EEVblog1573 - TEARDOWN: How a Rotary (Angle) Pulse Encoder Works - Page 1
Forum section: electronics / general

author: EEVblog
author_rank: Unknown
timestamp: October 18, 2023, 10:40:12 pm
content: How a Rotary (Angle) Pulse Encoder works. This is entirely different to the normal quadrature phase encoder you have used before.A teardown from the Haefely Trench PESD 1600 ESD Tester.00:00 - This is NOT a regular quadrature rotary encoder!02:08 - Tool Tip, Pin Vice05:41 - EDC tool shootout, Victorinox MiniChamp vs Gerber Dime vs Olight Otacle06:34 - We're in like Flynn!07:13 - New Lab Jack for the Tagarno microscope08:09 - Of course that's how it works09:59 - Why is this not used more often?12:29 - How it works14:49 - Is there another example of this type of encoder? if not, why not?

author: pickle9000
author_rank: Super Contributor
timestamp: October 18, 2023, 11:05:56 pm
content: Reminds me of a rotary telephone switchpack. Would not surprise me if it was designed by an old telecom guy (or gal).

author: EEVblog
author_rank: Unknown
timestamp: October 18, 2023, 11:57:23 pm
content: Quote from: pickle9000 on October 18, 2023, 11:05:56 pmFor sure!

author: Froese
author_rank: Newbie
timestamp: October 19, 2023, 03:11:58 am
content: The advantage of this kind of rotary encoder with toggle switches is, that you can debounce them perfectly with a simple RS-flip-flop (the two toggle contacts of each switch on set- and reset) or an equivalent programm, without the need for an arbitrary dead time or delay.

author: Dundarave
author_rank: Regular Contributor
timestamp: October 19, 2023, 04:39:01 am
content: That extra piece of what looks to be springy metal may have been placed around the geared part somehow in order to take up any radial “slop” in the mechanism, like a backlash preventer.It looks like it could only fit inside the package if it was flexed and constrained by the case itself.

author: Kleinstein
author_rank: Super Contributor
timestamp: October 19, 2023, 11:50:46 am
content: For the SW decoding the difference is not that large. One you get the idea right the quadarture decoder is not that difficult and one can even tolerate bouncing of single contacts.It can make a difference if one wants direct logic for counting - e.g. 2 Flip-flops for debounce and than counters.

author: Rdx
author_rank: Contributor
timestamp: October 19, 2023, 05:00:53 pm
content: Wow, the mechanical design of this thing is much (much!) simpler than I expected. Was pretty sure there would be some surface contact wipers, which I would have expected to be a possibel failure point...It seems EBE also offers other interesting types like Step + Direction pins (eg, kind of like you would control your stepper motor driver)

author: Peabody
author_rank: Super Contributor
timestamp: October 19, 2023, 05:15:29 pm
content: Quote from: Froese on October 19, 2023, 03:11:58 amCould you explain how the flip-flop would work to deal with bouncing? Perhaps a drawing? Each switch first makes contact, then if it bounces, it breaks, then remakes. But what differentiates that bounce from a "real" movement to the next detent?Edit: Ok, I see. It's because it's double-throw.

author: SiliconWizard
author_rank: Super Contributor
timestamp: October 19, 2023, 06:52:18 pm
content: One drawback is that it can only be implemented as a rotary encoder with detents. If you want a no-detent kind...

author: Fryguy
author_rank: Regular Contributor
timestamp: October 31, 2023, 06:00:12 pm
content: Hey Dave , you put the shorter spring exactly where it belongs - now the second , longer one goes to the opposite side of the case and pushes on the head of that white , hammerlike part ! That wide center hole in the hammer is necessary for the movement . . .

author: Wollvieh
author_rank: Contributor
timestamp: November 03, 2023, 03:24:40 am
content: One unique advantage of this design is that you could use it in principle whereever you have a plus and a minus key without changing hard- or software.Just add 3-4 wires, hot glue the Encoder to the case or drill a hole if you dare and you have ergonomized your old piece of sh^W equipment.Contact bouncing should be no problem, as the original keys have to be debounced somehow. Only problem could be the speed, as often even manual human inputs are too fast for the debouncing electronic.Everybody knows the - attention, german term - "Mäusekino" of the 80ies and 90ies: Tiny displays (like "cinema for mice" which is the meaning of the term), but above all tiny clicky buttons on everything, no more potentiometers for turning. Be it car radios, car air condition, lab/measuring equipment, Hifi-stuff. Absolutely everything needed 20 to 100 pushes on the same key to get from one end of the scale to the other.HP for example added one single rotary encoder on the devices above some thousand bucks, but in cars even mid 2000 years there were air conditions with keys, where you have to push an absurd 32 times to get from 16 to 32 degrees C and vice versa, or 10 steps for the fan from low to high.I am sure all manufacturers of that unergonomic stuff knew about this kind of encoder. And they knew that they would never be allowed to spend 6 Euros each. So millions of people had and still have to push billions and trillions of dome and rubber buttons everyday in staccato, instead of comfortably turning a knob.Luckily at least the aviation industry spent more money, so the autopilots still work on turning knobs as in analog times. So the pilots save at least 15 minutes per flight of button-pressing like mad.