Hello !!! Can you help me
.I need an electrical circuit for remote control by cellular phone
I Have a small car and I want to do I manage the movement of the car, through mobile
Are there ideas
??????????????
Each key in the cellular telephone issued different tone. Can we convert it to orders
??????????????
Yep,
there was an artical in 'Electronics For You' magazine two moths back about this.
the idea is like this: two cellphones to be used, one as transmitter and another as receiver. the receiver cellphone to be fitted on the small car you want to control. Connect head-set with the receiver phone and keep the phone in Hands-free mode so that you don't have to press a button to receive a call.
Cut the speaker of the head-set and connect the leads to DTMF decoder (say, MT8870). Interface this DTMF decoder to microcontroller for reading the decoded data.
now, whenever you dial a number to the cellphone fitted on the car, and once the call is accepted, you can press keys on your transmitting cellphone. A DTMF code of the key pressed is sent to receiver cellphone and the code (a 'tone') flows to the head-set connected to it. The DTMF decoder will decode this tone and send the code of the key pressed to microcontroller.
You can program the microcontroller to take whatever action you want based on the received key-code!!
This kind of project does crop up from time to time and was wondering if a PIC could be used instead?
I'm not up to speed on these devices but from what I understand they have a number of I/O lines. Therefore it could detect the phone ringing and answer the call, but could one of these digital i/o port lines be connected to the loudspeaker and decode tones?
Am almost sure cellular telephones do not emit DTMF tones. Do they? I do not have one to confirm.
If so, call would have to originate from landline for your circuit to work.
to remotely control just one action to be taken it suffices if the second telephone is activated either by silent call and answer or just the normal way.
You might activate the circuit from the ringer of the telephone. That way you won't require a DTMF decoder which anyway makes sense only if a dial tone is transmitted.
The described method is used in southern Thailand by islamic terrorists to remotely have bombs detonated.