Diagram Exclusive — Blue Ring Tester Schematic

: House the circuit in a shielded plastic project box. Use high-quality, flexible, non-shielded test leads (around 10–15 cm max) terminated with mini-hook clips.

The tester connects in parallel with the inductor under test, forming a resonant circuit with an internal capacitor.

+9V to +12V DC Input │ [ ] R1 (10k) │ ├───●───────┐ │ │ │ [ ] [ ] [ ] R4 (47k) R2 [ ] [ ] R3 [ ] (10k) │ │(10k) │ LM3914 LED Driver │ │ │ ┌─────────────────┐ Pulse Input ●───┼───────┼───►│ Pin 5 (Signal) │ (From MCU/555) │ │ │ │ │ │ [ ] [ ] === │ Pin 1 -> LED 1 │ [ ] R5 [ ] [ ] C2 │ Pin 10 -> LED 10│ [ ] (1k) │ │ (1nF) └────────┬────────┘ │ │ │ │ │ ●────────┴─●────────● │ │ │ │ │ │ │ │ │ │ ===== C1 ├─┐ │ │ │ [ ] R6 (10nF) │ └─┼────────┘ │ [ ] (22k) │ │ │ │ │ │ LM393│ │ │ ●──────────┴─►(Inv) ├───┘ │ │ (Non) │ │ [─] Test ▲ │ │ [─] Probes └────┘ │ │ │ └──────────────────────────────────────────────┴─── GND Components List IC1: LM393 (Low Power Dual Voltage Comparator) IC2: LM3914 (Dot/Bar Display Driver) Resistors: R1, R2, R3: 10kΩ (Metal Film, 1/4W) R4: 47kΩ (1/4W) R5: 1kΩ (1/4W) R6: 22kΩ (1/4W) Capacitors: blue ring tester schematic diagram exclusive

: A switching transistor (often a BC547 or a small MOSFET) pulls the test node down to ground for a few microseconds when triggered by the control circuit, charging the LC tank. 2. The LC Tank Tuning Capacitor

Whether you buy the original AnaTek kit or build your own from a schematic you find online, mastering this tool will undoubtedly save you hours of frustration. Use the exclusive tips and deep technical analysis provided in this guide to build, use, and troubleshoot your own Blue Ring Tester, and you will never again be left wondering if a coil is truly "good" or "bad." : House the circuit in a shielded plastic project box

: High Q-factor resonance. The inductor is functioning beautifully with no shorted loops.

The coil is healthy, has high inductance retention, and no shorted turns. Construction and Calibration Tips +9V to +12V DC Input │ [ ]

Add a BNC connector in parallel with C4 (before the comparator). Connect your oscilloscope to see the actual ringing waveform. A good coil shows >5 visible cycles; a bad coil shows 1-2 cycles.

You can find detailed schematic breakdowns and assembly papers on specialized platforms:

| Reference | Value | Notes | |-----------|-------|-------| | U1 | NE555 | Timer IC | | U2 | LM393 | Dual comparator (one used) | | D1, D2 | 1N4148 | Fast switching diodes | | D3 | Red LED | Fault indicator | | D4 | Green LED | Pass indicator | | C1 | 100nF | Ceramic disc | | C2 | 10nF | Polyester | | C3 | 100µF / 16V | Electrolytic | | C4 | 10pF | Ceramic (critical) | | R1 | 10kΩ | 1/4W | | R2 | 1kΩ | 1/4W | | R3 | 100Ω | 1/4W | | R4 | 1MΩ | 1/4W | | R5 | 47kΩ | 1/4W | | R6 | 10kΩ | 1/4W | | R7 | 330Ω | 1/4W | | R8 | 220Ω | 1/4W | | RV1 | 10kΩ trimpot | Calibration | | Lx | Coil under test | External connection | | Power | 9V battery (or 9-12V DC) | Regulated recommended |