Schematic & Wiring Diagram

This is a very simple square wave generator circuit built with IC 74LS00 that can accomplish aboveboard signals with frequencies amid 20 Hz and 1 MHz. Its adherence is acceptable abundant for a lot of applications. The achievement freq. is dimensioned through the RC apparatus and time adjournment of the 3 inverter gates. The time adjournment of a argumentation aboideau is the delayed time amid a change of ascribe accompaniment and the consistent change of the achievement state.

To prevent the temperature and voltage supply from affecting the frequency, the oscillator freq. fo must be smaller than 1/2tpn where:

tp = average delay time of each gate
n = the number of gates

The abova described oscillator has a tp of 10ns and n-3. The freq. is therefore:

fo << 1/2tpn = 1/2*10ns*3 = 16.6MHz

The voltage at the gate inputs varies from about _6V to -4V. The oscillation freq. can be made variable by using a 2.2KΩ potentiometer for R.