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.

 

The question is not about where the scope was made (My last Tektronix scope was made in China) but the scope's bandwidth.

 

The Chinese writing on the front of the cheap scope might be saying, "Not for frequencies above 20kHz".

 

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

 

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:

 

I have used SN74S124. Max frequency of 60MHz.

 

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).
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