Turning on my computer with a cellphone as a trigger

Hello everyone,

Very excited to enter this forum as all my life i've been electronics enthusiast and for a long time it was my work.
I dont know if i am posting this in the correct forum so forgive me....

I want to make this small project that when i call a cellphone my computer will turn on.
here is what i have :
1. I have an older cellphone (with a number ofcourse) that i've removed its speaker (that rings when there is incomming call) and soldered it wires.
2. Simple relay 12vdc activation
3. 12VDC transformer (from 110vac to 12vdc)

i've attached a silly/starter diagram that i made and i need help "filling in the blanks".
the bottom right is the final output towards the computer which is obvious.

i looked it up online "cellphone trigger" and i found few things. mostly using Transistor....
funny thing is, in my line of work i never had to know/use/work with transistors... but i basicaly know what it is.

if i do need to use a transistor, could you tell me which one?

ofcourse i'm looking for the simplest way. can anyone asisst me?

Thanks for any responses

the ringer output will be ac or some modulated wave form. if you connect the relay to it it will chatter. you need to use a 555 timer as a mono-shot, or even a Flip-flop which will generate a constant high pulse when your cell phone rings. this output can then be used to drive a relay which in turn can turn on your ATX power switch.

hock

what if the speaker beeps for a 'Low Battery' warning..?

It may have been better to leave the phone as it was, and just have a mic and amp/integrator with a time constant to operate a relay after a certain ringtone length. I am sure googling will find plenty circuits. Also if you leave the computer plugged in, you will just need to switch across the power button to start, pressing again will shut down if you have it set up right.

Hi,
I already made a land rover using a mobile phone. I use 8870 dtmf decoder to control its various operations. So with a good design, you can turn on and turn off your computer and its accessories.
We can get 12 keys to control a Computer. It is too better.
With a micro controller, you can complete customize your PC.

i had planned to use power supply to vibrator as trigger for switching on a landrover.
i assume vibrator supply is greater in voltage and current than that to speaker. please correct me if am wrong.
i could not apply that into my landrover, but if you do please notify of yor experience in this post.

regards!
himanshu

wow, thanks for all the replys,
i'll answer on each one
1. hock - the sound output will be the speaker output just as it is, yes i understand what you mean by chetter but all i need is 1 click and the computer will turn on. if it will continu to chatter , thats ok.
i don't know what a flipflop is, i mean i know its a chip, but how to use it in my diagram?

2. cameo_2007 - low battery warning will not occure as this will be plugged into the charger constantly. because this cellphone will always be near the computer as it will be connected to it.

3. GrandAlf - yes i've googled that a bit, and also light sensor - because the backlight will turn on when there will be an iincomming call.
but as i mentioned... i'm not too familure with components beyond resistor / capacitor , AC DC , relays , soldering, multimeter, basic things.
yes i am eager to learn , i'll be happy for more in-depth guidence.

4. sarath.electro - i have no idea what your talking about... but i'll google it !

5-himrwt - yes, i've seen that option on google, it seems that it should give out 1.3 VDC, yes much more then the speaker voltage but the cellphone i dedicated for this job does not have a vibrator, its an older model. but if and when i'll get this thing to work... i'll let you know

any more suggestions?

Not sure of what country you are in, but if you not too confident about building stuff there are many kit manufactures that do sound to relay output in kit form. Sometimes known as clap switches, you can generally set the sensitivity so they do not respond to ambient noise. Maybe worth a search. Vellerman and Maplins spring to mind.