1218-datasheet.pdf

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Document: Datasheet Date: 11-Mar-12 Model #: 1218 Products Page: www.sunrom.com/p-911.html

DTMF Decoder

This board decodes DTMF signal either from an audio source or phone line to 4 bit binary TTL(5V)level output. It also indicates outputs with LED.Can use directly with microcontrollers to develop various DTMF related applications like remotemonitoring, remote control, Caller ID, Auto Dialer and such.

Features

Decodes DTMF as 4 bit binary

TTL level output for direct connection to

microcontrollers Low power 5V DC operation

LED indication of outputs

Simple to use

Based on excellent MT8870 IC

Applications

Remote Control systems

Caller ID applications

FM receiver based remote control

Remote control using Mobile phone

Specification

Parameter Value Unit Notes

Operating Voltage 5 V DC Regulated power supply input

Operating Current 100 mA

Information

Connect regulated +5V DC supply for operation of board. Outputs Q1-4 and VT are active high

output at 5V level. If any LED is on means that output is at high level. VT LED blinks once a new

DTMF tone is received. The binary data appears at Q1 to Q4. Details of this output is on next page.

Board has two terminals

1) DTMF Audio Input for microphone amp, FM radio receiver, Bluetooth audio receiver and such.

2) Land line phone terminal. Before connection take a Multimeter and identity the plus and minus of

your phone line. Then connect to its terminal of Phone+ and Phone- accordingly.
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Schematic of board

Sample Application

Here is an application used with microcontroller which displays received DTMF tone on sevensegment display.

Program source code download

http://www.sunrom.com/files/1218.zip

TitleCode RevDate: Sheet of

1218 1DTMF Decoder

Sunrom Technologies http://www.sunrom.com

1 1Saturday, March 06, 2010

+ C3

100uF 25V

R2

100K

R1100K

C2100nF

VT

DTMF Audio Input Data Out

CN3SIP2

12

C5

100nF

Phone Line

+

-

U1MT8870

Q111

Q212

Q313

Q4

14

OSC17

OSC28

OE

10

VREF4

IN+

1

IN-2

GS3

IC15

IC26

VSS

9

VDD

18

STD15

ST/GT17 EST16

Y13.5795 MHZ CRYSTAL

R3270K

VCC

VCC

C1100nF

R4470R

R5470R

R6470R

R7470R

R8470R

D2LED

D3LED

D4LED

D5LED

D1LED

C4100nF

VCC

CN2SIP8

1234

5678

VCC

Q3

Q4

Q2Q1

CN1SIP2

12
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Related Links

Datasheet of MT8870http://www.sunrom.com/files/M8870-R3.pdf

About DTMFhttp://en.wikipedia.org/wiki/Dual-tone_multi-frequency_signaling

Google result of MT8870, Many useful referenceshttp://www.google.co.in/search?q=MT8870
http://www.sunrom.com/http://www.sunrom.com/files/M8870-R3.pdfhttp://en.wikipedia.org/wiki/Dual-tone_multi-frequency_signalinghttp://www.google.co.in/search?q=MT8870http://www.google.co.in/search?q=MT8870http://en.wikipedia.org/wiki/Dual-tone_multi-frequency_signalinghttp://www.sunrom.com/files/M8870-R3.pdfhttp://www.sunrom.com/

1218-datasheet.pdf

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