[sdiy] Trimpots

[Harry Bissell]

I'd call that a "pot' with no shaft or knob.

Its a user control. A 'trimpot' is to adjust parameters you really want
fixed but can't. 

example: The zero and range on a VCO expo. You would NOT want to twiddle those, nor would
fixed resistors do the job.

Semantics... :^) I guess you might call them "user adjustable trimpots" vs "no user serviceable parts inside"\\

H^) harry 

----- Original Message -----
From: dan snazelle <subjectivity at hotmail.com>
To: Harry Bissell <harrybissell at wowway.com>
Cc: synthdiy diy <synth-diy at dropmix.xs4all.nl>
Sent: Tue, 09 Aug 2011 10:13:34 -0400 (EDT)
Subject: Re: [sdiy] Trimpots


 a trimpot can be in a circuit to allow for variation 

maybe it wasnt a good idea but I included one on my Tracer City filterbox to allow for different ranges of input signal...for example a guitar might sound better with the INITIAL cutoff at one point and Drums at another

so I added it to the bottom of the PCB which is easily accessible....I like knowing that I can change the character for each and every box with a simple 30cent trimmer and a screwdriver.





On Aug 9, 2011, at 8:45 AM, Harry Bissell wrote:

> Just a side note (sorry I've been napping a bit here :^)
> 
> Measuring a trimpot from one unit, and copying the setting to another unit is
> generally useless. Designers do not EVER include trimpots unless they cannot predict
> the resistance value they need because of other (unknown or unknowable) variables.
> 
> You may as well set the trimpot to mid-rotation, as a good designer will calculate the
> nominal range they want to lie at or near that point. The value of the trimpot gives you
> an idea as to how variable the setting needs to be.
> 
> Offhand, I didn't understand what the trimmers in the (was it) Emulator are for, or I'd try to
> be more helpful. I think you should probably look at some circuit points on the scope and
> twiddle the pots, try to figure out what they are supposed to do...
> 
> (I'd be very wary in a power supply, the thing might become unstable etc.
> 
> otoh... Sometimes, a bad designer puts in a trimpot they really don't need...
> 
> H^) harry
> 
> 
> 
> 
> Synth-diy mailing list
> Synth-diy at dropmix.xs4all.nl
> http://dropmix.xs4all.nl/mailman/listinfo/synth-diy
> 
> -- 
> Harry Bissell & Nora Abdullah 4eva
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at dropmix.xs4all.nl
> http://dropmix.xs4all.nl/mailman/listinfo/synth-diy
> 


-- 
Harry Bissell & Nora Abdullah 4eva