Electric OU: Akula 3V Scoposcopy Example
Using a Function Generator, an Analog Scope and a Frequency Counter, I demonstrate how to find the frequency of any periodic signal even if your scope won’t trigger on it properly.
As long as you can see a pattern in the signal being measured, and can correlate that visually with a sine wave from the FG, you can determine the main frequency using this technique.
The Akula 3V circuit is used as an example Device Under Test to produce the complex signal which looks like a sinusoid but is really noisy and has HF spikes that screw up the DSO’s measurements. You can’t fool the analog scope though: what you get is what you see.
In brief, I am generating a reference signal with the Interstate F43 Function Generator (FG) that is clean, solid and easy to read accurately and precisely by the Philips 6676 Universal Frequency Counter (FC). The noisy signal under test is compared visually to the reference signal on the Tektronix 2213a Analog Oscilloscope (AO). The complete stable waveform is meanwhile being sampled and displayed in the Link DSO.
I believe the basic schematic drawing was first done by Vadik Guk and posted to the forums, then revised a little by Verpies, then I put my own changes in purple on the drawing. Thanks to all for your hard work on this!