The Beckman SP-333 (originally designed by Sperry and later produced by Beckman and Babcock) is a vintage planar neon gas discharge "Panaplex" display. Commonly used in electronics from the 1970s and 1980s, these displays are highly sought after by collectors and hobbyists for retro digital clocks and calculator restorations.
Key Specifications & Features
- Display Configuration: 3-Digit, 7-segment numerical display with decimal points.
- Digit Height: Tiny 7.75 mm (0.333 inches), making it a miniature variant of the larger SP-353.
- Illumination: Emits a distinct, bright neon-orange glow (similar to Nixie tubes).
- Keep-Alive Cathode: Equipped with a keep-alive cathode (unlike its sister model, the SP-733. This feature provides internal ionization to ensure faster, uniform digit ignition and multiplexing without lag.
- Electrical Demands: Requires high-voltage operation. It needs a minimum supply voltage of 160 Vdc (maintaining roughly 135 Vdc after ionization) and typically limits current to around 330 μA per segment.
- Base/Pinout: Utilizes a specialized 28-pin arrangement.