Posted on Nov 29, 2012

This circuit shows the TP5700 directly interfacing to a low-voltage DTMF generator. VREGt supplies the necessary 2-V minimum bias to enable the TP5380 to sense key closures and pull its mute output high. VREGt then switches to a 3-V regulated output to sustain the tone dialer during tone generation. The TP5700 DTMF input incorporates the necessary load resistor to V-and provides gain, plus AGC action, to compensate for loop length.

Click here to download the full size of the above Circuit.

A muted tone level is heard in the receiver. For DTMF generators with a higher output level than the TP5380, a resistive potentiometer should be added to reduce the level at the speech circuit DTMF input.

Leave Comment

characters left:

New Circuits



Popular Circuits

from 42 to 88 Mhz Band
A serial cradle
Bandpass filter
60MHz Frequency Meter / Counter 10Hz to 60MHz
bjt transistor circuit finding the resistances
mosfet How to switch between a solar panel and battery
7 band audio graphic equalizer circuit
light flasher pcb
3 Input mic mixer circuit
Experimental Pendulum Clock
simple gauss detection switch
Philco Portable
SEISMIC RADIO 500mHz - 200Hz frequency range
A hi-fi amp around 01