CRTs are highly sensitive to stray magnetic fields. Keep your power transformer far away from the tube, or shield the CRT inside a Mu-Metal enclosure to prevent the clock display from shaking.
The power supply is the most critical and dangerous part of the schematic. A typical Oscilloscope Clock Kit uses a transformer or a DC-DC boost converter to generate the following rails:
: High-speed Digital-to-Analog Converters (DACs) translate digital coordinates from a microcontroller (like a PIC or AVR) into analog voltages. These voltages drive the X (horizontal) and Y (vertical) deflection plates to position the electron beam.
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
A high-speed optocoupler (e.g., 6N137) or a high-voltage PNP transistor (e.g., MJE350) shifts a 0V/5V logic signal from the MCU up to the -100V G1 grid reference .
Based on a typical electrostatic CRT clock schematic (e.g., "SNTP-CRT" by David Forbes), here is what you need:
An ESP32 or STM32 is ideal. Vector generation requires high clock speeds (16MHz minimum) to prevent screen flicker. RTC: DS3231 via I2C interface. CRTs are highly sensitive to stray magnetic fields
Building a CRT clock is a perfect blend of modern electronics and "radio days" analog technology. Following a solid schematic will ensure a satisfying and mesmerizing final product. If you are interested, I can: Suggest specific tube types for beginners. Provide a basic ESP32 code framework. Compare different types of HV power supplies. Let me know how you'd like to . How to make Simplest ever Oscilloscope Clock
void generateClockFace(int hour, int minute, int second) float angle_h = (hour % 12) * 30 + minute * 0.5; float angle_m = minute * 6; float angle_s = second * 6;
In an age dominated by OLEDs and TFT touchscreens, the humble Cathode Ray Tube (CRT) has become a relic of a bygone analog era. Yet, for the daring electronic hobbyist, the CRT offers a mesmerizing aesthetic: glowing green or amber phosphor, sharp vectors, and the distinct whine of a flyback transformer. A typical Oscilloscope Clock Kit uses a transformer
Because the CRT grid/cathode is at high voltage (-20V to +10V), you need opto-isolation or a level shifter. A common topology uses a transistor pulling the cathode down relative to the grid.
Translates the 3.3V signals from the ESP32 to the ±100V required by the deflection plates. D. Component Connections X/Y Plates: Connected to the deflection amplifiers.
The schematic must include a circuit to turn the beam on and off (blanking) to draw sharp digits rather than lines connecting them. This is known as Z-axis modulation, typically applied to the control grid (G1) of the CRT. D. The Controller (Brain)
If the electron beam stays on constantly, the CRT will draw messy "trace lines" connecting the individual numbers as it jumps from one digit to the next. The blanking circuit solves this by controlling the Z-axis (beam brightness).
