Want to make a Rotary Switch Setup to test different caps.

[belwar]

Hi All,

I want to make a rig to test different capacitors.. I assume this can be done with a Rotory Switch.. Im going to butcher a guitar to put the setup in, so it doesnt have to be pretty. I want to test as many capacitors as possible at a time. So far I have at least 10 different caps.

Could someone help me locate a good switch for this purpose, and help explain how it should be wired?

Bel.

[tedmich]

check this
Auditioning Tone Capacitors - Premier Guitar

they just used alligator clips!

You would need a 2P10T rotary switch which are hard to find and BIG. Most rotary switches are 12 sections; 4p x 3T, 3p x 4T, 2p x 6T, 1p x 12T etc.

These would let you try 6 caps:
5,2 Pole 6 Position PANEL PCB Wiring ROTARY SWITCH 2P6T - eBay (item 300358816661 end time Oct-25-09 22:25:20 PDT)

if you have a Fender type cap connected to ground, you could use the 1P12T
5,One Pole 12 Position PANEL Wiring ROTARY SWITCH 1P12T - eBay (item 290361984693 end time Oct-27-09 20:21:30 PDT)

[belwar]

The exact number of caps to be tested isnt really important. There is a guy on E-bay with that 2P10T switch.

Do you have any idea how I would wire it?

That you very much for taking the time to answer my noob question

bel

[tedmich]

it depends how your guitar is wired; Gibsons have vol-cap-tone-ground,

while teles have vol-tone-cap-ground

on the Gibson you need to put the cap between the vol and tone pots so a 2P switch is needed I think.

On the Fender/Tele wiring you could just have a SP switch going to your caps with all of them already grounded on the ends. I think the article I linked goes into this.

Also see:
GuitarElectronics.com Guitar & Bass Guitar Wiring Diagrams & Repair Resources

for wiring diagrams

[Enzo]

Ever see a substitution box? They used to be pretty popular, but I don;t see them much anymore. They made them for caps, and also for resistors, some fancier than others. I am sure there were some inductor ones for someone at some time.

Imagine a little prject box with two clip wires coming out. They a rotary switch or a bunch of slide switches or whatever on the box. The switches slected a capacitance, and the two clip wires were used to connect it to a circuit.

A simple selector switch is simple. All you need is 1 pole 10 throws. Wire one end of all the caps together, and connect that to one clip wire. Now the switch. Using your rotary, there will be a common contact - the pole - and the individual switched contacts - the throws. Wire your second clip wire to the common switch pole terminal, then wire the free end of each cap to one of the throw terminals. That is it. Now wherever you want this cap in a circuit, clip it in place. the switch selects which one is in use.


usually we use them to select values, so a typical sub box might have switch positions for 100pf, 250pf, 470pf, .001uf, .0047uf, .01uf, .047uf, .1uf. You could chase down tonal bliss. but you could just as easily have five types of .022uf caps to select between. Up to you.

Here is a commercial kit for a basic one:
Capacitor Substitution Box

Here is a fancier one of the type called a decade box. The caps can be switched in and out in parallel, allowing you to make up any value you wanted. For example turning on a .1, a .01, and a .001 got you a .111 cap

Capacitance Decade Box | Tenma | 72-7265 (727265)

Oh, and how could I overlook this goldmine from Ted Weber's site:
https://amptechtools.powweb.com/subs.htm

[pontiacpete]

I have one of these:

Radio Attic's Archives - Eico 1140

got it on ebay for about $15.

does series and parallel with resistors

[Enzo]

Ooooh, I remember those. Very cool.

[belwar]

Originally Posted by Enzo

A simple selector switch is simple. All you need is 1 pole 10 throws. Wire one end of all the caps together, and connect that to one clip wire. Now the switch. Using your rotary, there will be a common contact - the pole - and the individual switched contacts - the throws. Wire your second clip wire to the common switch pole terminal, then wire the free end of each cap to one of the throw terminals. That is it. Now wherever you want this cap in a circuit, clip it in place. the switch selects which one is in use.

Thats a huge help, thank you.. The guitar is wired Gibson Style, so it sounds like I could easily wire in this Rotary Switch in between the Volume Pot and Ton Bot.. Treat the switch like the cap.

I know there are a hundred tests out there, and they all seem to be based around a les paul. I want to put it in my guitar, with my own pickups and see what sounds best to my ears. So i'll buy a bunch of caps and try with that! So that first switch listed (2P10T) would work?

bel

[Enzo]

There is no reason to hack up the guitar. You don't need to "install" a selector to try out different caps. Open the cover, either clip on or tack solder the two wires, and you can tape your selector to your strap until you find what you like, then solder that cap into place.

Answer this: with the stock tone control, how do you usually run it? If you usually run it fully bright, then it doesn't much matter what cap you use. At fully bright it is having essentially no effect.

[belwar]

Originally Posted by Enzo

There is no reason to hack up the guitar. You don't need to "install" a selector to try out different caps. Open the cover, either clip on or tack solder the two wires, and you can tape your selector to your strap until you find what you like, then solder that cap into place.

I'm a guitar maker, and have several seconds that I can't/dont want to sell. They make great test rigs. The guitar in question has cavities routed in the back of the guitar for quick humbucker replacement without de-stringing.

Originally Posted by Enzo

Answer this: with the stock tone control, how do you usually run it? If you usually run it fully bright, then it doesn't much matter what cap you use. At fully bright it is having essentially no effect.

It's not a matter of how *I* run it. Im a horrible guitar player. I want to create a rig to try multiple caps to determine what sounds best for this individual guitar. If I install it in the guitar, then I can swap pickups, and caps all within a few seconds.