Here’s a functional diagram of the DTMF Shield:
- Operating Voltage: 5v, Current draw: 3mA
- Input signal range: 27.5 to 869mVrms (-29 to 1dBm )
- Trim pot for easy gain adjustment.
- 3.5mm stereo audio jack (TRS) and 0.1″ standard interface headers
- Easy to reconfigure the audio jack pinout
- LED to indicate tone decoded
- 0.79″ x 2.16″, 20mm x 55mm
- DTMF Shield – User Manual
- Library and Sample Sketch: download
- DTMF Module Schematics
- Datasheet for Holtek HT9170B
Demo of DTMF Shield for Arduino:
Other demo videos of the DTMF Shield for Arduino can be found: here
Note: some these videos show an earlier board version with no Arduino headers. Version for sale have headers to right into an Arduino board. It has been tested with the Arduino Uno, and it should also work with the Arduino Leonardo and others.