> > Full circuit please.

> http://www.angelfire.com/mech/homerov/rocket/schem.jpg
>
> here it is, but the output is darlington

OK - that's a fairly complete circuit.
Actual values used may be useful - eg what is value of resistor in series
with opto?
Is it 5V supply?
What is opto current gain diode to darlington at 10 mA WORST CASE.

I found a datasheet for an NTE3045 opto here

        http://www.nteinc.com/specs/3000to3099/pdf/nte3045.pdf

6 pin darlington. May well be different.
Gain was 5 at 10 mA LED current.
2v max forward LED voltage at 10 mA. 1.15v typical.



IF the optos are the same and IF you are getting 10 mA LED current then you
can expect about 50 mA before the opto output lifts out of saturation. ***
What current does the shutter need? ***
= *** If you place a mA meter across the contacts that the transistor is to
switch, what current flows? ***


To get 10 mA at 5v the series resistor would need to be less than about
(5-2)/10 mA = 300r.
*** How large is it? ***



        RM

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