[sdiy] Shaft Encoders (was "illuminated switches")

[Eric Brombaugh]

Olav Martin Kvern wrote:

> Electronics Goldmine is amazing--between them and All Electronics, I'm a 
> happy builder. Also, their sale on Panasonic rotary encoders:
> 
> http://www.goldmine-elec-products.com/prodinfo.asp?number=G16267
> 
> ...deserves mention. These are of incredibly cheap manufacture (the pins 
> actually seem to be some sort of foil that comes apart with even minimal 
> breadboard stress), but they work very well. With a push switch, even.

I got a batch of these from them today (quick delivery - EG is about 
20mi away from me) and thought I'd highlight a few things I found out:

* They have a shaft push switch included - Yay!
* The quadrature signals don't go through a full cycle for each detent - 
Boo! Rather, the detents are every 90deg in the quadrature sequence. 
This behavior makes these encoders incompatible with the more common 
Alps variety where the detents are spaced every 360deg in the quadrature 
sequence. Firmware and/or hardware decoders designed for Alps won't work 
correctly with these encoders - you'll have to cycle through 4 detents 
on these encoders to register 1 pulse on a decoder designed for Alps.

Note: all this info can be inferred from the detailed description on the 
EG web page. I just didn't read carefully enough.

That said, they seem to be perfectly nice devices - fairly sturdy 
construction (aside from the thin pins Olav mentioned), nice viscous 
feel to the rotation and shaft push and the price is right. It wouldn't 
be hard to design a different decoder for these guys, just be aware that 
you may have to if you're used to the other type.

Eric