Hacked Gadgets Forum

January 30, 2010

DTMF Decoder Board Project using the MT8870

at 11:28 am. Filed under DIY Hacks, Electronic Hacks


Victor Youk from Razor Concepts has designed a nice DTMF Decoder Board Project. The project is based around the MT8870 DTMF Decoder chip. With this project you will be able to control something from around the block or around the world using a simple telephone. Nice feature of using the MT8870 is you don’t need to program anything, just purchase all the components, stuff them onto a breadboard and have a working circuit in a few hours. Victor has provided a full schematic so you can build your own.

MT8870_DTMF_Decoder_Datasheet (PDF)

“The heart of this device is the MT8870, which is a DTMF to BCD decoder chip. It takes an analog audio input, and converts that to a 4-bit binary output. Those 4 bits are put into a BCD decoder, and that converts that into the corresponding 0-9 output. Various other devices were needed to complete the board, and can be seen in the board layout below.”