17 ms·
> A potentiometer has a maximum and minimum value. They can’t spin indefinitely by the very nature of how they’re constructed, and each position of the pot maps
by kevin_thibedeau 3y ago
> A potentiometer has a maximum and minimum value. They can’t spin indefinitely by the very nature of how they’re constructed, and each position of the pot maps to a point on screen.
Some can spin freely if they have their stops removed. Tektronix did this for their late 70's vintage scopes like the 2465. The discontinuity from the wiper crossing the gap was mostly hidden with firmware.
- bsder 3y agoI'm pretty sure I've used that 2465, and I don't remember any of those pots not having a stop.
- kevin_thibedeau 3y agoThe cursor knobs are full turn. The service manual goes into some depth explaining how they work. If you play around you can find the gap where the cursors become non-responsive but in typical usage you skip over it and don't notice because the firmware is tracking the velocity and keeps them moving when the wiper is disconnected.
- tomn 3y agoI have a bench power supply which takes this further by having two stop-less potentiometers on the same shaft with a 180-degree offset to cover the gap. It works quite well!
- nicole_express 3y agoWhen I wrote that I assumed it was a physical possibility but I didn't realize people actually did that. It would actually probably work pretty well for a Pong system, since the discontinuity would be when the paddle was off-screen. But I don't know if any system actually did that.