bad precision pot?

[Fraser, Colin J]

> -----Original Message-----
> From: jorgen.bergfors at idg.se [mailto:jorgen.bergfors at idg.se]
> Sent: 10 August 1999 11:33
> To: Colin.Fraser at scottishpower.plc.uk; synth-diy at mailhost.bpa.nl
> Subject: RE: bad precision pot?
> 
> 
> >I'll need to crack a spare one open and see what's inside.
> 
> You will probably find it identical to a single turn, except 
> that the wiper is driven by a worm gear, instead of directly. 
> This is if it is the vertical type with the setting screw on top.
> The oblong type more resembles a slider. In this case the 
> wiper has a nut that is moved by turning a screw. I suppose 
> this type has slightly better settability than the vertical 
> type. Any comments?

I've used the horizontal mounting type more often, for vco scaling on some
3340 oscs. They haven't needed any adjusting for a couple of years. They do
take up a fair bit of board space.

I wonder if it would be useful to build a single turn preset adjusting tool
from a vernier dial (connect a screwdriver blade to the shaft, hold it with
one hand and adjust with a 10-1 ratio with the other)
The Pro-one vco adjustments are always a bit hit and miss, and there's no
room under the panel for a multi-turn preset.


Colin f