[time-nuts] TAPR "PulsePuppy" Pot Selection
Charles Steinmetz
csteinmetz at yandex.com
Sun Dec 24 22:06:10 UTC 2017
John wrote:
> I didn't really notice much backlash, though when setting oscillators I try to approach (slowly) from one direction until it's "good enough" and then stop, to avoid that problem.
The hot tip is not to just "sneak[] up on the sweet spot and then walk[]
away," as Dana put it.
Anytime you have an adjustment with some hysteresis (classic example is
setting a d'Arsonville movement to zero), you want to sneak up to the
perfect setting and then run the adjuster *back* the way you came just a
touch, to leave the adjusted part on its own without any mechanical
connection to the adjustor mechanism. Such contact is almost always the
culprit if the adjustment drifts after you set it.
This takes some "feel" for the motion of the adjuster mechanism, but it
is well worth investing the time to learn it by repeated trials of the
adjuster before you leave it alone.
Dana is spot on with his advice to tap the board (or whatever
mechanically supports the adjusted part) to make sure it doesn't drift.
If it does, you either failed to pull the adjuster out of contact with
the moving adjusting part, or the adjusted part just can't hold its
setting. In either case, better to know that now than after you button
the instrument back up.
Best regards,
Charles
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