Trip a 5 volt relay using a frs radio

Ya’akov

Joined Jan 27, 2019
5,508
Even with the bike off and the low power the remote I have is lacking on range. Still have to be right on top of antenna to activate it. I was thinking the receiver need the full 12 volts to work well.
Maybe it does, but the current requirements are very low, so you might be able to simply use a boost converter to raise the voltage and operate it.
 

wayneh

Joined Sep 9, 2010
17,166
Remote.control is not a permitted use in the FRS service.
I didn't know that but it makes perfect sense now that you say it. It would be a huge annoyance to crowd the air with nuisance noises and ongoing data traffic. The proposed use wouldn't comply with the letter of the law but with the spirit of it – a remote shutdown is a brief and presumably 'rare' event.

But as I speculated, there are better solutions. I like the idea of off-the-shelf RC gear. Get a used RC set off eBay and hack it.
 

MrSoftware

Joined Oct 29, 2013
2,027
The voltage of the receiver won't have much to do with how well it works, but the receiver technology and quality will have a lot to do with it. Transmitter is where the power matters, and antennas are very important, arguably more important than power. If budget is no object then UHF might get you the best range, but will definitely be spendy. The receiver antenna needs to be out in the open, not blocked by metal if possible and not blocked by the fuel tank, as liquid is excellent for blocking RF. If you could get something like this, cut it down to appropriate size and attach it to the rear swingarm or rear fender, then mount the antenna to the top of it. Get the antenna a foot or two above the riders head, that should help a ton with range from all directions. You could even make the whole module fit into a box mounted to the rear fender, run the antenna up that pole, then the only thing mounted up closer to the motor is the actual relay.
 

Ya’akov

Joined Jan 27, 2019
5,508
The voltage of the receiver won't have much to do with how well it works, but the receiver technology and quality will have a lot to do with it. Transmitter is where the power matters, and antennas are very important, arguably more important than power. If budget is no object then UHF might get you the best range, but will definitely be spendy. The receiver antenna needs to be out in the open, not blocked by metal if possible and not blocked by the fuel tank, as liquid is excellent for blocking RF. If you could get something like this, cut it down to appropriate size and attach it to the rear swingarm or rear fender, then mount the antenna to the top of it. Get the antenna a foot or two above the riders head, that should help a ton with range from all directions. You could even make the whole module fit into a box mounted to the rear fender, run the antenna up that pole, then the only thing mounted up closer to the motor is the actual relay.
The small board I linked uses 433Mhz. Improving the receiver antenna would definitely help. Even a nice 1/4λ whip on a fender or frame would probably do it.
 

Ya’akov

Joined Jan 27, 2019
5,508
I didn't know that but it makes perfect sense now that you say it. It would be a huge annoyance to crowd the air with nuisance noises and ongoing data traffic. The proposed use wouldn't comply with the letter of the law but with the spirit of it – a remote shutdown is a brief and presumably 'rare' event.

But as I speculated, there are better solutions. I like the idea of off-the-shelf RC gear. Get a used RC set off eBay and hack it.
FRS is probably second only to GMRS as the most abused service in the US. FRS is not supposed to be used for commercial purposes but it is everywhere. GMRS is a licensed service but the wide availability of cheap FRS/GMRS combo transceivers means it get used without licenses or operating rules everywhere. It's a shame.
 

Ya’akov

Joined Jan 27, 2019
5,508
So I bought this and got it today... any idea how or where to hook the learning button which I don’t have... instructions are very vague
Power to the plus and minus terminals, the other two are the relay. It is normally open, so if the power fails to the board, it should open. The "latched" mode should work for you. It will close on one button and open on the other.
 

Ya’akov

Joined Jan 27, 2019
5,508
I have to run out and do some things, but I will be back in a bit if you need more help. I think that should do it for you though.
 

Thread Starter

James Millett

Joined Apr 4, 2019
10
Yeah if you could help further her that’ll be great.. i guess to need to program the unit. Says connect the learning button but doesn’t say where to hook it and it didn’t come with one.. I image I’m supposed to jump a connector somewhere? This is obviously why I’m a truck driver lol
 

Ya’akov

Joined Jan 27, 2019
5,508
Yeah if you could help further her that’ll be great.. i guess to need to program the unit. Says connect the learning button but doesn’t say where to hook it and it didn’t come with one.. I image I’m supposed to jump a connector somewhere? This is obviously why I’m a truck driver lol
Here's a photo from the Amazon listing.

upload_2019-4-7_14-7-33.png
 

MrSoftware

Joined Oct 29, 2013
2,027
Taking a guess; to learn the transmitter, power the module with 12V. When it says "connect the learn button", I believe it means to short the 2 pins that are marked "set". I'm not clear if you keep it shorted, or short it briefly so maybe try both ways. Then press the A button on the remote and watch for the LED on the receiver to flash. Repeat for the B button on the remote. I believe this should learn the remote.
 
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