Could anybody help me bout my project...its an on/off controller of appliances by using the phone...it uses a dtmf!! i got this circuit but im not sure it would work! :cry: could anyone please assess my diagram! i dnt knw also how could i be able to monitor when the relays are on or off...my professor required this feature together with an input security code before u could access the device!! :? im not sure if the device will lift the phone up when there is a call!!! The main part...which is the DTMF to BCD Decoder (KT3170) is also not available in our country (Philippines)...where could i get this IC!???? PLEASE HELP!!! :cry: thank you!!!!
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Try search for MT8870 from Zarlink Semiconductor.
This circuit work, when in Your country possible DTMF sending while the phone ringing (in Europe not working). Anyway, You can to build a ring detector with optocoupler for off-hook function and use the asterisk output for on-hook.

tele remote control...
DTMF is one of the essential components for teleremote control. It dedode up to 16 analog tones to 16 digit signals. Even there are only 12 keys on the phone but some phones can have upto 16 keypads. The KT3170 is almost the same as MT8870. The MT8870 is very popular i think, cause i bought it easily.

Just go through infidget (my project) you will stop your project.

This article should help you a lot in what you are looking for i think. It decodes the DTMF signals produced by the telephone lines using the DTMF decoder (8870) and then feeds it to the PIC16FXX microcontroller that uses it to turn the devices on and off after entering a correct password.

Regards.

Originally Posted by dramrattan

This article should help you a lot in what you are looking for i think. It decodes the DTMF signals produced by the telephone lines using the DTMF decoder (8870) and then feeds it to the PIC16FXX microcontroller that uses it to turn the devices on and off after entering a correct password.

Regards.

how does one connect the controlled device to the relay Driver?

for example if i want to control, say air con or a Computer, what wires do i connect to the relay driver?

Originally Posted by dramrattan

This article should help you a lot in what you are looking for i think. It decodes the DTMF signals produced by the telephone lines using the DTMF decoder (8870) and then feeds it to the PIC16FXX microcontroller that uses it to turn the devices on and off after entering a correct password.

Regards.

how does one connect the controlled device to the relay Driver?

If I want to control, say air con or a Computer, what wires do i connect to the relay driver?