Clock Testing Sans Oscilloscope? | Hackaday

Like several persons who maintenance stuff, [Learn Electronics Repair] has an oscilloscope. But right after working with it to exam a motherboard crystal oscillator, he started imagining about how persons who really don’t individual a scope could possibly do the very same kind of check. He picked up a frequency counter/crystal tester package that was pretty inexpensive — less than $10. He crafted it, and then tried using it to see how effectively it would function in-circuit.

The kit has an abnormal use of 7-section shows to sort-of display screen words and phrases for menus. There is a socket to plug in a crystal for screening, but that won’t do the job for the intended software. He manufactured a smaller extender to simplify connecting crystals even if they are surface mount. He at some point included a BNC socket to the counter enter, but at initial just wired some check qualified prospects right in.

So how was probing with the frequency counter as opposed to working with the scope? You would imagine it really should perform with no authentic issue. On the one hand, it should really be less complicated to study the frequency from the counter, specially if you really don’t have a scope that displays waveform details. On the other hand, the counter doesn’t give you any details about the high quality of the clock source. Is it noisy? Thoroughly clean? 50% responsibility cycle or 10%? Cannot inform without the need of the scope. Turns out, however, that the inexpensive counter wouldn’t browse higher-frequency clock indicators from a motherboard for some cause. It was, however, ready to evaluate enthusiast PWM indicators.

We think the low cost frequency counter doesn’t have a suitable enter phase and was loading down the crystal oscillators. The wire probe likely did not assist any possibly. A good frequency counter would most likely work, but a low-cost meter that had a frequency counter functionality did not do any superior. He also connected a scope probe to both equally devices with no much better results. We wondered if the 10X placing on the probe could possibly have loaded the circuit fewer. We also believe the preamp hack we have covered in advance of could have assisted.

In the end, the low cost minor machine did not look to satisfy his initial objective. But for a uncomplicated crystal tester and frequency counter, it was low-cost sufficient. Whilst a good frequency counter would possibly work, scopes are finding rather lower-price, and they can do a great deal additional.