Mechanical Relay

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mjordan
 
Posts: 9
Joined: Mon Oct 03, 2011 7:58 pm

Mechanical Relay

Post by mjordan »

n00b question!

I'm working on a project that, among other things, will trigger the shutter release on my DSLR via the remote shutter. The DSLR's remote shutter provides its own 3.3V, so I need a mechanical relay to do this, and I think this one will work with my Arduino Uno?

http://search.digikey.com/us/en/product ... ND/1164329

The coil voltage is listed as 5VDC, which I assume means I can power it with the 5V from the Arduino? I'm quite new to electronics, and while I want to experiment, I also don't want to fry my Arduino. So I wanted to check here first. :)

Rukbat
 
Posts: 20
Joined: Mon Nov 07, 2011 12:15 pm

Re: Mechanical Relay

Post by Rukbat »

If you can find out what the current sink the camera needs, you can do it much better - with a transistor. A 2N2222 (or just about any small NPN transistor) will probably work, considering that the current demand is almost 0 (as far as any transistor is concerned). The Arduino can drive just about any transistor. The differences are:

Relay - slow (milliseconds). Transistor - fast (nanoseconds to a microsecond or two).
Relay - expensive. Transistor - cheap.
Relay - large. Transistor - small.
Relay - needs a diode to protect the Arduino. Transistor - doesn't.

And since the relay needs 72ma of current, you'll have to use a transistor to drive it anyway (the same one you could use to drive the camera without a relay).

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abqlewis
 
Posts: 71
Joined: Fri Dec 11, 2009 2:19 am

Re: Mechanical Relay

Post by abqlewis »

I agree with Rukbat's transistor suggestion. Also, for future reference, if you need help with electronic interfaces to the Arduino, a good place to start is http://arduino.cc/playground/Main/Inter ... thHardware. For example, they have a relay tutorial (hopefully it should tell you the relay you picked would probably wreck your Arduino), and they might have some transistor circuits in there.
BTW, what you really are doing with the camera, is interfacing a 5V device (Arduino) with a 3.3V device (camera interface). Google that, and you might get lucky. I was able to interface a 5V Arduino with a 3.3V UART using just 2 resistors in a voltage divider. It might not be optimal, but it was easy and it worked, so I just left it in, and it's still working.

Michael

mjordan
 
Posts: 9
Joined: Mon Oct 03, 2011 7:58 pm

Re: Mechanical Relay

Post by mjordan »

Thank you very much for the wisdom and the really useful link! I obviously have much to learn.

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