On 9/25/06, Michael Rigby-Jones <Michael.Rigby-Jones@bookham.com> wrote:
>
>
> >-----Original Message-----
> >From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu]
> >Sent: 25 September 2006 11:26
> >To: 'PICLIST'
> >Subject: [EE] I need a circuit for a bidirectional opto
> >isolated TTL interface
> >
> >
> >I was thinking of using HEX inverters and opto isolators that
> >basically are two unidirectional circuits back to back.
> >
> >Works in simulation but do not know how well it will work in
> >the real world :-(
> >
> >I want to opto isolate the JTAG programmer interface from the
> >real world as I may otherwise and with Murphy's Law help blow
> >up my programmer :-(
>
> The first problem is likely to be speed related, common/cheap opto-isolators are v..e..r..y  s..l..o..w.


6N137 it's a common/cheap one (about $0.6 here if you buy one):
http://www.datasheetcatalog.com/datasheets_pdf/6/N/1/3/6N137.shtml

Vasile
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