Welcome to this page on how to build your own DTMF devise with built in Transponder ready programmed into the Microcontroler.

If you would like to see the DTMF devise working and sending back a Morse code when the relay has switched on or off then visit my You Tube video here.

1). In the photo above is a DTMF devise that will let you know it has switched on a relay or what ever is connected to the header pins by sending you a Morse code signal one type for on and one type for off.

2). The little green circuit is the DTMF decoder with hex file all ready programmed into it the green circuit is ready built and tested all you need to do is solder  the header pins in as well as the trim pot.

3). Please note this set up and pin out connection is for the Nokia mobile phone 1208 more phones will work but I have only tested it with the Nokia 1208 mobile phone with the transponder turned on.

4). The transponder are the tones you can here on the video when the relay's switch on or off it will send a signal back to you the devise can be used with Cell phones, Ham radio or any form of communication devise.

(Now we will look at the parts you will need to build your own devise and how to set it up)

5). The first item will be the SMT Decoder you can buy this from the makers of the DTMF devise CS-Tech order the DTMF Decoder from here. If you like you can buy a ready built devise ready to go from the same page this is useful if you do not understand electronics.

6). You will need one Nokia mobile phone 1208 model you can buy them in most shops or on Ebay in your own country.

7). The SMT DTMF Decoder comes with a 4 pin jack plug with the ready assembled devise above we will look at how to wire it up on the next page.


8). You will need some Matrix Board without copper strips size 127 x 95mm you can get this from any electronic shops or order it from bits box they do ship international to order it Click here.
terminal block


9). You will need six 2-way PCB mount terminal connector 5mm pin pitch. order this from bits box here for both 2 & 3 way connecter blocks Click here.

10). You will need one 3-way PCB mount terminal block. 

relay diagram

11). You will need six relays at 12 volts you can use DPDT Mains Power Relay Contacts rated 8A/230Vac, 8A/30Vdc. 12Vdc coil 360R order them from bits box Click here:

red 5mm led

12). One 5mm Red LED you can get them from any electronic shops or on Ebay or you can order them from bits box Click here. 


13). You will need two 1K Ohms resisters order them from bits box Click here.

Now on the next page we will look at setting every thing up to get our project working.