Antwort: Re: [sdiy] midi optocoupler isolation voltage?

[Christian.Bergmiller at daimlerchrysler.com]

I want to build 64 Outputs to drive solenoids.
Solid state Relais are too pricey in this quantity
(and i think they would be not necessary for switching 12V 200mA per Cahnnel)

This thing will be the interface an electromechanical played Instrument (pipe 
organ/chimes)

Christian

>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