Re: Isolated pulse detector

From: Joerg (notthisjoergsch_at_removethispacbell.net)
Date: 10/19/04 

Date: Tue, 19 Oct 2004 17:17:10 GMT

Hello Sylvain,

The zener and second resistor is often not necessary. An opto coupler
with a plain diode input characteristic limits the voltage across it by
itself. You might want to include a reverse diode across the opto
coupler input if you suspect that ringing might occur on this line.
That's always a good idea and cheap.

If the coupler has too narrow a current range you may have to replace
the resistor with a current source but that can be easily achieved with
a couple of transistors and resistors.

Regards, Joerg

http://www.analogconsultants.com