If you build this from a schematic, calibrate it using a known-good flyback transformer. You want the full "Blue" range to light up on a healthy, high-inductance component.
The "Exclusive" secret to the Blue Ring Tester’s accuracy lies in the . Because inductors can kick back high voltage, the schematic incorporates high-speed clamping diodes (like the 1N4148) to protect the sensitive comparator inputs without dampening the natural ring of the component. Step-by-Step Testing Procedure blue ring tester schematic diagram exclusive
Definitive shorted turn. The component is junk. If you build this from a schematic, calibrate
To get an accurate "Blue" reading, the internal resonance capacitor must be high quality (Polypropylene is best). Because inductors can kick back high voltage, the
The tester connects in parallel with the inductor under test, forming a resonant circuit with an internal capacitor.
Most generic testers use a simple analog decay circuit. The "Blue" version (originally popularized by Bob Parker and Anatek) uses a specific . This ensures that the difference between a good transformer and a "slightly bad" one is visually obvious, rather than a subtle flick of a needle. DIY Tips for Builders