I need a relay.

"Rusty Vandura - www.tinyurl.com/keepoppo" (rustyvandura) 03/04/2016 at 11:31 • Filed to: None

0

10

* 5VDC control voltage,
* switching 12VDC @ 1.0 amp,
* closed when energized and
* able to remain energized/closed for 8 hours per day, 5 days per week.

Where would I find such a thing?

RWS Motorsport > Rusty Vandura - www.tinyurl.com/keepoppo 03/04/2016 at 13:32

0

RS Components, if you’re in the UK/Europe. (turns out its called Allied Electronics in the US) is what we use for this sort of thing at work.

or Sparkfun if its more for Arduino style https://www.sparkfun.com/products/100 Will switch 12v, 5A. run off 5V (not sure of current needed to make it switch though)

they normally state a number of cycles. And you’re looking for a Normally open or NO style (if you didnt already know :) )

Rusty Vandura - www.tinyurl.com/keepoppo > RWS Motorsport 03/08/2016 at 10:27

0

Thanks for the reply. I missed it originally. I need to plug the relay into a USB port so that it draws the 5VDC when the device (an LCD projector) is turned on and closes the relay to switch the 12 VDC 1.o amp and power an accessory fan. So the relay would remain energized — and closed — for six to eight hours at a stretch.

Wouldn’t the control voltage amperage be miniscule?

I don’t know whether to consider this relay to be NO or NC.

Thoughts?

RWS Motorsport > Rusty Vandura - www.tinyurl.com/keepoppo 03/08/2016 at 13:20

0

So that would be a normally open, because its closed when its energised. I dont know how much current a USB port can put out, but I would think it would be fairly easy to find out (quick google suggests up to 500ma (0.5A)). In which case you need to find a relay which can be switched at that voltage & current. I presume the USB port will be powered at all times, so the act of plugging the device in should energise the relay and connect the 12v, turning on the fan.

Just looked at the datasheet of the Sparkfun relay and yep, that should run off 37ma, (0.037A) so the USB should power that, and switch. That relay has 2 poles, a NO and NC, so you’ve got the choice but I would think you want the NO side, so it turns on when plugged in. Easiest way to check is when you have it, plug it in to power and use a multimeter to check continuity on the switching pins to see which are connected when energised. Or read the datasheet, but thats basically cheating :D

Rusty Vandura - www.tinyurl.com/keepoppo > RWS Motorsport 03/08/2016 at 14:13

0

Thank you for the assist.

RWS Motorsport > Rusty Vandura - www.tinyurl.com/keepoppo 03/08/2016 at 14:14

0

More than welcome, happy to help a fellow Oppo. If you get stuck/have any more q’s just shoot.

Rusty Vandura - www.tinyurl.com/keepoppo > RWS Motorsport 03/08/2016 at 14:21

0

Yes, that looks like just what the doctor ordered.

Rusty Vandura - www.tinyurl.com/keepoppo > RWS Motorsport 03/08/2016 at 15:25

1

This is my project. The projector vents right at me while I’m teaching and I am ducting the air away from myself. The external fan, right now, I have to plug and unplug. I want it to switch on and off automatically with the projector. I searched for a 5V fan to power straight from the USB port on the projector, but I could only find 12V fans. I have a 12VDC transformer...

RWS Motorsport > Rusty Vandura - www.tinyurl.com/keepoppo 03/08/2016 at 15:39

0

Ha thats really awesome. Yeah so a little USB cable, running to that relay, and then the +ve power to the fan running through the other side should work pretty nicely.

You might find it easier just buying a little pre-made board from Ebay . As far as I can work out from the ones I found, it looks like they need a +5v supply, a gnd connection and an input, so just jumping the +5v to the input would cause it to switch which would be nice and simple. So it would just be a case of hacking apart a USB cable and putting those wires in the right place, and hacking apart the power cable to the Fan, and viola.

Rusty Vandura - www.tinyurl.com/keepoppo > RWS Motorsport 03/08/2016 at 15:45

0

I would know where to begin with the circuit board idea.

Rusty Vandura - www.tinyurl.com/keepoppo > RWS Motorsport 03/08/2016 at 15:46

1

Thanks. That duct took me four hours to fabricate and one complete do-over.