# Digatal cell phone circuitry

#### Greenhorn

Joined Aug 30, 2005
1
Hello, I'm working on a home project that would alow me to turn lights off in my hunting cabin that has a 12 volt power system, (i can't aford a power co. line to this place so i implemented a 12 volt system). The system is charged by an alternator system driven by an engine that utilizes propane gas that has to be manually started.
Problem1) My kids use the cabin!!! They leave the lights on when they leave!!! I need to implement a cell phone system that i could call and shut the power off. My thought was to use an old phone (digital) and connect the ringer circiut to a solinoid that would accomindate 12 volts. I thought the solinoid would have to be "always on"and use the cell call to coil it off and then reset it or put it on a timer.
Problem(2) I took the phone apart and I was beaten. I need to know if my project goal is reachable and if someone can tell me how to set it up or guide me in the right direction.
SCOPE: I call the cell no. the phone rings at the cabin and the voltage from the ringer implements a 24 hour timer that turns off an always on solinoid that turns the power OFF!
Thanks, inadvance to anyone who can help. GREENHORN

#### Gorgon

Joined Aug 14, 2005
113
Originally posted by Greenhorn@Aug 30 2005, 01:05 PM
Hello, I'm working on a home project that would alow me to turn lights off in my hunting cabin that has a 12 volt power system, (i can't aford a power co. line to this place so i implemented a 12 volt system). The system is charged by an alternator system driven by an engine that utilizes propane gas that has to be manually started.
Problem1) My kids use the cabin!!! They leave the lights on when they leave!!! I need to implement a cell phone system that i could call and shut the power off. My thought was to use an old phone (digital) and connect the ringer circiut to a solinoid that would accomindate 12 volts. I thought the solinoid would have to be "always on"and use the cell call to coil it off and then reset it or put it on a timer.
Problem(2) I took the phone apart and I was beaten. I need to know if my project goal is reachable and if someone can tell me how to set it up or guide me in the right direction.
SCOPE: I call the cell no. the phone rings at the cabin and the voltage from the ringer implements a 24 hour timer that turns off an always on solinoid that turns the power OFF!
Thanks, inadvance to anyone who can help. GREENHORN
[post=10027]Quoted post[/post]​
Hi Greenhorn,
Do you really need to use a mobile phone to do this?

What if you install a cheap IR-detector on a central place in your cabin. You then use the output from this to restart a timer every time somebody walks past. So when everybody leaves the retrigger stops and the timer times out after some hours. The output from this timer release a selflatched relay that is your main power supply switch. When you arrive at the cabin, just press a button to activate the relay, the timer and the IR-detector. This way you don't draw any power from the battery when the power is off, and you will always know that the power is off.

This is not a very hi-tech solution, but it works every time, if you don't have big mice or rats in your cabin to retrigger the timer

TOK

#### nomurphy

Joined Aug 8, 2005
567
Place the phone in a sealed, non-metallic, foam box with a unidirectional mic duct taped at a proper angle to the phone and wired into a "sense" circuit. When the phone rings, the mic acts as a sensor to trip your switch.

I think Red Green would be proud of you.

#### mozikluv

Joined Jan 22, 2004
1,437
hi,

if you need a schem on a sound activated switch as what "nomurphy" suggested, just holler.

#### n9xv

Joined Jan 18, 2005
329
You can do this with any kind of "RF operated" remote controll. Their is a good resource at discovercircuits.com. You could use a pair of cheap CB walkie talkies to accomplish a simple carrier operated switch. If you want to get really fancy with it, youcan use a DTMF decoder board from an electronics hobby outlet etc and dial in various DTMF sequences to do different things.