[sdiy] dave smith *instruments*

[Ullrich Peter]

>> There is a huge problem with all these encoders failing in synths now though - all 
>the DSI stuff, Waldorf stuff, Alesis Micron, even older stuff like my Ensoniq ZR76...

Waldorf had a special problem in the Microwave I:
They connected the encoder wrong. Due to overlapping contact strips it worked for them 
during testing and maybe the first 2-3 years for you. But when the contacts have been used 
for some time the gray code pattern was as it should be in theory and due to the wrong 
connections it stopped working.

But the encoder itself was ok!
You just had to exchange two wires to the encoder and it worked.
I had to find the error on my own but some time later I read that this is a known error of the Microwave 1.

>Electro-mechanical encoders are nasty that way. I've got a PIC-base 
>project from about 10 years ago that's so bouncy now it's almost 
>unusable. DSI has a page with maintenance instructions that recommends 
>spritzing some Deoxit fluid into all the encoders periodically.

You can build an encoder that nearly works forever out of harddisk motors or stepper motors.
You can use the generated analog pulse patterns - amplified and pulse shaped like normal encoders.
Some DIY DJ projects use harddisk motors quite a lot. Search on google.
The stepper motor encoders have also been presented in the electronics magazine Elektor some time ago.

Here are some links to such circuits:
http://www.4qdtec.com/stpen.html
http://www.webx.dk/oz2cpu/20m/encoder.htm (nice project with PCB design!)

For my synth addon "datadial" (http://go.to/datadial ) I used normal mechanical micro encoders with 
pushbutton function as they are much smaller than the stepper encoder you could built... 
As I want to add it on front plates size matters as there is no much space left behind front plates...

Ciao
Peter

http://come.to/synpro
http://go.to/datadial (Synth Addon)