If you are sure C5 install good please check value of C4. If C4 is too big C5 will not be up to do the compensation. You can try disconnect C4 or replace with a smaller value if you have.termin wrote:With mirror I have adjust signal form two display, C8 working , small "too much" have , but C5 has no effekt, have
big "too much" display, what my be wrong?
Anything about this unique oscilloscope DIY kit
I have successfully solved this problem by replacing C7 with 100pF after this was done adjusting C8 trimmer changed the waveform of the test signal. I also replaced C5 trimmer with 22pF cap and got a good square waveform of the test signal. Maybe it helps somebody.
Just in case somebody wants to know the range of FC. My DSO068 measures frequency with accuracy 1Hz up to 8,2MHz. Above that the readings are inaccurate. There is TL082 opamp in the input circuit. It can has a bandwidth up to 3MHz, maybe replacing it with LM6172 (bandwidth up to 100MHz) can increase the range of FC up to 15MHz? The bandwidth cannot exceed the limitation of TLC5510 A/D converter (16MHz) anyway.