Eric Schlaepfer, known online as TubeTimeUS, built a functional 555-style timer in 2026 using tetrode nuvistors, the miniature vacuum tubes RCA introduced in 1959 to compete directly with bipolar junction transistors. The 8-nuvistor implementation is functionally identical to a semiconductor 555, but demands a dedicated heater supply that burns 7.5 watts before the circuit does anything useful.
Nuvistors are not a curiosity without merit. They are nearly immune to electrostatic discharge, electromagnetic interference, and EMPs that destroy conventional semiconductor electronics. They flew on the 1960s Ranger Moon probes and stayed in commercial television sets, radios, and oscilloscopes into the early 1970s, specifically because of their low-noise, high-frequency performance in VHF and UHF bands.
The original video pairs the build with a technical breakdown of how nuvistors actually work, which is where the real value is. If you want to understand the specific tradeoffs that let a vacuum tube survive into the transistor era, and why that survival eventually ended, this is a precise and hands-on explanation.
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