DTMF (Dual tone multiple frequency): Circuit diagram of DTMF decoder: Components : 1) Breadboard. 2) IC 7805 and IC MT8870 (DTMF IC): 2) 9V battery: 3) four small LED: Capacitors: 1) 0.1uF 2) 22pF 3) 22oF 4) 10uF connecting wires and cutter: Resistors: 100K, 100K, 330K. Crystal Oscillator (KDS 3.5795) i.e. 3.57MHz Cellphone connector (If […]![]()
