Multi Turn Trimmer as a Potentiometer

[Gold]

Does anyone have a trick for using a multi turn trimmer as a panel mount pot? Multi turn pots are pretty expensive. This is for occasional calibration use.

I’ve thought about gluing a tube to the screw adjuster. Then glue a pair of shoulder washers to the tube to keep it in the hole in the chassis.

 

[Ike Zimbel]

Will the trimmer be soldered into a circuit board? If so, that's probably enough to hold it in place. In which case you just need to have the screw adjuster poke through the front panel.
For reference, I replaced the Bus Trim pots on a Neotek Elite with multi-turn trimmers in 2003, and they are still working fine. In that case, I put single machined-pin sockets in the PCB where the pot mounted and then put the leads from the trimmer in the sockets.

 

[JohnRoberts]

I think I recall seeing old "vernier" (unsure of the name?) knobs that provide a mechanical divider for more rotational resolution.

JR

 

[Gold]

Will the trimmer be soldered into a circuit board?

It could be mounted on perf board or something for mechanical reasons but not on the circuit board that it is controlling. It is to replace a pot on a faceplate.

 

[ruffrecords]

Some types off multi turn trimmers have front panel adaptors:

https://uk.farnell.com/hylec/5356-5355-5362-13/adaptor-panel-mount/dp/149877

Cheers

Ian

 

[Gold]

Some types off multi turn trimmers have front panel adaptors:
https://uk.farnell.com/hylec/5356-5355-5362-13/adaptor-panel-mount/dp/149877

Thanks! That's exactly what I was looking for.

 

[Ike Zimbel]

Just found a pic of the arrangement I mentioned in reply above:

 

[Gold]

Just found a pic of the arrangement I mentioned in reply above:

How are they attached to the faceplate? If they aren't attached to the faceplate it looks precarious. Any pressure on the on the trimmer from a screwdriver could move it around in the socket. Not a big fan of stuff loose in a socket anyway.

I ordered Bourns 3006 trimmers with the H-83P panel mount adaptors. Using these is about 1/3 the price of multi turn potentiometers like the Vishay 534 that I've been using.

 

[swpaskett]

I have 10 to 20 panel mount trimmers in my collection. These mount like pots in a hole a little under 1/4 inch diameter. They extend about an inch behind the panel and have 6 inch wire leads. I think they are all 10K 10 turn. PM me if you want them for the cost of postage. I'll never use them.

 

[swpaskett]

Or try this: G21695 - WEEKEND DEAL! (Pkg 2) Bourns® Panel Mount 100K 25 Turn Trimmer Resistor 272-582-104M

 

[JohnRoberts]

looks like I remembered the name correctly "vernier" knob.

Found these on ebay, I never used one but vaguely recall seeing them on some old gear.

JR

 

[Ike Zimbel]

How are they attached to the faceplate? If they aren't attached to the faceplate it looks precarious. Any pressure on the on the trimmer from a screwdriver could move it around in the socket. Not a big fan of stuff loose in a socket anyway.

I wondered about that too! It looks to me like they are held against the panel by the bodies of the 3-pin SIP sockets (not individual pins as I implied earlier), and then the circuit board is held in place by the usual mix of pot and switch hardware and L-brackets. It's been working fine for 19 years now, although I don't think they get tweaked often, if ever.

 

[Gold]

looks like I remembered the name correctly "vernier" knob.

Found these on ebay, I never used one but vaguely recall seeing them on some old gear.

JR

 

[Gold]

For a multi turn pot you would need one of those dials that has a click stop display for the number of turns.

 

[Gold]

I have 10 to 20 panel mount trimmers in my collection. These mount like pots in a hole a little under 1/4 inch diameter. They extend about an inch behind the panel and have 6 inch wire leads. I think they are all 10K 10 turn. PM me if you want them for the cost of postage. I'll never use them.

I'll take them. Thanks! I'll send a PM with my address.

 

[Gold]

Or try this: G21695 - WEEKEND DEAL! (Pkg 2) Bourns® Panel Mount 100K 25 Turn Trimmer Resistor 272-582-104M

I saw that style but Mouser and Digikey were out of stock. I like the Bourns style I ordered which uses a regular long trimmer and a plastic panel mount piece that the trimmer slides (and hopefully snaps) into place.