help designing a remote power shut-off (lock out an appliance)

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icemachineman

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I'm not what you would call an electronics wizard, but I was wondering if someone could help me out with designing a remote control rf signal power shut-off control. Let me start out by explaining what I need it for. I manage a fleet of commercial ice machine / refrigeration rental equipment, and in today's economy we're having to disable these machines when customers don't pay their bill. Since one of our guys was attacked by a customer for shutting a machine down, we desparately need to remotely shut our machine s off. I purchased a remote shut-off on e-bay, but it doesn't stay in the "latched " position (like it's advertised) when we shut the power off to it, so I'm wondering if someone can steer me in the right direction with this. right now, if we wired this in, a customer can unplug, and plug the machine back in, and the machine will start back up.We are normally within 50 feet of the machine when we need to shut it off, however, there's places where we would probably be a couple hundred feet away.I really don't need something that goes much further than that, but is there something off the shelf that someone can recommend? if not, I guess I have to try and tie a latching relay to the remote module that i have now. I was going to post the link to that e-bay one i bought already, but I'm not sure if this site will let me put a link in here or not. I don't want to go against any rules.
It runs on 24 vdc, and on the module, when I click the remote, I'm simply breaking the main power leg that feeds the power to the main control board on the machine,thus making it completely dead.
my second project involves making a remote shut-off that can receive a page from a cell phone, or computer that will shut these off also. I would really rather not have to put these together from scratch, so if anyone knows where I can buy either of these off the shelf, that would help tremendously!
 
How about adding a "keep-alive" battery so that the logic in the existing module can retain its "logic-state" during a "power failure", actual or induced by momentarily unplugging the machine. If the logic in the module is CMOS, you could do this with a tiny battery. Wire it so the battery doesn't power the radio receiver, or the output relay and its driver; just the "logic".
 
Mike, I very much appreciate your help !
actually, we thought about doing that with a similar system from the back up flood lights on a exit sign. we were going to take the existing electronics out of it, and wire it into the shut-off module.There's a couple of reasons why I didn't want to do it this way: 1 - extra cost with large battery (added maintenance,etc) future replacement batteries, potential to get damaged,cust. finding it, and disconnecting,etc. 2. building it too complicated will also take up too much space.
If I use a small battery like you're saying, I'm afraid of how long it will last. Some of these machines will need to stay locked off for over a month or two in some cases. When they lock the doors to a business with our machine in it, it might be a few months easily.
I was told from some people with some electronic knowledge (enough to be dangerous) that if you get a "latching " relay, you will not need to do this, so that's why I'm trying to go in that direction.The battery option would be a last resort, but I do appreciate the input very much !
 
just so everyone can see what module I'm starting out with ( that is supposed to have a latching mode, but actually doesn't) I posted the link to the e-bay sales page. I'm not trying to advertise this, I simply want to post it, so everyone knows what I'm starting off with. If for some reason the link doesn't work, go to e-bay, and type in the item# 250541488239

**broken link removed**
 
one thought is to insert a fuse that the remote blows upon activation.
then when the customer pays their bill you replace the fuse.
A small normally open relay that is activated with your existing remote.
relay is placed after the fuse. the contacts are connected from the netural line to one of the hot leads (a 3 wire 220). contacts close and blewly the fuse is blowen and the machine no workie.. Just be sure the fuse is able to handle the normal amperage. it may damage the relay as well?
Another option is use the normally open relay that your remote closes upon activation. customer dosn't pay their bill the remote deactivates the relay and machine won't run until reactivated. Post a link to your remote.
 
A radio control that works for me in my home is an X10 "transceiver" (receives RF, retransmits on the power line). You don't need the retransmit part, but the module has a relay built in. It's a latching relay, so it remembers through power interruptions.

There's absolutely no security, so if the customer figures out you're using X10, he'll be able to just get his own transmitter. It's RF, so an all-metal machine might shield it. My "transceiver" is **broken link removed**, about $13. The "Slimfire remote" might be a nice transmitter for about $20.

Note that range and reliability are highly dependent on the environment.
 
A 3V coin-cell (CR2015 type) will keep a CMOS flip-flop powered (and retain the state) for about 10 years.
 


Contact rkn.bits@gmail.com with proper requirement details...
 
second thoughts

after rethinking my last post there are several problems.
one you would use two fuses for each hot wire on a 220 system.
assuming these machines use water, just disable the water solenoid which is more than likely 110v.
inserting a cmos flip flop circuit is not to bad of an idea but then you would need a power supply etc.
most machines these days use solderless connectors on there internal wiring (ease of assembly line ) thus inserting a disabling component is not really hard.
For protection of what ever device you install internally, I suggest getting some labels that stick on over the access hatch or ?.

NO SERVICEABLE PARTS BEYOND THIS POINT
REMOVAL OR BREAKING OF THIS SEAL WILL CONSTITUTE TRESPASSING THUS A $10,000 FINE WILL BE IMPOSED

when I lived is S. Cal the electric company offered a discount on your electric bill if you had them install a disabling device on your air conditioning unit.
during periods of peak power requirements, the electric company just signals your air conditioner to shut off. so such a device is available but ??
 
just saw the link to iteem your using
it has no power supply!!
I assume you need to buy a plug in wal wart power supply?
just unplug the wal wart and the customer has disabled your disabling device.
you need to put all inside of machine (see my privious post)
 
been burning he brain cells thinkng

about this application
FIRST - why did you purchase a 6 channel receiver? you only need one per appliance.
seeing how the receiver is connected to power as is the appliance, everytime the customer unplugs the appliance the receiver is reset as well thus disabeling the receiver.
A cmos D flp flop would maybe work (unpluging then pluging back in may clock the D flip flop thus enabling the appliance. I may be missing somethig here but ??
My thoughts again (revised)
insert a fuse (110v line) to the water solnoid along with a relay, resistor.
relay controled by receiver. normally closed relay opens to disable unit and fuse is blowen so all the pluging and unpluging won' have any effect.
will draw schematic.
 
maybe way off in left field ??

here is a viable solution but every time you disable a machine you need to make a service call to replace the fuse.
the 15 ohm resistor is to prevent a direct short.
2 watt resistor should?? be big enough because the fuse should blow immediately anyway.
you just need to find out how mush current the water solenoid draws.
same idea could be employed for entire machine if its 110v. not suggested.
 

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i can solve ur problom.pl con...Yahoo!
 
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