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.
