Author Topic: Capacitor on pot  (Read 6942 times)

conksu

Capacitor on pot
« on: October 03, 2005, 09:18:28 AM »
Hi, noob question here, sorry if this has been answered before.  What is the the function of the capacitor between the 2nd and 3rd pot lugs in the NPN booster?  I've recently built this and noticed if you turn the pot quickly, it takes a second for the boost to catch up.  I figured the cap made this happen, but I don't quite understand the function.

aron

Re: Capacitor on pot
« Reply #1 on: October 03, 2005, 01:30:41 PM »
Like most boosters there's a capacitor there to increase the gain of the circuit. If you try and take it out (lift one leg of the capacitor) you will hear the difference.

conksu

Re: Capacitor on pot
« Reply #2 on: October 03, 2005, 02:49:16 PM »
So, the pot is actually adjusting the use of the capacitor?  Meaning, if you hooked up the capacitor without the pot, it would work, but it would be at full gain all of the time?

aron

Re: Capacitor on pot
« Reply #3 on: October 03, 2005, 05:24:24 PM »
It is adjusting the amount of signal being bypassed yes.

Check out:

http://www.allaboutcircuits.com/vol_3/chpt_4/10.html
« Last Edit: October 03, 2005, 05:28:06 PM by aron »

conksu

Re: Capacitor on pot
« Reply #4 on: October 03, 2005, 09:13:46 PM »
So would changing the cap value increase the gain?  Or would it be better to try different transistors?

aron

Re: Capacitor on pot
« Reply #5 on: October 04, 2005, 02:07:31 AM »
The cap affects what frequencies get rolled off, so a smaller cap value will effectively roll off more lows. You could increase the power supply for more boost. It should have plenty of boost as is.

conksu

Re: Capacitor on pot
« Reply #6 on: October 04, 2005, 11:09:27 AM »
Hmm, I built this project and it sounded great through a small SS practice amp but when I plugged it in to a 60w tube amp, there was a boost, but it was very subtle.  I was using an old 9v, could this be the issue?  I have a DMM, but I couldn't find a post that gave the voltages I should be getting to troubleshoot.  Could you possibly direct me?

I appreciate your help.

KORGULL

Re: Capacitor on pot
« Reply #7 on: October 04, 2005, 06:32:01 PM »
I've found that this pedal works differently depending on if I'm using it on the amp's clean or dirty channel.
-Clean channel=large volume boost.
-Distortion channel=practically no volume boost, but a nice gain/distortion boost.

aron

Re: Capacitor on pot
« Reply #8 on: October 04, 2005, 06:37:55 PM »
Yep, use a new battery. As for the booster with clean vs. non-clean, think about it, it's always doing the same thing. It's how your amp reacts to a larger input signal which is the key.

borman09

Re: Capacitor on pot
« Reply #9 on: May 02, 2011, 01:41:25 PM »
You will be careful about the signal.