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DIY Stompboxes => Building your own stompbox => Topic started by: poppyman on July 19, 2012, 02:08:17 PM

Title: input cap switch: 3 different values.
Post by: poppyman on July 19, 2012, 02:08:17 PM
Hello,

just a noob question about input cap switch mods in fuzzes or OD.
I actually found myself more successful with this than with tone pot mods. A plain switch between the stock cap and something bigger to add bass frequencies.

I usually do as explained by Beavis audio on his (very clear and awesome) website, in the "switch" section. I was wondering how to make a switch with 3 different input caps.
What you be the wiring diagram?
I guess I'll have to use an on/off/on switch and wire the smallest cap in series so I can "add" the other ones alternatively...Would this wiring work ?: (wiring inspired by Beavis)


(http://img228.imageshack.us/img228/7192/inputcaptswitch.jpg) (http://imageshack.us/photo/my-images/228/inputcaptswitch.jpg/)

Uploaded with ImageShack.us (http://imageshack.us)


Could someone give me a hint on this?

Thank in avance.  ;)
Title: Re: input cap switch: 3 different values.
Post by: midwayfair on July 19, 2012, 02:18:52 PM
Yup, that works, but it can be done simpler.

Here's one way if you've already got a cap soldered to the board: Use a SPDT on/off/on. You wire cap 1 to the board this one's always on. Then you wire one lead of cap 2 to north pole of the switch; one lead of cap 3 to the south pole; and the other leads of both caps to one side of C1. Then you run a wire from the center (common) pole of your SPDT to the other side of the C1 input cap. In the center position, only the stock cap is active. Thrown one way, cap 2 will be connected across C1, adding its value to the capacitance. Thrown the other way, C3 adds its value.

But wait, there's an even easier way to do it. Use an on/on/on SPDT. Put the smallest value you want on one side of the switch, the middle value on the other side of the switch, and both of their other leads on one side of the cap's spot on the baord. Now wire the center pole to the other side of the cap's spot on the board. Thrown one way, C1 will be in the circuit. Thrown the other way, C2 will be in the circuit. What happens when you go in the middle? Both caps are on at the same time, adding their capacitance together, creating a third cap.
Title: Re: input cap switch: 3 different values.
Post by: Magnus on July 19, 2012, 02:19:37 PM
Hello,
here's the wiring-layout:

The cap in the middle is the smallest value, capacitors on top and bottom are added with their values when the switch is turned up or down  ;)

(http://img11.imageshack.us/img11/3042/threecapsoneswitch.jpg?http://imageshack.us/)


Greetings
Magnus
Title: Re: input cap switch: 3 different values.
Post by: poppyman on July 19, 2012, 02:43:38 PM
great :)

I'm sure it will sound awesome on my Jordan bosstone! thanks for your help.
Title: Re: input cap switch: 3 different values.
Post by: LucifersTrip on July 19, 2012, 03:24:42 PM
That works well, but I honestly haven't finalized any build that way since the caps are out of order. I think it is really cooler to have it go from small, medium, large in order...

I forgot what type of switch is the minimum to do that, but in one of the positions, the cap is in SERIES to lower the resistance

so, you have [original cap + series cap], original cap, [original cap + parallel cap] in that order...small to large

...or use a 3-way rotary
Title: Re: input cap switch: 3 different values.
Post by: davent on July 19, 2012, 04:40:56 PM
Could you just scrap the switch and go with a tone pot setup as in Joe Gagan's Easy Face. Works well in the Easy Face and Skyripper and worked great on the breadboarded Rangsmaster. Two caps and  a huge emphasize range to play with.

http://www.tonepad.com/getFile.asp?id=36

dave