Re: [buildcheapeeg] Optocouplers, Bus-system

From: Moritz v. Buttlar (info_at_baltic-microsolutions.de)
Date: 2001-05-21 13:20:36


Hi Joerg !

> It depends on what is best for the layout.
> Could you please post your brd-file as a base for making a decision ?

It isnīt ready yet. Iīm trying to evaluate the CNY65B optocoupler. The problem
is, that itīs quite slow and Iīm not sure what kind of circuit is required for
115kbaud operation. Some kind of Darlington configuration and a Schmitt-trigger
would probably do the job. My oscilloscope broke down as well :(
But I bought a new one, itīll be here in a couple of days :)

Just put the connector wherever you want somewhere on the border. BTW, if we
have a flexible cable, the exact position isnīt as important. I was thinking
about a direct connector (90 degree bended).

> What about the digital interface for the LEDs and switches. Would it be
> advantageous to add these signals to the bus-system ?
> It would give the possibility to design other cards, that can easily be connected
> to the bus, like a LC-Display unit with keyboard, or a memory card for
> storing EEG-data offline, etc.

OK, why not. Doesnīt make much of a difference if we have a 10 or a 20 signal
bus.

> This was the reason why I have modelled the amplifier input stage
> with voltage controlled voltage sources (however this is less accurate,
> because it is a very idealized form of an OP-amp) .

I think PSPICE student/evaluation version is freely available, have a look :).

Moritz

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