5963

Miniature 9-pin medium-mu twin triode explicitly engineered with a balanced heater and ruggedized cathode for long-life operation in early digital computer multi-vibrator and flip-flop switching circuits. Equivalents: 12AU7 (very similar electrical characteristics), 12AU7A, ECC82. Real-Life Examples: IBM early electronic computing mainframes, vintage industrial industrial counters, custom low-noise audiophile components.