Review: An Inexpensive Wireless Relay

As you know, I’m all for DIY projects.  But sometimes, I’ve got to say, it’s just easier/better/cheaper to buy things.  For instance, let’s say you need the ability to remotely activate/power/E-stop a project you’re working on.  There are literally hundreds of ways you might accomplish this.  The wireless product offerings from SparkFun are quite extensive, and a very simple transmitter/receiver pair can be had for less than a five spot.  But don’t forget, you’ve still got to generate the appropriate signals to the transmitter, and then process those signals at the receiver.  Plus, you’ll want to add a couple of buttons, a relay/MOSFET, perhaps an LED, and of course a case.  By the time all’s said and done, you’ve spent three or four times your initial budget, not to mention all the hours consumed.  Now granted, if you’ve never done something like this before, it’s a great learning experience.  Seriously, if that’s the case, by all means, go for it.  But if your not interested in the experience, why not give this a shot:

Logisys RM01/RM02 Wireless Relay

This is the Logisys RM01/RM02 wireless relay.  It operates from a 12V source, such as a car battery.  The RM01’s relay can handle up to 6 amps and costs just $15.99 at Amazon.  The Logisys RM02 can take 15 amps and sells for $18.99 at Amazon.  I’ve recently purchased the RM01 for a project that has since been cancelled.  However, I’ve still gone ahead and done a little testing.  Here are the key points:

  • In the off state, the RM01 will draw 7.4mA from a source ranging from 8V to 15V (which leads me to believe it’s using a simple linear regulator).
  • When turned on, the RM01 itself will draw between 36 and 64mA as its supply voltage ranges from 8 to 15V respectively (so its coil resistance is about 280Ω).
  • The relay will not fully close until the input voltage exceeds 8.2V.
  • Indoor range (worst-case) with a 12V supply is about 30′ to turn on, 20′ to turn off (I haven’t explored this odd difference, so I’m not sure why it happens).  Outdoor line-of-sight range is about three times that.

I’m pretty pleased with this little guy.  It’s fantastically simple to use, and the two fobs even have red LEDs which light when their buttons are pressed, to let you know that their batteries are still good.

Honestly, I’ve been looking for an excuse to purchase one of these for quite some time.  Ever since a college friend of mine used them to control the power to his self-balancing transporter, they’ve been on my wish list (along with a few other things):

So despite the fact that the project I was going to use them with is no longer proceeding, I’m still happy to have them.  If you have any questions or would like me to do any other testing with the RM01, feel free to leave a comment.