thumbwheel potmeter for left-right usage

Picture a remote control that you have to hold with the IR emitter forward. It has one thumb wheel coming out the left side, another coming out the right side. "Forward" would mean using the left hand thumb and pushing the left wheel towards the front, or using the right hand and moving the right wheel towards the front. Both should result in the same potmeter movement.

Or two shafts with the gears meshing half way between them. In this case that's the only option because the unit must be pretty flat, like a TV remote.

Have the pot wheel come out one side... flip over the whole control for lefties ;-)

...Jim Thompson

Unfortunately that doesn't work in this case :-(

Did you get the laser thing licked? Mine is humming but I am still not too enthused about the speed I am squeezing out of the TEC PID loop so far. It's like molasses.

as i noted in another post, 2 gears only, they come together to mess with each other. One gear is mounted on the Pot while the other, is mounted on a post. the 2 gears will be exposed side to side.

You would need a through hole or double ended POT for that.

That's what I was thinking of except that I wanted the shaft of the idler to be a pot also. Mainly because pots are so cheap and come with all the mounting etc. Else it would become a custom design.

Taking your description literally pushing the wheel towards the front would snap it off... so yes both result in the same non-movement.

I think I know what you're trying to describe by "push the wheel forwards" is push the top of the wheel forwards...

All you need is a pot you can stick a axle through...

On my old AM radio it hasn't snapped off in 30 years :-)

Picture a small AM/FM radio with a thumb wheel volume control on the left side of it. Those often have a similar thumb wheel for tuning on the right side. Now imagine these two mechanically linked and the radio not wider than the diameter of two thumb wheels. Can be done but the teeth on those wheels need to be coarse enough.

Again, that would make the unit too high. In this case it should be under 1/2". That pretty much limits it to thumb wheels, not regular knobs because they'd be too small.

MESH! MESH! MESH! MESH! MESH! MESH! MESH! MESH! MESH! MESH!

yeah... sounds you need pcb mount potentiometers that can mount gears...

maybe you could use a wheel with a rubber tyre on the left side. stick it on a swing arm so that users thumb pressure presses it against the pot enough to grip...

the pivot would be bolted to the PCB using a stepped bolt and a couple of washers, hmm, maybe just use copper pads instead of washers.

.---------------. ############ bolt | CASE | ############ | | ||||######|||||||||||| arm | | ||||######|||||||||||| |..... ____ | =====####===== washer/pad .WHEEL. / \\| xxxxxxxxx####xxxxxxxxxx pcb . . / \\ xxxxxxxxx

Excuse me, MESS, MESS, MESS, oh yeah and MESH , what you said.

Please don't slap my head right now. Got to bed at 3:00am last night ...

Nice! I didn't know mech CAD could be done in ASCII art. But still I'd prefer a 2nd potmeter for the left wheel just for the fact that it's cheaper and comes with all the mounting options.

Good idea. But mechanically it might be almost as complex as a specially made idler wheel that grabs into the knurls. If only the knurls are deep enough to be considered "teeth" one could simply use a 2nd potmeter of same type.

If the primary potentiometer shaft can take the side force and the thumb wheel is knurled to make such operation possible without slipping, try the following:

Mount a soft rubber wheel in contact with the primary such that the rotation will be in the direction you desire. Use a weak spring to keep the two in contact, but such that additional pressure on the secondary is transmitted to the interface between the two wheels.

Operating the secondary wheel should take no more thumb pressure than would be required to operate the primary if the rubber wheel/knob combo have a suitable coefficient of friction.

Nah. Hang the lefties from the ceiling by their feet.

Unless the knurls are actual teeth (on both wheels) you are going to have to arrange to have some side force applied to maintain friction. This will be a combination of a spring plus the force applied to the idler by the operators thumb.

Either using a second pot or an idler wheel, the idle shaft will have to be free to swing against the main pot wheel. If it is bolted down, any wear of either wheel's surface will result in proper contact being lost. Of course, for actual gears, both shafts can be fixed.

There is one alternative (if the device has the space internally). Drill a small hole in both the main and idler shafts (which can be fixed) and pass thin nylon string through one, wrap it around the shaft a few times and then around the other in the opposite direction. Bring it back to the main shaft and tie it to the loose end with a small tensioning spring in line. If there isn't enough room laterally, the string between the two shafts can be routed around a third shaft to provide enough free travel to incorporate the tension spring. This is how they used to couple radio tuner knobs to the variable cap. shafts.

The pots are actually only soldered in (thru-hole). They can be held in proper position by a clamping assy during wave solder. But this setup might not be good enough. Depends a bit on expected life. It's a semi-disposable application which is why it has to be cheap.

That might be an option. But probably we'll go with molded wheels where we can select our own teeth structure.