Crt Clock Schematic ((hot))

The following is a technical narrative describing the design and logic of a discrete logic CRT Clock, a device that turns the ephemeral nature of time into a physical dance of electrons.

2. Simplified Schematic Diagram

                   +15V        +170V        +12V
                    |           |            |
    AC IN -> Bridge -> 7805 -> MCU (Arduino)
                |-> Boost SMPS -> HV (1.2kV)
                |-> 555 timer -> Z-axis driver

MCU PWM1 -> DAC X -> X-amp -> Horizontal Deflection Plate
MCU PWM2 -> DAC Y -> Y-amp -> Vertical Deflection Plate
MCU Digital Out -> Transistor -> CRT Grid (Z)
RTC (DS3231) -- I2C -- MCU

Part 8: Where to Find Pre-Designed Schematics

Instead of designing from scratch, use open-source hardware designs:

  1. Oscilloscope Clock by J. Haartsen (Elektor Electronics): The classic 1990s design using an STM32.
  2. CRT Clock by Mitxela: A modern minimalist design using a 2" CRT and a single IC (MSP430) with clever resistor DACs.
  3. Vectrex MAME Clock: A hack of the Vectorbeam monitor schematics.

Search strings for repositories:

  • site:github.com crt clock schematic kicad
  • "vector clock" crt flyback schematic
  • 3RP1A datasheet and application note

Part 2: The High Voltage Power Supply Schematic (The Flyback)

A CRT is a vacuum capacitor. The anode cap requires +500V to +2kV (for small tubes) to accelerate electrons toward the screen.

Note: Old TV tubes require 15kV. Do not use TV tubes for desk clocks. Crt Clock Schematic

2. "The numbers are squashed on one side."

  • Cause: DC offset on the deflection plates.
  • Fix: Add a 10k potentiometer to zero the differential amplifier output.

Part 6: Putting It All Together – A Complete Bill of Materials (BOM)

Based on a typical electrostatic CRT clock schematic (e.g., "SNTP-CRT" by David Forbes), here is what you need:

| Section | Critical Parts | Value/Rating | | :--- | :--- | :--- | | HV Supply | Ferrite core (EE25), IRF740 MOSFET, UF4007 diodes | 1.2kV out, 30kHz | | Focus/Bias | High voltage resistor chain (10MΩ + 5MΩ trimpot) | 1W, 3kV rating | | Deflection | APEX PA94 or discrete (BF869/BF870) | +/- 100V @ 50mA | | DAC | MCP4922 (12-bit, dual) | SPI interface | | MCU | Teensy 4.0 or STM32F103 | 72MHz+ for vector speed | | Power | 6.3V AC transformer (for heater) + 24V DC supply | Galvanic isolation | The following is a technical narrative describing the

The Cathode Ray Tube Clock: A Synthesis of Vintage Display and Modern Digital Logic

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 CRT Clock. 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.

Differential Drive

A proper schematic uses differential drive. Instead of one plate at 0V and the other at 100V, you drive them symmetrically: -50V and +50V. This doubles the deflection sensitivity and linearity. Part 8: Where to Find Pre-Designed Schematics Instead