim says:

    what is the meter on the bottom of your very nice gear ? Is it a steampunk ohm meter ?

    1. Jonny D. Narya says:

      That’s a counter knob that reports now much the 10 turn is set. I haven’t seen one that looks as nice as that one before personally and really have to find some!

      1. casperelectronics says:

        right.. it’s just a 10 turn 1K pot with a revolving digital read out that tells you what the setting is. They have one at mouser but it only comes as a 10K. Here’s the part # 652-3610S-1-103. oh yeah, and it’s 80 freakin dollars!
        I found 4 of these (1k models) in a piece of test equipment that was being thrown away.

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