Author Topic: beginner attempting small clone chorus  (Read 3468 times)

m2fu

beginner attempting small clone chorus
« on: December 11, 2005, 09:14:07 PM »
Hi, I am new to the world of building things electronically, and I am attempting the construction of a small clone chorus based on a pcb layout that I found.

But I wonder if anyone can help me with the meaning of a few of the parts:
1M Rev Log
100k Trim

What do those extensions (rev log and trim) imply?
I went out to a store and bought pots which have the same numerical values but I don't know if they are Rev Log or Trim.  :-\

I hope this doesn't sound like a dumb thing to ask, I am a beginner though.

Thank you.

petemoore

Re: beginner attempting small clone chorus
« Reply #1 on: December 11, 2005, 09:35:59 PM »
Hi, I am new to the world of building things electronically, and I am attempting the construction of a small clone chorus based on a pcb layout that I found.

But I wonder if anyone can help me with the meaning of a few of the parts:
1M Rev Log  :Reverse log is an audio taper, but reversed, for the Small Stone, having the right pot here means it'll have an 'even range' of control across the shaft rotation range. A 1m pot will 'do' all resistances between 0ohm and 1megohm, but in this application all the control of speed might be 'bunched up' near CW or CCW, the rest of the shaft rotation having little or no control to it.
100k Trim [Trim means usually something that can be easily adjusted to a 'certain R value' then left alone, a fixed resistor will do it's job...if it happens that it is the 'right' value for that position in the circuit...this is probly because the actual value needs to be 'tuned' to each circuit for best results]. I usually try to use board mount trimpots for these, but a 100k of any type should do the trick.

What do those extensions (rev log and trim) imply?
I went out to a store and bought pots which have the same numerical values but I don't know if they are Rev Log or Trim.  :-\ ...:the 1m you bought is most likely not Rev Log, however all speed ranges will be available using it, just very fine tune on one end of the shaft rotation, very coarse on the other, the 100k trim is probably a 'set and forget' trim, so whatever you have will probably do, might be a little 'fidgety-er' than a linear, usually trims work well as linear pots.

I hope this doesn't sound like a dumb thing to ask, I am a beginner though.

Thank you.
Convention creates following, following creates convention.

nelson

Re: beginner attempting small clone chorus
« Reply #2 on: December 11, 2005, 09:52:52 PM »
I dont recommend the small clone as a first project.

Build a fuzz, or a booster first. The small clone involves adjusting bias for the BBD.

If you dont know what a trimpot or a rev log pot is, I think you should definately attempt to familiarise yourself with the components by building other projects.

A trimpot is a PCB mounted mini pot that is usually set with a small screw driver in order to compensate for variable tolerences within factory made components, ie BBD's, JFETS, Germ transistors. In order to adjust for optimal performance, ie lowest distortion in the BBD.

a rev log pot is a reverse log potentiometer.

I would explain but the secret life of pots at www.geofex.com explains much more eloquently and with graphical representation of the pot sweep.

a 1m linear pot will work fine in the small clone, or alternatively you could wire a normal 1m log pot backwards, ie swapping the connections to lugs 1 and 3.


Good luck with the project. The small clone is a great effect.
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