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cga scart adapter

CGA/SCART Adapter Circuit

CGA to SCART adapter has great advantages as it does not require separate power source and that uses very few external components, which can be easily adapted in the SCART connector. The signals from R, G and B pins of the CGA’s board are converted from TTL levels to SCART levels with resistors R4, R5 and R6 and entry’s impedance (75 Ω) of scart inputs.

Output Impedance of voltage dividers thus created is not exactly 75 Ω as specified for SCART inputs, but in practice the behavior seems to result not big differences.

R1-R3 resistors from pin 6 of the CGA’s entrance and pins R, G and B of the SCART connector ensure reduction of 50% of brightness when pin 6 active. From synchronization pulses on horizontal and vertical of CGA board it creates, with the help of R7-R11’s and T1, a composite signal timing (SYNC) and a signal remission for TV.

5V supply for the T1 is obtained from the CGA plate, pin 7.

CGA/Scart Adapter Circuit Schematic

cga to scart adapter

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