[time-nuts] TAPR "PulsePuppy" Pot Selection

[Dana Whitlow]

I think I need to clarify what I mean by "backlash".  It is not simple free
play in
the adjustment mechanism- it is something much more irritating, as follows:

I sneak up on the desired result, but manage to overshoot slightly.  So I
back
off on the screw, and find that at first the result continues to change in
the
*original* direction (making the overshoot even worse) for a bit before
finally
reversing as I wanted it to.  This behavior is not conducive to having a
good
time making critical adjustments, nor does it lend any confidence in the
stability
of the adjustment in the face of handling.

Dana


On Sun, Dec 24, 2017 at 4:06 PM, Charles Steinmetz <csteinmetz at yandex.com>
wrote:

> 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
>
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/m
> ailman/listinfo/time-nuts
> and follow the instructions there.
>