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Mobile/Cell to switch on PC

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fingers88

New Member
Hi first time poster so here goes.

First of all I searched the forum for something similar but couldn't find an answer/solution.

Lets just say I know NOTHING about electronics and start form there, straight forward project I'd like to be able to switch on my home PC by calling/SMS. The idea is I have a spare mobile phone, and I'd like to be able to call the spare phone which in turn switches on my PC.

I have given it some thought and my initial idea is to use a LDR facing the mobile that will activate a solenoid that will push the power button. Knowing nothing about electronics I have seen a basic kit on ebay which an LDR lights up an LED when it detects light. So I'd make a box which the completed PCB sits in and the phone facing it ready for me to call. What I'm unsure about is instead of it lighting the LED can the 'closing' of the circuit be used to switch on a solenoid?

That's the basic idea but I know there's a lot to it for someone with no electronic knowledge.

Other things I think I may need to consider is a relay so the battery can power the solenoid when the light sensor circuit closes, the solenoid should be straight forward, a push action with a spring return. Not too sure about the battery power needed for the whole thing.

One other thing is when the phone 'rings' I only want the push button action to push once for about 1 second only. When the phone rings it lights up for a few seconds and if the button is pressed for that long my PC will switch off.

OK so that's it, I'm welcome to other more simpler solutions that will do what I want. Please remember I know nothing about electronics so nothing too technical just yet.

Many many thanks.
 

Diver300

Well-Known Member
Most Helpful Member
Firstly, I guess that if you want to turn on your PC, you have a broadband connection for it to work with.

If that is the case, you might be able to make the PC wake on LAN activity.

Wake-on-LAN - Wikipedia, the free encyclopedia

You would need either VPN, or a dynamic DNS account to route the signal to the correct place. A fixed ip address on the computer would be needed.

If you want to have a mobile phone turn on the PC, a small relay connected instead of the vibrator motor is one way of doing it.
 

fingers88

New Member
Firstly, I guess that if you want to turn on your PC, you have a broadband connection for it to work with.

If that is the case, you might be able to make the PC wake on LAN activity.

Wake-on-LAN - Wikipedia, the free encyclopedia

You would need either VPN, or a dynamic DNS account to route the signal to the correct place. A fixed ip address on the computer would be needed.

If you want to have a mobile phone turn on the PC, a small relay connected instead of the vibrator motor is one way of doing it.

Thanks for the being the first to answer, I was begining to think what I wanted wasn't worth a response. I do have the internet connected to the computer but that was so I could control it via remote desktop.

I don't want to open up the phone I want to stick to the method of the phone lighting up when rung to trigger a LRD, also I'd rather the 'trigger' physically push a button not short the power pins on the motherboard. That way I could attach it to any computer/device. I have a basic circuit diagram that I'll upload and see if somone can complete it somehow.
 

fingers88

New Member
Ok here's a diagram I got from the interent which shows what I think is what I need. The diagram shows a LED, but I'd like to know if I can simple connect a solenoid where the LED is so it pushes the button?

I take it I'd need a 9v solenoid? Will there be an issue with replacing the LED with the solenoid?

I only want the solenoid to push once then retract but the phone stays lit for a good few seconds. I'll need something that only activates the solenoid for a second the first time it rings then ignore the phone light after that.

Anyway I hope someone can help.
 

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Diver300

Well-Known Member
Most Helpful Member
You should connect the solenoid to the collector of the transistor, not the emitter. That way it will turn on and off completely. The circuit you have drawn will have the solenoid partly on, and the transistor will get hot.

I don't see why you wouldn't want to connect to the motherboard. All modern PCs with ATX power supplies have low voltage on-off switches, and the switch plugs into the motherboard. There is no danger to yourself or the motherboard.
 

fingers88

New Member
Thanks again for the response and the solution. Is this what you mean?? I take it everything else is in the diagram is still needed. The diagram I got from youtube and from what I can remember the LED stay lit for as long as there's a light on the LDR. I only want it to trigger once so I'm guessing I'd need something else to do that?

I will try it connected straight to the motherboard. I don't have an issue with it but like I said I like the option of it activating something else. I have a NAS which would be another device I'd like to turn on remotely.

This may seem like a daft question, but with the new setup is the voltage from the transistor 9v? I'd have to look for a solenoid with that power rating.
 

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    circuit diagram 02.JPG
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