Spec, did I miss something -or am I second?
Here are some information from the guy which invented this frequency counter / crystal tester:
https://www.qsl.net/dl4yhf/freq_counter/freq_counter.html
Thanks for the the linking to the author! I was wondering how and where to find information on that little XTAL tester yesterday when I traced down a fault that made it stop working*..
Here is mine:
Used two layers of package tape for masking the LED display for better visibility and readability.
And here it is, checking an 8MHz SMD type quartz:
*- I put the quartz all way in sitting on top of the surface of the PCB. The first run was succesful but when I had it assembled into its housing the little gadget didn't work anymore. Traced it down to the 20MHz XTAL didn't start oscillating. I changed the two resonator caps -no success. I exchanged it with the 8MHz quartz -that worked -but obviously that wouldn't count right.
After putting it back in without soldering I noticed that I could get it working in one position but it was failing in another with the same behaviour as before.
Resolution was: The via soldering points are bigger than the isolation diameter of the quartz's legs and would sometimes cause a short to the housing of the quartz.
Temporarily put a piece of paper between PCB an quartz that I removed after soldering and it works happily now.
Nice little piece of kit.