Optocoupler to control camera?

Jaggermax

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To all of the electronics guys out there, I have a question.  Can an optocoupler be used to directly close the shutter wires for the camera?  I had been using a darlington array driver attached to the coil of the relay and the camera leads across the N.O. pins of the relay.  I was wondering if I could just directly connect the output port of my controller to the input of the optocoupler and then the camera wires across the output of the coupler.  I was not sure how much current capacity was needed, but I figured it would not be much since the shutter wires have only 3 volts between them.  Any thoughts?  
 



Archilochus

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Hi Jaggermax,
Sure, I use 'em for most of my cams.  Be aware that certain cams use different means of being triggered - so that some cams need a 'common' emitter and some use a 'common' collector to trigger.  Some cams seem to work either way - but most I've tried work best with the common emitter.

Archilochus
 

Jaggermax

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Thanks Arch. Sure will make the circuit a lot easier without having to use a driver and a relay (and cheaper!).  On the Vivitar BV85 camera, between the two wires is three volts.  Should I connect the more positive lead from the camera to the collector of the opto output and the negative lead to the emitter?  Also, is anything else needed to hook up to the output of the opto like a pullup resistor on the collector?  Or is it just as simple has just hooking up the wire to the output?  
 

Archilochus

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Hi Jaggermax,
That's what I'd try first - the emitter to the more negative side.  If it does not work, try it the other way around.  On the cams I've used with optos, I've never needed any other components on the output side.
I use a 1K resister on the input LED (NEC 2501 type opto) which keeps the power low.
Other advantages of optos are the wide operating voltage, they are virtually indestructible, and no back EMF - so no protection diode needed.

Archilochus
 


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