A PICAXE-18M2 DTMF CONTROLLER
This project uses a MC145436 DTMF decoder chip. Audio to the controller board is according to this chips data sheet. If you have low level audio then you will have to amplify it. The PICAXE-18M2 chip uses 4 outputs to drive the MOSFETs directly and 4 outputs to drive 2N2222A transistors that drive the 4 small 12 volt DC relays. Any of the relays or MOSFETs can be turned on or off. More then one relay can be on at any time. But only one relay or MOSFET can be designated as the PTT relay. If a wrong sequence of tones are entered, then the controller will energize the PTT relay and send "N_G" in Morse on the audio output terminals. Same goes for taking too long to enter DTMF tones. The controller will time out and key the PTT relay and send "T_O" in Morse on the audio output terminals. If the correct sequence of DTMF tones are sent within the correct time, the controller will key the PTT relay and send either a letter "E" (beep), "K" (as in OK) or "R" (as in Roger). The PTT relay and the Morse status feature can be disabled in the controller setup. The DTMF controller is password protected with a 3 digit passcode. So, to turn a relay on or off, simply send the DTMF passcode(3 digits) + relay number(1-8) + on/off(1 or 0). That's it, a total of 5 digits. Feel free to change the PICAXE code as you require.
DTMF Controller Art Work DTMF Controller Schematic DTMF Controller Board (before etching) DTMF Controller "BASIC" Program
DTMF Controller Board (after etching) DTMF Controller Bill of Material