Microchip PIC16F84A & MT8870 DTMF repeater controller

Posted on Feb 5, 2014

This PIC16F84a based repeater (DTMF) controller is very simple & economical to build. It also gives you hand-on experience of using & programming PIC Micro controllers. Controller measures 10cm X 6 CM and may be housed in your repeater project enclosure Controller has 8 OC outputs to drive 8 relays. Outputs are available at 12pin header socket or

Microchip PIC16F84A & MT8870 DTMF repeater controller
Click here to download the full size of the above Circuit.

screw-in terminal blocj where a ribbon cable may be connected. In addition to 8 OC outputs, header/terminal socket also provides 12V, Ground & 5V (for pull-ups only). Controller is without relays & is designed to be accommodated within an existing project, where DTMF control is required. It will drive 5/12V relays of any type, without problems. Firmware for PIC is available here for download in. ASM file with password 1234 which may be changed at the time of programming the PIC. This firmware was tested & controller worked perfectly without missing any command.

Leave Comment

characters left:

New Circuits



Popular Circuits

Ultra Low Power LCD Indicator
Simple 50 to 300 MHz Colpitts Oscillator
loud ringer for phone using ka2411
RGB To Color Difference Converter
reference design modern prtd sensors and delta sigma adcs
relay triac
Circuit From the Past
Servo Motor Control Circuit
Xbee Wireless Servo Motor Control Circuit
DZW75-48 50 50II high-frequency rectifier circuit