making a toggle switch that swaps between 2 caps

Started by Ocoaibass, March 03, 2012, 11:21:44 AM

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Ocoaibass

I've installed trim pots on resistors, but is there somewhere i :icon_cry: could learn how to put a toggle on a cap? Here's what I'm doing:

I got a Rat 2 & did the double Ruetz mod. I increased the 4.7uF cap connected to the 560ohm resistor to 10uF. It gave a deeper frequency for the sweep of the trim pot. I want to swap the 2.2uF to 4.7uF (I've already got the previous cap I pulled) but I thought that it might make an interesting option to be able to swap one or both caps' values back & forth. Who knows. It might make for an interesting variation.

When I say how, know that I'm a serious novice. Explanations are good, but I'm going to need to be pointed in a how to direction. I'll do the grunt work, but I have no idea what this would even be called, so I don't quite know how to look for it online.

arma61



Hi

one of the best resource, it's on my favs.

http://www.beavisaudio.com/techpages/Switches/

have a read, and you will figure out your solution.... and many other  ;)

"it's a matter of objectives. If you don't know where you want to go, any direction is about as good as any other." R.G. Keen

Pollinator95

*SPOILER ALERT* If you want to figure it out from the link above, don't look at this yet.















Use a DPDT switch.
WARNING: I AM A NOOB

ashcat_lt

Don't we try to avoid switching caps like that?  The caps will store a voltage while disconnected and then rapidly discharge when switched back in.  This could cause a noticeable popping sound.

Better would be to wire two 4.7s in series (total is close enough to 2.2) and use an SPST to short one of them.

Pollinator95

That's true, hadn't really considered the values. In any case, I don't think he's going to swap values mid-song  :icon_lol:
But yeah, listen to ashcat.
WARNING: I AM A NOOB

Ocoaibass

After reading the section on switching at Beavis Audio (thanks for the link) I think I know what you're talking about, but no switching mid song. I assume it's just a nuisance issue, like True bypass switching.

I'm also swapping for Mylar caps, since I'm installing all new stuff.

CodeMonk

Quote from: Pollinator95 on March 04, 2012, 01:03:37 PM
That's true, hadn't really considered the values. In any case, I don't think he's going to swap values mid-song  :icon_lol:
But yeah, listen to ashcat.

Keep in mind that I am just getting over the flu....
Perhaps something along the lines of a pulldown resistor for the pop?

seedlings

You may have less of a pop if you leave the larger cap always connected, and switch in (short out) a smaller cap in series.  Note the result will make the switched cap effectively smaller than it's rating. 



Plus you can use an on-off-on switch and then have 3 selections.  Middle will be fattest, then choice of two smaller caps on either end. 

CHAD

ashcat_lt

Neither of those do what you've described in either of your statements.

With a double throw switch you could run the input to the left lug, put one cap between that lug and the middle lug, another cap between middle and right hand with output (ground in this case) on the right hand lug.  Only needs one pole. 

With an On/On switch you'd get one cap or the other with the unused one shorted.  On/Off/On would give Cap A/Cap A + Cap B*/Cap B.  On/On/On would give Cap A/no cap(input straight to output)/Cap B, which in this case is a Bad Thing! (If I'm not mistaken the OP has recently seen what "no cap" does here)

>--L--||--L--||--L-->  where L is a lug.

seedlings

Quote from: ashcat_lt on March 05, 2012, 04:26:01 PM
Neither of those do what you've described in either of your statements.

With a double throw switch you could run the input to the left lug, put one cap between that lug and the middle lug, another cap between middle and right hand with output (ground in this case) on the right hand lug.  Only needs one pole. 

With an On/On switch you'd get one cap or the other with the unused one shorted.  On/Off/On would give Cap A/Cap A + Cap B*/Cap B.  On/On/On would give Cap A/no cap(input straight to output)/Cap B, which in this case is a Bad Thing! (If I'm not mistaken the OP has recently seen what "no cap" does here)

>--L--||--L--||--L-->  where L is a lug.

Ehh... did I give some bad advice?  My first statement was basically the same as you described by shorting out one cap in series.  The second statement, you're right.  SPDT on-off-on is how I wired it, not DPDT.



Apologies,
CHAD

ashcat_lt

It's just that the pictures you've drawn just don't do the things that you've described.  Generally good advice in the text, and the pictures look like they'll work, too.

My idea of best practice when switching caps is that both ends of all the caps should be connected to the circuit at all times.

PRR

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