f a very simple robot control circuit using DTMF tones. Dual-tone multi-frequency (DTMF) tones are the sounds you hear when you press keys on a telephone keypad. You can buy a very simple IC (usually used in answsering machines and the like) that takes care of all the filtering and decoding necessary to determine which key was pressed. And because it's just an analog audio signal that is being exchanged, I can use a number of ordinary, low-cost audio transmitter/ reciever pairs for sending that audio signal. The design of the circuit for decoding DTMF tones is pretty straightforward. The CM8870 IC interprets the tones as a 4-bit digital signal. The HCF4514 IC then decodes and stores this onto 16-lanes of output which will switch transistors, which will switch automotive relays, which will operate motors that move the robot.