Blue Ring Tester Schematic Diagram Exclusive [top] -

Blue Ring Tester

The is a specialized diagnostic tool used primarily for identifying shorted turns in high-Q inductive components like flyback transformers (LOPT), switch-mode power supply (SMPS) transformers, and deflection yokes. Schematic and Circuit Overview

"ringing"

The circuit works on the principle of —an LC oscillation created when a pulsed voltage is applied to an inductor. blue ring tester schematic diagram exclusive

• Input: Probe tip -> 4.7 MΩ (HV-rated) series resistor -> node SENSE.
• Protection: Node SENSE to ground through 1 MΩ bleed; TVS to clamp extreme spikes.
• Coupling: Node SENSE -> diode bridge (4 x 1N4007) -> DC node Vp (peak).
• Peak hold: Vp -> 0.1 µF / 1 µF electrolytic (polarity per rectifier) with 10 MΩ bleed.
• Threshold: Vp -> non-inverting input of comparator (e.g., LM393) with inverting input tied to a reference ~2–3 V (generated by resistor divider from low-current Zener or from a resistor-fed divider and capacitor).
• Output drive: Comparator open-collector -> resistor to base of NPN (e.g., 2N3904) -> emitter to ground -> collector to neon lamp (or LED+series resistor) to Vp or small supply.
• Human reference: Touch pad connected to comparator ground via high-value resistor (10 MΩ) to create capacitive reference and bias.

The Blue Ring Tester is a specialized diagnostic tool used primarily for "ringing" a coil. When you apply a pulse to an inductor, it should resonate (or ring) if it is in good condition. If the component has a shorted turn, the magnetic field collapses almost instantly, dampening the resonance. Blue Ring Tester The is a specialized diagnostic

Part 2: How the Blue Ring Tester Works – The Physics of Ringing

The circuit is elegant in its simplicity, usually based on a low-power comparator or a hex inverter (like the 74HCT14) to drive the LED scale. 1. The Pulse Generation Circuit Input: Probe tip -> 4