Posted on Sep 30, 2012

The crystal oscillator, which uses two sections of IC1, a 4001 quad 2-input NOR gate, is a standard and reliable design. The oscillator`s 1.85-MHz, square-wave output feeds IC2, a 4017 divide-by-10 counter. The count enable and reset terminals, pins 13 and 15, are normally held high by resistor R3, and the counter is activated by bringing those pins low by closing telegraph key S1-an arrangement that guarantees that the final state of IC2 pin 12 is always high.

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

The high on IC2 pin 12 is inverted by a third section of the 4001, IC1c, to prevent de current flow through power amplifier Q1 during key-up periods.

Leave Comment

characters left:

New Circuits



Popular Circuits

60 Watt Audio Power Amplifier
QRD1114IR Sensor
10 watt rf amplifier for 18mhz by
voltage to frequency converter icl8038
HS-3182 ARINC 429 Bus Interface Line Driver Circuit
BASIC CIRCUITRY of Metal Detection