Crt Clock Schematic Jun 2026

The most practical way for a hobbyist to build a dedicated CRT clock is with a schematic based on Frank Techniek's classic design, which is representative of this architecture.

+-------------------------------------------------------------------+ | Microcontroller | | (Generates Time Data, Coordinates X/Y DACs, Controls Z) | +-------------------------------------------------------------------+ | | | v v v +--------------------+ +--------------------+ +-------------+ | Horizontal (X) | | Vertical (Y) | | Blanking (Z)| | DAC & Amp | | DAC & Amp | | Circuit | +--------------------+ +--------------------+ +-------------+ | | | v v v [Deflection Yoke] [Deflection Yoke] [Grid G1] \ / / v v v +-------------------------------------------------------------------+ | CRT Display Tube | | (Requires Filament, G1, G2, and Anode HV) | +-------------------------------------------------------------------+ ^ | +-------------------------------------------------------------------+ | Power Supply Unit (PSU) | | (Outputs: 6.3V, -100V, 400V, 1000V+ Anode) | +-------------------------------------------------------------------+ ⚡ 1. High-Voltage Power Supply (HV PSU)

: The tube itself, which includes the heater, cathode, control grid (G1) for brightness, and focusing anodes. 2. Power Supply Schematic Details

. Unlike standard TVs that use magnetic deflection, these clocks use electrostatic deflection Crt Clock Schematic

The most distinctive and critical part of the schematic is the high-voltage (HV) supply for the CRT's accelerating anode. Many clever circuits exist to generate these voltages.

To help refine your design, tell me more about your specific project goals: What do you plan to use?

: These circuits control the horizontal (X) and vertical (Y) plates of the CRT. Schematics often use dedicated tubes like the EF80 or high-voltage transistors (like the STP2NK90Z ) to amplify low-voltage signals into the hundreds of volts needed to move the electron beam. The most practical way for a hobbyist to

The microcontroller continuously reads the time data, translates it into numerical characters or clock hands, and formats the data for visual output.

A DS3231 or similar highly accurate, temperature-compensated RTC maintains time via an I2C interface, ensuring the clock does not drift.

Parts arrived in small cardboard boxes—vacuum tubes with their glass necks glowing faintly under her lamp, a battered CRT from an old oscilloscope someone had salvaged, a dial machined from brass. The transformer hummed awake with a soft, satisfied buzz. When she first fed power through the circuit and the tubes glowed like tiny moons, she realized she had not just built a clock; she had lit a small sky. Many clever circuits exist to generate these voltages

The MCU holds a vector map of numbers 0 through 9 in its memory. To draw a "0", it sends a rapid sequence of X and Y coordinates to the DACs via the SPI bus. The DACs output a stepping analog voltage between 0V and 5V. 2. Deflection Amplifier Schematic

Amplifies DAC voltages to the high levels needed to move the electron beam.

When drawing the schematic for the deflection system, a differential amplifier design is highly recommended. Applying positive voltage to one plate while applying a matching negative voltage to the opposing plate keeps the electron beam centered perfectly and minimizes geometric distortion. Z-Axis Blanking Control

3. Designing the Schematic: Step-by-Step Circuit Considerations Deflection Circuit Topology

CRTs require a complex mix of voltages. A typical small 3-inch CRT (like the 3BP1 or 3LO1) requires: 6.3V AC or DC. Cathode: -1000V DC.