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 Post subject: DTMF remote control
PostPosted: Sat May 26, 2018 7:55 am 
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Posting this under Self-Sufficient Living since it's DIY related, although maybe under Communications makes more sense?

Anyway, stumbled across this little item the other day and now have two on order. It's an inexpensive DTMF decoder that runs off 12v and can operate 4 programmable (toggle, latch, delay, etc) relays. The first thing I'll be testing it with is to remotely enable/disable my homebrew burglar alarm in our "back forty" polebarn, currently I'm setting the alarm off each time I enter and have to turn it back on when I leave, so being able to disarm it before entering by sending a DTMF tone, or re-arming it from the house (400 yards away) if I forgot to turn it back on will be convenient.

Instead of using it with a cellphone I'll attach a HT to act as the receiver, and power the HT radio and the DTMF decoder off the same 12v (tiny solar power setup in the barn) supply that runs the burglar alarm now. Basically, set the DTMF relay up for toggle mode, and run the power for the burglar alarm through the 'normally closed' contact on one relay so it's always on. Then when I want to disable the alarm I send the DTMF tone from another radio and it opens the contact removing power from the alarm system. To re-arm it, send the same tone and it toggles back to the normally closed position.

This is as much a proof of concept test as it is a final solution for a remotely controlled burglar alarm. But that it runs off 12v, has a much greater range than a Part 15 wireless keyfob-type remote control when used with a HT and external antenna, and doesn't require any working telecomm/cell tower infrastructure to function would seem to make it a great solution for anything you might want to remotely control in a griddown situation. In fact it you might call it a solution in search of a problem, which is really the point of this post.

Any thoughts on applications for this in a griddown or ZPAW scenario? Bonus points for home/retreat defense applications, within the forum rules of course. The manual (http://www.einausschalten.com/0057522-y.pdf) shows an example of wiring it to motor to control forward/reverse direction as one example, and I'm thinking remote illumination (visible or IR light) might have some uses.


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 Post subject: Re: DTMF remote control
PostPosted: Sun Jun 03, 2018 10:19 am 
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No ingenious suggestions yet? :cry:

Anywho, they arrived yesterday and been playing with one. Just bench testing so far, luckily I had a 2.5mm to 3.5mm audio cable as the headphone jack on the Baofeng is 2.5mm but the DTMF decoder jack is 3.5mm. The decoder did come with a 3.5mm to 3.5mm cable.

Fits perfectly in a Altoids tin. Connected to a 12v battery to power the DTMF decoder and an auto lamp (just for testing purposes). This shows the overall setup with only the single power LED lit on the decoder:

Image

The default config for the decoder is to momentarily close (1 second) the relay when the corresponding DTMF signal is received, this wasn't what I wanted so I changed the mode to "toggle" so the relay stays latched (open or closed) by soldering the "M0" pad closed. With the auto lamp connected to relay #4, sent a DTMF "4" from a different radio and the relay closes and stays closed until another "4" is sent:

Image

Next will be wiring this into my motion sensor alarm to remotely activate/deactivate it. Have a 12vdc flood lamp *somewhere* that I may connect on one of the other relays for outside lighting around the polebarn. Another possibility I've been thinking about is the ability to remote start my Honda EM5000 generator, we bought the remote start kit for it but rarely used it. When the battery on it died I never replaced it as the gennie never takes more than 3 pulls to start anyway.

Found the programming guide for the decoder as well, if anyone wants the link or the files just let me know. Each relay can be set to a 1-4 digit DTMF code, programming is done via DTMF signals and is very easy, and the programming is saved on power up/down.


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 Post subject: Re: DTMF remote control
PostPosted: Sun Jun 10, 2018 8:32 am 
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C'mon people!

Image

Field installation and testing yesterday, this is nerdly cool stuff lol. Baofeng UV-5RA as the receiver, with a battery eliminator and wired to the 2 group U1 batteries in my tiny solar system for power. Just using the standard rubber duck antenna on the Baofeng and it's mounted about 10' high on the inside of a metal pole barn but works (ie, receives) when a tone is sent from another HT from at least a couple hundred yards away. Need to add an external antenna at some point for greater receive range.

The relays work and have so far proven reliable, important since there's no positive confirmation from outside the building that the alarm was turned off or on after the tone is sent. Had some early failures when I had the volume on the Baofeng turned up to about 80% (overdriving?), but found the controller seems to like the Baofeng volume to be closer to about 25%.

Attached an old "bargain bin" 12v spotlight to one of the other relays on the controller board and mounted it under the eaves of the barn to light the driveway. The final test last evening was to roll up in the truck, turn on the spot lamp and turn off the alarm before exiting the vehicle, feign retrieving an item from inside the pole barn, then reverse the process as I left.

So next is the external antenna, thinking of building a dual band J-pole and mounting it at the barn peak which should improve the range some. Before winter will likely need to upgrade my solar panel, currently it's just a 10w model which provides something close to 3 amp hours a day, which is about exactly what the Baofeng (75mA), the DTMF controller (13mA), and the motion sensor (WAG of 50mA) consume in a day when just in "standby" mode with no other loads. Done right I should probably upgrade the batteries and the charge controller as well, the solar system's original purpose was just for powering the motion detector and occasional cell phone/radio charging but is undersized now. And guess I'll find out how long a UV-5R will last when left powered on 24X7 in temps ranging from -20 to 90 degrees...


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 Post subject: Re: DTMF remote control
PostPosted: Sun Jun 10, 2018 9:03 am 
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Just so I am following you are using your HT to control and read your remote alarm system in your barn.

I don't have much but here are my thoughts.

This is a good idea as a lot of thefts occur in barns and almost no one puts an alarm system out there. I have a couple of camera looking at the barn and shop but nothing reactive if people get in to them other than some motion powered flood lights.

If your system is eating all your solar generation on an average day you definitely want to upgrade that. Such low wattage though, so a 15w panel can be had for $40 or even less, should provide everything you need.


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So next is the external antenna, thinking of building a dual band J-pole and mounting it at the barn peak which should improve the range some.


Just be careful there and ground it properly. You don't want a lightning strike.

I do have a question on your motion sensor. I get animals in the barn frequently (cats, mice, possum, birds etc) some of these set off the motion lights. I was able to direct the lights sensor to about chest high but this does not stop the birds from setting it off. How do check on false alarms?

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 Post subject: Re: DTMF remote control
PostPosted: Tue Jun 12, 2018 5:50 am 
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Stercutus wrote:
If your system is eating all your solar generation on an average day you definitely want to upgrade that. Such low wattage though, so a 15w panel can be had for $40 or even less, should provide everything you need.


We have a larger solar system at the house which is almost 12 years old now, the plan once I need to replace the batteries here is to take the two best old ones and relocate them to the barn along with a larger (130w or better) panel. That might be a couple years away however, so yea, need to install a larger panel in the interim. Checked the voltage on the ones at the barn yesterday (during the day, so under charge) and reading 13.6v, so looks like that little 10w panel can keep up with the standby power requirements at least.

Stercutus wrote:

I do have a question on your motion sensor. I get animals in the barn frequently (cats, mice, possum, birds etc) some of these set off the motion lights. I was able to direct the lights sensor to about chest high but this does not stop the birds from setting it off. How do check on false alarms?


We use a Dakota Alert (with the range setting on "low") and have only had 3 false alarms in about 5 years time. Height is the same as yours. Spiders were the cause I think. I modified the Dakota Alert to also power a car horn (at the barn) when it detects motion, added that after responding to a false alarm one night and deciding that silent alarms, surprised criminals, armed homeowners, and lots of adrenaline could have deadly consequences that just wasn't necessary. Better if they're gone when I get there.

Still thinking about remote start/stop of the generator... would require two relays I think. One to control the "run/stop" toggle switch and another momentary contact for the "start" button. This has little practical purpose I can think of other than the "gee-whiz" factor, but I'm good with that. Hmmm, suppose I could leave a battery charger plugged into the generator so it automatically starts charging the batteries that are being constantly drained by virtue of having the ability to remotely start the generator :lol:. Still trying to come up with other uses (like I said, this could be a solution in search of a problem), maybe a DTMF controlled automatic gate opener...


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