What relay for the BBB when controlling about 5V battery-circuit?

[Bodo Kaiser]

Hello,

I want to control a 5V battery-powered circuit through a relay.

I am quite unsure which will work with the BeagleBoneBlack and a simple GPIO input.

Are there any recommendations?

Best,

Bo

[pat....@gmail.com]

Hi!  It just so happens that my IEEE group here at BYU-Idaho are putting together a flight computer for a rocket and used this to deploy our recovery system:

http://www.ebay.com/itm/221292380580?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

I can upload a schematic later but the idea is to have a 9V battery power the transistor which is triggered from an I/O pin from the BBB.  This battery also supplies the current to switch the relay after the I/O pin is triggered.  If your current draw is low enough, a transistor would work, but the BBB GPI/O pins output 3.3 V or you could use a 5V output pin that the board supplies to get the 5V directly.  

[Cody Lacey]

I'm not completely sure what you are asking.  Are you wondering if the 3.3V from the Black is enough to switch the transistor?

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[Bodo Kaiser]

Hi,

solved the problem by using following circuit: http://electronics.stackexchange.com/questions/56093/how-to-use-a-3v-output-to-control-a-5v-relay (the second one - first did not work…)

I used a 500 Ohm resistence.

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[Cody Lacey]

I'm glad it works, but the second circuit uses a BJT not a N-Channel MOSFET.  If you are using the relay board from the ebay link it already comes with the N-Channel MOSFET you need for switching the relay with a 5V source.  So I'm confused as to why you would use a BJT circuit.  Just wondering?

[Bodo Kaiser]

Yes, the second circuit uses a BJT (forgot to mention). I tried the first one but did not come to success.

The N-MOSFET I used required a lot of power to get working and there where no alternatives available (do not want to buy this stuff online and wait a week).

Am 12.11.2013 um 16:09 schrieb Cody Lacey <co...@beagleboard.org>:

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[Cody Lacey]

Ok, good.  I was under the impression you already had the relay board from the link.

Good luck with your project.