Simple and Cheap, Multi-Turn Pots

[chemelec]

Multi-Turn Pots are Expensive. But 10, 18 or 25 Turn Trimpots are CHEAP.
A Short piece of 1/8 Inch Brass Tubing (From Hobby Shops) can be soldered to the Brass Screw Adjustment on these Trimpots, And than can be fitted with a knob for 1/8" Shafts.

Make sure the Brass Adjustment and the Inside of the Brass tube are Clean.
Carefully Than Pre-Tin the Top of the Brass Screw and partly fill the inside of one end of the tube.

Be Careful to Position it Sraight near the trimpot, than using a Weller Soldering Gun,
Heat the Tube to melt he solder in it, Than place it onto the Screw and Quickly Remove the Iron.

If all goes well it will be Straight and work really good.
On MY FIRST ATTEMPT at this, I had to Re-melt the tube Two times to get it Straight, But still didn't damage the trimpot.

[greylourie]

Handy modification. Thanks for this.

[mschmahl]

Nice idea. Thanks a lot.

[mohandes]

Multi-Turn Pots are Expensive. But 10, 18 or 25 Turn Trimpots are CHEAP.
A Short piece of 1/8 Inch Brass Tubing (From Hobby Shops) can be soldered to the Brass Screw Adjustment on these Trimpots, And than can be fitted with a knob for 1/8" Shafts.

Make sure the Brass Adjustment and the Inside of the Brass tube are Clean.
Carefully Than Pre-Tin the Top of the Brass Screw and partly fill the inside of one end of the tube.

Be Careful to Position it Sraight near the trimpot, than using a Weller Soldering Gun,
Heat the Tube to melt he solder in it, Than place it onto the Screw and Quickly Remove the Iron.

If all goes well it will be Straight and work really good.
On MY FIRST ATTEMPT at this, I had to Re-melt the tube Two times to get it Straight, But still didn't damage the trimpot.

nice work but what is the connection to the multi-turn

[chemelec]

nice work but what is the connection to the multi-turn

10, 18 or 25 Turn Trimpots are MULTI-TURN.

[Polymer]

Chemelec:

Just found the solution to my trimpot --> external knob problem HERE. THANK YOU!

[joop]

Thanks for sharing!

[lucifer]

The problem of using trimpots as a replacement for multi-turn pots is their short life: about 200 rotational cycles or so...

[chemelec]

The problem of using trimpots as a replacement for multi-turn pots is their short life: about 200 rotational cycles or so...

Possibly may be true, but I am using one on a PinPointer I built, and it has been working Good for Much, Much More than just 200 rotations. (So far over 2 years of use.)

[Polymer]

Hmmm, what a dilemma for me. I couldn't believe the "only 200 rotations" part. Checked the specs of a few manufacturers and !$&"#* it's true.
The real multiturn pots have 300000 up to 1000000 rotations as a minimum life. If they would only fit in the housing ...

Chemelec: What brand of trimpot did you use? Perhaps some are better than others.

[Jerry]

Possibly may be true, but I am using one on a PinPointer I built, and it has been working Good for Much, Much More than just 200 rotations. (So far over 2 years of use.)

Just my opinion but I suspect it will last far longer. In day to day usage the control is probably just tweaked a bit if moved at all rather than turning it from stop to stop. Will take a long time to get the amount of use that would equal 200 rotations.

Jerry

[green]

Just my opinion but I suspect it will last far longer. In day to day usage the control is probably just tweaked a bit if moved at all rather than turning it from stop to stop. Will take a long time to get the amount of use that would equal 200 rotations.

Jerry

The 200 rotations is for a 3% change in resistance, probably won't matter for a trimmer pot.

[chemelec]

Chemelec: What brand of trimpot did you use? Perhaps some are better than others.

This particular one says "Tech" on it.
Some others I have used on other projects were just some Old ones I removed from older Equipment.

But so far I haven't had any problems.