Prefiltered S-video to composite for better pics on vintage color TVs

[wa2ise]

On a vintage color TV, they didn't have comb filters, but only "notch" bandstop and bandpass filters for chroma-luma separation. This assumed that anything above 3 MHz on the demodulated composite video signal belonged to the chroma subcarrier. Problem is that any fine detail in the luma ends up as crawling rainbow colors on the CRT.

But, if I have a source of S-video (separate luma and chroma, like on a better CECB or cable box), I can prefilter the luma (bandstop) and prefilter the chroma (bandpass) so no fine detail luma exists anymore, and thus won't become crawling rainbows on a vintage, or a later production notch filter TV set.


The circuit:
The values of the parts are not that critical. The resulting prefiltered composite video then feeds a TV modulator to send to your vintage color TV set. Your set will present better looking pictures.