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I had some problems zeroing in on some resistance and capacitance values building a tube-distortion stompbox. Inspired by Matt-the-Modulator's work ( http://www.flickr.com/photos/matt_the_modulator/3874753521/in/pool-make/ ), I created a simple interface to swiftly switch values of one or both.

Please bear the lack of step-by-step pictures. I didn't plan an instructable.

Step 1: Choose Resistance and Capacitance Values You Want.

I chose to use a dipole, 6-way switch for each component type. Thus, 12 resistors and 12 capacitors are available for use.

Being geared towards music, I chose resistors from packs of carbon composite resistors purchased on ebay. These were 1/2W capable.

For capacitors, one pole was filled with 6 non-polarized values. The other pole had 2 tantalum and 4 standard polarized values.

Since some schematics call for sound-altering diodes, I added a standard (1N4001-1N4007) type,a small switching type, and an LED to one side.

Step 2: Get Parts.


I pulled the 3 component types and a Radio Shack PCB from my stockpile-o-stuff. Next, I purchased the 2 switches and a 4"x2"x2" black plastic box from Radio Shack, as well as a small euro-style barrier junction strip.

Step 3: Plan the Layout.


Using pre-formatted PCBs takes some planning. I used an almost-breadboard style that worked beautifully.

Step 4: Put It Together.


Put it together. I had some large capacitors, so creative placement was needed. Just trying to save a buck by using stocks on hand.

Please ignore the polarization scribbles. Plans change when components hit the board.

They aren't visible, but I scraped the copper from the center of the 2 input  busses to create 4 instead.

Step 5: Wire It Up.

Know your switches' positions. Use enough length for mounting, but too much can create a headache (and stray capacitance!).

Step 6: Drill Holes.


Inputs, outputs, and 2 switches. Don't forget screwholes for barrier strips! That made 15 holes for me.

Step 7: Mounting and Testing.


Mount your hardware. Insert inputs and outputs. Test your work with a multimeter. Got it in one! Made me feel good!

It turned out I didn't need to mount the board. It just worked out.

Don't forget to label!

With this setup, I can not just switch between one or another value, I can serial or parallel the in/outs for other resistance and RC values. If you don't mix polarizations in your design, that can be done with capacitance. I imagine strange results if I mix that on mine, though.

When you get the sound (or other result) you desire, plug them into your finished project.
Guitar, etc FX pedals/stompboxes. It's a great way to tweak your sounds and gain before construction. It beats the crap out of switching components in a breadboard! Faster and easier to wire in the box and switch the knob. I don't get to use it much- no free time lately. But it simplified the creative process. It could be used the same way in many projects. Just tailor the component ranges for your expected needs. Some pots with an ohmmeter connected would be more suitable for precision needs, but ranges are enough for my work. Thanks for commenting!
Not a bad thing to have on hand. What are you going to use it for?

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