Simple-touchtonetm-generator

  
The oscillator is a Motorola MC14410CP chip using a 1-MHz crystal. The chip generates both the high and low tones, feeding the energy to the amplifier through 1-K resistors and the 1-I`F capacitor. Values for the output resistors can vary from a few hundred 0 to about 60 KO. The value of the resistor shunting the crystal can vary from about 3 to 15 MO.
Simple-touchtonetm-generator - schematic

The amplifier consists of an LM-380N.




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