Bob's Basic Digital Ring Tester project

After I designed the "Blue2" microcontroller-based digital ring tester, I
wondered how hard it might be to make a similar tester using ordinary
 components. This was the design I came up with.

Click to watch my video demo on YouTube.

Esau Galvez  built one. Click to see it in action on YouTube.

I don't plan to make and sell them, but I'm making all the design  information
available for anyone who's interested. Everything is in one zip file. Click here
to download it. Have fun!


Update:
A Chinese company is selling them fully built.
See the Ebay listing -> HERE
and the AliExpress listing -> HERE