A520HD - Commodore Amiga RGB to HDTV Component Adapter

Submitted by GG on Fri, 01/15/2016 - 13:33
Project Status

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.

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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,

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,

I'm so stoked about this. Back in the days when I began firing up Amigas again, scandoublers were hard to come by. I finally got a hold on an old one, but it's kind of faulty, so I never got to really using native Amiga video signal on larger, more modern screens.

I would totally buy your scandoubler. All this message just to add to the list of interested people.

Congrats on contributing to keeping the right stuff up and running!

thanks for the feedback.
Please note that this unit is not a scan doubler. Its functionality relies on the scaler/scan doubler that is already in a moder HDTV.


Tue, 05/19/2020 - 14:31

This is great stuff. Any chance to have these back in stock soon? Also, I wonder if the R19<->R25 swap has been fixed in the current silk screen? (being that the comment was 2017 it probably is, but just wanted to confirm)

I am planning to do a new build. The main challenge is to source the DB23 connectors which are becoming very rare. I have a few quotes for new tooling but these are in excess of $5K plus a minimum order of 10,000pcs.


Tue, 08/04/2020 - 05:37

Is the 2.77Kohm (R25 on board) resistor a pull-up, ie can I use a bit bigger value? 2.77Kohm seems to be very rare and almost nowhere available.