Posted: 1/19/2012 7:58:21 AM EDT
I am asking this here, because I know you are some of the most knowledgeable guys I know...
Is there an off the shelf receiver that can decode DTMF tones to operate a relay. I am wanting to possible control lights in my shop and/or house using DTFM tones from my HT, but I don't want just any stray RF to activate and wanted to use maybe a 8 or more digit DTFM broadcasted from my HT to activate a relay. Any ideas? Cheap is the keyword here. |
Yep its doable 
Here you go.... Link to Hack a day Link to authors page You say you don't want interference? My idea was to use pl tones. I was doing some tests with two HT's (ok it wasn't a test) same freq one with a tone one without a tone. even with the radios a few inches a part there was no interference. I would set it up within 145.50-145.80 Miscellaneous and experimental modes or 223.64-223.70 Links, control or 445.00-447.00 Shared by auxiliary and control links, repeaters and simplex (local option) <<Taken from ARRL |
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http://www.motron.com/product_info.php/products_id/105
Receivers with DTMF decode built in don't seem to be as common as they were in the 80s. I had a couple HTs with DTMF squelch that would be trivial to use as a remote control. The device above is often used with repeaters to turn things on/off. It supports long sequences of digits to control things as well. |
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Quoted:
http://www.motron.com/product_info.php/products_id/105 Receivers with DTMF decode built in don't seem to be as common as they were in the 80s. I had a couple HTs with DTMF squelch that would be trivial to use as a remote control. The device above is often used with repeaters to turn things on/off. It supports long sequences of digits to control things as well. I like that. I am looking for something like this, but with maybe the reciever built in. Does that animal exist as a descent pricepoint? |
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Not really. The radios that had DTMF built in used it for squelch, and would only do a single channel if you
did a simple hack (audio out switching a transistor or something.) I'd suggest a DTMF relay unit like I linked, and then a cheap VHF receiver –– a basic 10-channel scanner would work fine and could be had used for probably $10-$20, and new for under $100. Something like a Uniden Bearcat BC72XLT would work fine. |
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What Seek2 said. Just use the cheapest scanner you can buy. There are a gazillion little DTMF decoder boards, too many to list here. Just google "DTMF decoder".
Some have a very cool feature that, if installed in a radio, will cause the radio to acknowledge the command by transmitting a beep back at you to confirm receipt of the command. |
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Remote control is a favorite subject to me and there have been a lot of good ideas expressed here.
Here's mine... 
For control by DTMF with your ham talkie and relatively secure. To get something up and running QUICKLY that has a small power draw and uses off the shelf 'modules' in a compact system, I'd suggest picking up a $46 Baofang, set the sq to '0' [open] and to the frequency of your choice... Get a compatable cable [a cloning or mike cable] to interface it to... ... an NHRC-Remote+ control... ...and be done with the fussing around. 
Cost can be less than $100 if you build up the NHRC kit, but I'd suggest just getting a built one to save time. The neat thing abt the NHRC remote controller is that it has SO MANY features all ready to put to work... ...and one of the best is it can reply to your commands if to use a tranceiver instead of just a receiver [like a pager, etc]. The NHRC has the abilty to even ID your transmitted signal IIRC. To me this is by far the simplist and quickest solution with the most powerful capabilities, if there aren't other special constraints. I'd love to hear a better solution with equivalent capabilities. 
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Quoted:
Remote control is a favorite subject to me and there have been a lot of good ideas expressed here. Here's mine...
For control by DTMF with your ham talkie and relatively secure. To get something up and running QUICKLY that has a small power draw and uses off the shelf 'modules' in a compact system, I'd suggest picking up a $46 Baofang, set the sq to '0' [open] and to the frequency of your choice... Get a compatable cable [a cloning or mike cable] to interface it to... ... an NHRC-Remote+ control... ...and be done with the fussing around.
Cost can be less than $100 if you build up the NHRC kit, but I'd suggest just getting a built one to save time. The neat thing abt the NHRC remote controller is that it has SO MANY features all ready to put to work... ...and one of the best is it can reply to your commands if to use a tranceiver instead of just a receiver [like a pager, etc]. The NHRC has the abilty to even ID your transmitted signal IIRC. To me this is by far the simplist and quickest solution with the most powerful capabilities, if there aren't other special constraints. I'd love to hear a better solution with equivalent capabilities.
That looks like the fastest, easiest way. and could be done for around $100 |
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Don't overlook that with the NHRC remote control, the unit can reply back to your radio with the status of what you commanded or some other info, I'd have to look.
It's actually similar to their mini repeater board. So a small solar panel, a cheap charge controller, an ATV battery, or say a Dewalt lithium battery, and your controller and radio and you could be all set for a self contained remotely located control free of the grid. If you want to get power consumption REALLY way down, then take an older pager and cause it to fire an electronic 12 vdc time delay relay, and turn on the big iron [kidding, the Baofang, whatever, and your DTMF decoder] and hold it on for say 5 minutes and then let thathigher power consumption stuff go back to sleep [off]. The pagers like the old Motorolas only draw 6ma at 3 vdc or in that ballpark. |
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If it were me I would use a cheap HT or even base. Like I said before, depending what you are using it for you may not want an accidental DTMF signal by using a HT you would be able to set it to a RX tone Yes, you could use a PL tone to break the sq and then send a DTMF tone set for really high security. |
This is what I am trying to do-my wife drives up to the house, keys up the HT on 147.445Mhz, type in 8675309, and has the porch light come on for her. Could be the shop lights, or open a gate, or turn on the xmas lights around the trailer that my redneck ass refuses to take down , or remote initiation of the claymores out by the mailbox . I have thought about using the circuitry for a garage door opener. Digital and encoded..fairly fool-proof. Thought about pagers...too damn hard to figure out how to trip a relay dependent on the message received as opposed to a general ON/OFF if a page is received...
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If you want to try a little bit more of a homebrew method look here:
https://www.hamtronics.com/ |