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Electronic Schematics - D

Dual Tone Multi Frequency Circuits

DTMF Decoder - Uses MT8870 DTMF decoder and PIC microcontroller to decode telephone tones.

DTMF Decoder for PC - Our DTMF decoder can be powered from a 9V battery or from your parallel printer port. It can detect and display all 16 DTMF digits on your computer screen in real-time. The Window's program can be placed.

DTMF Decoder with LCD Display - The DTMF decoder 2 is a useful tool used for decoding DTMF (Dual Tone Multi frequency) generated by telephones.

DTMF Generation with 3.58 MHz Crystal - National Semiconductor Application Note

DTMF Products for you - DTMF decoder can be powered from a 9V battery or from your parallel printer, schematic and windows demo program, design by Schmidt Technologies.

DTMF Proximity Detector

DTMF Radio Remote Control - Here is a circuit of a remote control unit which makes use of the radio frequency signals to control various electrical appliances.  This remote control unit has 4 channels which can be easily extended to 12.

DTMF RECEIVER - Today, most telephone equipment use a DTMF receiver IC. One common DTMF receiver IC is the Motorola MT8870 that is widely used in electronic communications circuits. The MT8870 is an 18-pin IC. It is used in telephones and a variety of other applications. When a proper output is not obtained in projects using this IC, engineers or technicians need to test this IC separately. A quick testing of this IC could save a lot of time in research labs and manufacturing industries of communication instruments.

DTMF Tone Decoder - hears touch tones and displays them as telephone numbers.

Dual Tone Multiple Frequency DTMF - National Semiconductor Application Notes first published04-Nov-1995.

Full-duplex doorphone with 3 Wires connection - a two-way (full-duplex) construction planned for use as doorphone.

Radio Remote Control using DTMF - Here is a circuit of a remote control unit which makes use of the radio frequency signals to control various electrical appliances.  This remote control unit has 4 channels which can be easily extended to 12.  This circuit differs from similar circuits in view of its simplicity and a totally different concept of generating the control signals.

Remote control using telephone - Here is a tele-remote circuit which enables switching "on" and "off" of appliances through Telephone lines. The circuit described here can be used to switch up to nine appliances (corresponding to the digits1 through 9 of DTMF the Telephone key-pad). 

Simulate signals for telecomm tests - 9/11/98 EDN-Design Ideas.....The circuit in Figure 1  is a miniature gadget that is helpful in telecommunication applications. The function of the device is to simulate data flow with predefined patterns and use these patterns to check a cable's or a receiver's functionality.

AN-521: Dual Tone Multiple Frequency DTMF -  National Semiconductor Application Note

AN-666: DTMF Generation with 3.58 MHz Crystal - National Semiconductor Application Note 

Device Control using DTMF - Controlling devices using switches are common. From a few decades controlling devices using remote control switches like infrared remote control switch, wireless remote control switches, light activated switches are becoming popular. But these technologies have their own limitations. Laser beams are harmful to mankind.


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