Produce high frequency square wave

Audioguru again

Joined Oct 21, 2019
6,776
The cheap Chinese scope has a small bandwidth that removes the harmonics of a squarewave producing a sinewave and has a fairly low sampling rate which causes the many ripples in the waveform.
 

Thread Starter

MrsssSu

Joined Sep 28, 2021
266
I used a LM119 but it is the same as the LM319.

See Below.
View attachment 255663
Hi, sorry if this was a post a year ago. May I ask how to increase the frequency of square wave produced by adjusting the resistor's values instead of reducing the capacitor C1 in your diagram? This is because I encountered parasitic capacitance which keep changing the fast square wave's frequency and I want to avoid that so I assume I would have to keep the capcaitor value high so we must adjust the resistor values to increase frequency?

Thank you for reading, sir :)
 

Danko

Joined Nov 22, 2017
1,854
May I ask how to increase the frequency of square wave produced by adjusting the resistor's values instead of reducing the capacitor C1
I encountered parasitic capacitance which keep changing the fast square wave's frequency and I want to avoid that so I assume I would have to keep the capcaitor value high so we must adjust the resistor values to increase frequency?
One chip, 10000 pF, 100 Ω, 1 MHz:
1669545603094.png
 

Attachments

ronsimpson

Joined Oct 7, 2019
3,197
When I need a high frequency square wave, I have many crystal oscillators. This one is 100mhz, CMOS 3.3V.
They are stable, and just work. It will take a good scope to see its output.
If you go this direction, there are different types of outputs. TTL, CMOS, ECL(1V).
digikey
1669562841610.png
Old version
1669563203035.png
 
Top