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405-line Pattern Generator
In designTelevisionTest gear405 linesPico
Last updated 14 October 2026
A test generator for 405-line sets, monitors and the 1200B scope TV. It makes composite video with bar patterns, an RF output on any Band I channel carrying that video with System A positive modulation, and a 1 kHz tone on the sound carrier. A frequency counter shows the carrier.
Version A is all analogue: two CMOS 556 timers for the sync and the locked bars, a varactor-tuned oscillator and an MC1496 modulator. Version B uses a Raspberry Pi Pico for the test card, patterns and tone, and an Si5351 for crystal-exact vision and sound carriers together.
At a glance
| Channels | Band I B1–B5 (45.00–66.75 MHz vision), plus an IF position on version B |
|---|---|
| Video | 405 lines, 50 fields; bars locked to line and field; test card on version B |
| Sound | AM, 1 kHz at 30 %, 3.5 MHz below vision |
| Output | Composite 1 V p-p 75 Ω; RF ≈ 30 mV with 0/−20/−40 dB pads |
Block diagram
Click a drawing to open it full size.
Documentation
The full design report, schematics and parts list will be published here once the project has been built, tested and filmed.