A521HD - Commodore Amiga RGB to HDTV Component Adapter

Submitted by GG on Sun, 01/24/2016 - 17:38
Project Status

A521HDThe GGLABS A521HD is a high performance RGB to YPbPr converter to directly connect an HDTV with component inputs to the A2000/A3000/A4000. The A521HD plugs into the video slot of the big box Amiga.

The design is heavily based on our A520HD 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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