MT8870 DTMF Decoder Module 3.5mm Audio Jack

The MT8870 DTMF Decoder Module turns the tones from a phone keypad into digital signals your microcontroller can read, making it a simple way to add phone-based remote control to your projects. Audio is fed in through the onboard 3.5mm audio jack, so you can connect a mobile phone or any audio source using a standard cable. The MT8870 chip recognises all 16 DTMF tone pairs (0-9, A-D, * and #) and outputs the matching 4-bit binary code.

Four data outputs (Q1 to Q4) carry the decoded value, while a delayed steering output (StQ) signals when a valid tone has been detected. Onboard LEDs show the state of the outputs at a glance, which makes testing and debugging quick, even without a serial monitor. The module is powered from a 5V supply and its signals come out on a 9-pin header, so it connects easily to Arduino boards and other 5V microcontrollers.

It is a great fit for phone-controlled robots, home automation, remote switching, and tone-based security projects. Whether you are a hobbyist building your first DTMF project or an experienced maker adding call-based control to a larger system, this compact module gets you decoding tones with minimal wiring and no extra components.

Specification:

• Decoder IC : MT8870
• Audio Input : 3.5mm audio jack
• Detectable Tones : 16 (0-9, A-D, *, #)
• Digital Outputs : 5 (Q1-Q4 4-bit binary, StQ delayed steering)
• Output Indicators : Onboard LEDs
• Header : 9-pin
• Operating Voltage : 5V DC
• Current Consumption : Less than 10mA
• Dimensions : 26mm x 25mm x 12mm
• Package Includes : 1 x MT8870 DTMF Decoder Module