Progressive resolution for a rotary encoder

[ataradov]

Hey, that's something. Thanks!

Agreed! I'll order a few just to have them on hand.

[Nusa]

Don't forget about the physical aspect - a big knob is better than a small knob.  For a large range you want to be able to "jog dial", if you have to grab the knob between your fingers to manipulate it, it's too slow to get it up to where you want it.  30mm is barely adequate, 40mm much better.

+1 , I love knob like this when it comes to rotary encoder that has the finger hole, as swirling single finger at that hole is really effective at high speed turn.

I wish I could find a reasonably priced source of these. The only ones I can find on Digi-Key are apparently made out of an alloy of 24k gold, platinum and titanium (with a tellurium plating for low noise). At least I assume they are based on the price! (Were talking $20-$50 each!)

There has to be an inexpensive source for them. They don't need to be machined aluminum (which the ones on Digi-Key actually are), plastic would be fine... I just don't get it.

https://www.aliexpress.com/item/32-13mm-Audio-Multimedia-Speakers-Aluminum-Knob-Knob-Guitar-Knob/32744452805.html

https://www.aliexpress.com/item/High-Quality-Knob-Audio-Volume-Control-Knob-Potentiometer-Knob-40x17mm-Round-6MM-Silver/32748541803.html

There's probably more. I only spent a minute looking.

Those are still really expensive. $4 and $7! Where are the sub-$1 plastic ones?

https://www.aliexpress.com/item/VK-Potentiometer-encoder-band-switch-plastic-knob-cap-32-5-13MM-flower-shaft-hole/32773845457.html

Here ya go, about 45 cents each shipped to US. But you gotta buy 100 of them for that price.

[ataradov]

Here ya go, about 45 cents each shipped to US. But you gotta buy 100 of them for that price.

Yep, ordered those.

[Cerebus]

Don't forget about the physical aspect - a big knob is better than a small knob.  For a large range you want to be able to "jog dial", if you have to grab the knob between your fingers to manipulate it, it's too slow to get it up to where you want it.  30mm is barely adequate, 40mm much better.

+1 , I love knob like this when it comes to rotary encoder that has the finger hole, as swirling single finger at that hole is really effective at high speed turn.

I wish I could find a reasonably priced source of these. The only ones I can find on Digi-Key are apparently made out of an alloy of 24k gold, platinum and titanium (with a tellurium plating for low noise). At least I assume they are based on the price! (Were talking $20-$50 each!)

There has to be an inexpensive source for them. They don't need to be machined aluminum (which the ones on Digi-Key actually are), plastic would be fine... I just don't get it.

Cliff K18, available with or without added weights to make them 'spinable' and give them a range of feels. http://www.cliffuk.co.uk/products/knobs/rotary.htm

[Cerebus]

I figured it would work out like this because the range is so high.  You want to change by as much as 10s of MHz per click down to 1s of Hz per click.  Selecting the digit doesn't  have to be ugly if you use the push button on the encoder.  I'm not sure how you display which decade you are changing but it should be manageable on the display.  Maybe you begin a sequence by pressing the button and it starts the MSD blinking.  Successive presses move the digit to the right.  After some delta T, the blinking goes away because it would be distracting.

Maybe when no prior adjustment has been made lately, the encoder itself moves the digit back and forth.  The pushbutton locks it in and successive encoder operations increment or decrement the count from that digit.

Something like that...

I've tried something similar in the past and found that using the press switch on the encoder had a tendency to jog a digit or two as you pressed the switch. I tried a reverse dead time to avoid this and I found that made the encoder seem unresponsive.

[ataradov]

Just an update on the final (so far) design, just in case anyone stumbles on this later.

It is basically the same stuff Siglent and others do, but without an encoder. I have 4 buttons - left, right, up and down. Left and right select a position (digit), and up and down change values starting from that position.

With this method, the rate of change can be predictable and reasonably slow. If you want to go faster - just go to a higher order of magnitude.

Another major benefit, which I actually use quite a bit - it allows for monotonic manual sweeps with arbitrary step.

[ataradov]

Just in case anyone interested why this question came up. Here is the actual project. This is is a signal generator up to 105 MHz (square wave only, lower frequencies have adjustable duty cycle) and frequency counter up to ~30 MHz.

This thing abuses SAM D11 in every possible way, but it still performs nicely. Most of the abuse is in the over-clocking peripherals by a lot, so obviously use at your own risk, and operation outside of normal temperatures is not guaranteed. It is still a nice project for home and hobby use.

All project files (hardware and firmware) are available at https://github.com/ataradov/siggen and PCBs can be ordered from OSHPark https://oshpark.com/shared_projects/lv69ij3V

[android]

And here's how to convert the cheap unweighted variety into the expensive weighted variety.
(Yes, I'm a cheap bastard )

[CJay]

Too late I'm sure but I'm thinking video recorder jog dial which typically had two switches per direction, first switch per direction was activated with a small turn CW or CCW and selected something like 2x speed play then the second switch was actuated if the dial was turned further and selected 4x or whatever speed play, would probably be fairly easy to make or even source

[ataradov]

One more update. Those encoder knobs from aliexpress have arrived. They are very well made and look and feel great. I can absolutely recommend them.