[sdiy] midi optocoupler isolation voltage?

[Paul Maddox]

Christian,

>Are there any tried and trusted methodes to
> limit the voltage difference between the midi devices? (varistors, spark
> gaps,neons...?)

none that I know of, but given that MIDI is a current loop, and if you check
out the schematics you could never have more than 5v on the midi line, spark
gaps and such are not really needed..

> I just wonder if electrostatic charge could be a problem since some midi
> devices are completely ungrounded (battery opperation etc...).

>From memory the MIDI IN connector SHOULD be grounded, so unless you have a
battery powered PC or Atari, you will probably have a ground.

> I try to design a midi to relay interface (a bit of "to reinvent the
wheel"
> ..but i love to invent, so its fun)
> I want to build the output stages with N-Channel PowerMosfets driven
direcly by
> CMOS ICs.

why not just use solid state relays?

> So far i only plan on the common EMF suppression (?) backward diode
parallel to
> the output (solenoid/relay...)
> any further tips that would increase reliability and/or electrostatic
charge
> withstand ?

Solid state relays, or if you're talking about mains voltages, check out
TRIACs..

Paul