A520HD - Commodore Amiga RGB to HDTV Component Adapter

Project Status: 
released

A520HDThe GGLABS A520HD is the HDTV equivalent of the classic Commodore A520 TV modulator. Instead of encoding the Amiga video signal to a low quality composite output it converts the RGB output to a high quality YPbPr signal compatible with HDTVs with a component input. The A520HD connects to the Amiga 23-pin video port and is powered directly from the system.

The design is heavily based on our GS2HD released a few months ago.
The circuit is pretty straightforward. U1A, U2A and U3A buffer and amplify the RGB signals (standard non inverting configuration with a gain of 2). U1B, U2B and U3B perform the matrix transformation from RGB to YPbPr according to the standard coefficients for SDTV.

Y = 0.299 * R + 0.587 * G + 0.114 * B
Pb = -0.169 * R - 0.331 * G + 0.500 * B
Pr = 0.500 * R - 0.419 * G - 0.081 * B

L1, L2 and the associated capacitors provide a cleaned up power rails for the sensitive video circuits.

Amiga WorkbenchTest Card
The basic circuit will work with pretty much any operational amplifier. However to achieve good video quality a high speed opamp optimized for video applications is required. Suitable devices are Analog Devices AD8056ANZ and Texas Instruments LM6172IN.

Design Files
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Comments

Hello!

Nice product, I'd like to build it. As you freely distribute the Gerber files, is there a chance that we could have the board files for this so we can panelize the design before sending it off to manufacturing? If not, could you please design a panel (4 boards in one panel, smaller than 10x10 cm) and let us use the Gerbers, please?

Best regards,
Björn

Any PCB manufacturer should be able to use the gerber files to create an array for more efficient SMT assembly.
Please respect the GPL v3 when building the boards.

When will you be producing more A520HD adapters?

We are working on an new design that improves compatibility with certain TV sets.

That's great news. Thanks :-)

The A520HD is great – thanks for sharing the design files! When building one adapter for my own use, I noticed that the silkscreen print of R19 and R25 has been swapped by mistake. Maybe you can correct this for a new revision of the gerber files?

Best regards,
Christian

Good catch. R19 and R25 are indeed swapped in the silkscreen.