In my Electronic repair job I found normal multimeter is somewhat limited in certain area. so special tools
are needed for saving a lot of time Ring tester is one of this kind .helping me to check small hi Q inductors SMPS transformer, TV Deflection coils ,LOT ,line driver transformer and almost any inductor working on hi frequency.Normal multimeter can only identify a open coil ,but not a shorted windings.
I found some commercial available ring tester. but it is not available in local shops of my area.also it seems priced high. So I decided to make a ring tester of my own.
Below is the one I successfully made from the junk box components. I found it very useful. and now it is one of my best test tool collection. Two Ic's, few LED's ,one plastic container and few resistors made this wonderful tool. If we test it with primary of SMPS transformer or LOT windings of a good one shows all its LEDs will light. depending on the inductive reactantce the number of LED 's light up. If any short in the windings shows all LEDs off. Any short in secondary side cause all LED OFF except the last one.we can test these transformer without take apart from the board