Overview
Retro tech enthusiasts have a soft spot for CRT televisions, and for good reason. The humble CRT’s quirks—geometry, color alignment, and scanline stability—make it both a challenge and a joy to calibrate. A recent entrant in the field of DIY test gear is Nicholas Murray’s pocket-sized Composite Test Pattern Generator. Built around an ESP32 development board, this palm-sized tool outputs a variety of test patterns in both PAL and NTSC, offering a simple, reliable way to verify old displays without lugging heavy test equipment from closet to living room.
What makes it special
Key strengths of Murray’s design include its compact form factor, user-friendly interface, and the ability to switch between standard television formats. The ESP32-based generator is capable of producing classic test images—color bars, grayscale ramps, and geometry grids—needed to assess picture quality on CRTs. This is not a one-trick gadget: it provides a suite of patterns that help you check color fidelity, sharpness, alignment, and the stability of the scan lines. The result is a practical, offline tool you can carry in a pocket or a small toolbox.
PAL vs NTSC: why the distinction matters
Older televisions and monitors were designed around regional broadcast standards. PAL and NTSC have different frame rates, line counts, and color encoding schemes. A reliable test pattern generator that supports both formats lets hobbyists compare how the same device renders images under each standard. It’s particularly useful for owners of multi-regional displays or museums with varied equipment, where consistent calibration across formats is essential.
How it works
The heart of the device is an ESP32 microcontroller, known for its easy USB connectivity, robust GPIO options, and ample processing power for generating video data streams in real time. The generator delivers synchronized video signals compatible with old CRT inputs, and the PAL/NTSC modes ensure compatibility across a broad range of displays. Users typically connect the device to the CRT via standard BNC or RCA inputs, depending on the specific build variant. A minimal user interface—often a handful of buttons or a small onboard display—lets you cycle through patterns and formats without needing a computer in the loop.
Typical use cases
- Calibrating color accuracy: color bars and grayscale ramps help you adjust color hue, saturation, and gamma to match reference values.
- Checking geometry: grid patterns reveal pincushion, keystone, and aspect ratio issues.
- Ensuring stability: moving test patterns can expose flicker, interlacing artifacts, or frame alignment problems.
- Quick field checks: its pocket size makes it convenient for quick measurements at swaps, repair bays, or archival settings.
DIY and availability
As with many ESP32-based projects, builders appreciate the open, approachable nature of the design. If you’re comfortable with electronics tinkering, you can often find community versions, firmware options, or kit components that replicate Murray’s concept. For collectors and restorers who want something ready-to-use, look for variants from enthusiasts and small electronics vendors that emphasize PAL/NTSC compatibility and ease of use.
Getting the most out of your CRTs
When calibrating vintage sets, pair the test pattern generator with a calibrated reference display or a known-good signal path. Ensure your cable quality is solid and that the CRT is warmed up before making adjustments. With the right patterns and a little patience, you’ll enjoy sharper geometry, more accurate colors, and a better viewing experience on a cherished piece of television history.
Conclusion
The pocket-sized Composite Test Pattern Generator is a prime example of how modern miniaturization can breathe new life into retro technology hobbies. By leveraging the ESP32 platform and providing PAL/NTSC compatibility in a portable form, it gives CRT enthusiasts a reliable, accessible tool for precise calibration without bulky gear.
