Sending a voltage from the DAQPad 6020E to a 5V relay

[auratech19]

Thanks for the advice Conseils, sorry I didn't give more specific information about the relays earlier.  I had a meeting to attend and I had to go buy those diodes from radioshack.  The sketch of the circuit I posted wasn't very clear, I know.  The circuit is set up the way Analog suggested in his model, though I haven't placed the diodes in it just yet.  I'll be working on that tomorrow and I'll give more specific details about the relay (I don't know off the top of my head, I'll have to look at it).  The power supply is just an AC to DC converter that plugs into a 120 VAC outlet and converts the signal to +12 VDC which feeds into the relay.  Thanks again everyone, the help is very much appreciated! 

[Conseils]

For the 12v solenoid it's possible that the unit will 'pull' significantly more current on actuation than during hold. You need to be sure that the power supply can handle this if your circuit is going to be reliable. Normally the solenoid manufacturer will specify an inrush current at some level. It depends a lot on the specific solenoid application but 2 times the normal holding current is not un heard of. If you don't look at this condition you could potentially overload the diodes in the power supply if it is a really simple type without current limiting. The transformer could overheat if you activate the solenoid too frequently, if the diodes will stand the strain. The thermal fuse in the transformer unit will then open and the transformer / power supply will be un-servicable. A fuse to protect the power supply might be a thought as well, something like a delayed action type. The specification of this will depend on the soelnoid specification. This will protect the circuits if the power supply is over rated (too large a current handling capacity) or if the power supply does not have an 'output current overload protection circuit' {the words here are important and not to be confused with 'thermally fused' or 'thermally protected' for example}.

It's likely at the moment that you have no load on the solenoid i.e. no controlled medium and this could affect the current as well.

Still it's not all bad.. for-warned is for-armed and even this condition can potentially be handled.. but a well specified power supply is the best option and it's worth checking out.

[Brian_Beal]

Your diagram shows that when the relay pulls in, it connects +12V to ground.  That can't be right.

[auratech19]

Well guys, thanks for all the help!  Everything is working great now and we can move on with our experiment!  The help is much appreciated!  Thanks again for everything!