To prevent lines between numbers, the schematic must include a Z-axis circuit (intensity control) to turn off the electron beam when it moves between digits. Engineering Challenges: Phosphor and Longevity
Start with a known open-source project like the "CRT Clock by J. D. Paul" (available on GitHub). Study the HV section carefully. Build the low-voltage logic first, test the CRT filament, then apply HV last.
. Most modern CRT clock designs, often called "Oscilloscope Clocks," function by treating the CRT like a vector display, using X (horizontal) and Y (vertical) inputs to "draw" the clock face. Core Schematic Sections Power Supply (High Voltage & Filament)
In an age dominated by silent, flat-panel displays and voice-activated smart devices, the warm, glowing flicker of a cathode ray tube (CRT) seems like a relic from a bygone era. Yet, for a niche community of engineers, hobbyists, and retro-computing enthusiasts, the CRT remains a medium of fascination. One of the most compelling projects that bridges the gap between obsolete hardware and functional art is the . Examining the schematic of a CRT clock reveals not just a method of telling time, but a masterclass in analog circuit design, high-voltage safety, and the innovative repurposing of electrostatic deflection. Crt Clock Schematic
PS_HV --> CRT PS_HT --> CRT PS_HT --> X_Amp PS_HT --> Y_Amp
: Some designs use tubes like the EF80 as amplifiers for a vintage aesthetic.
, sometimes up to 1000V+) required to accelerate electrons and produce a sharp beam. To prevent lines between numbers, the schematic must
High-voltage film capacitors can store a dangerous charge long after the clock is unplugged. Always place high-value bleeder resistors (e.g., 4.7MΩ) across the high-voltage filter capacitors to safely drain remaining energy within seconds of power-down.
Your schematic hinges entirely on the type of CRT tube you select. Tubes generally fall into two categories: Magnetic Deflection (Television Tubes)
is commonly used to calculate the time and generate the necessary waveforms. Timekeeping DS3231 Real-Time Clock (RTC) Paul" (available on GitHub)
There’s something mesmerizing about a displaying the time. Unlike a simple LCD or LED clock, a CRT clock is a hybrid of retro hardware and modern microcontroller control. Whether you salvage a small 3-inch green-phosphor tube from an old viewfinder or use a 5-inch oscilloscope tube, the heart of the project lies in the schematic .
Transform digital coordinates into analog voltage steps.