UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - New Multi-Standards Converter / Convertor Design Discussion

ppppenguin · 9th Jul 2004, 8:41 pm

Fableglade: One small point to remember when running American sets. If they are 525 line sets the line scan frequency is very close to that used for 625 (15734Hz vs 15625Hz) so the line timebase will always lock to a 625 signal. There should be no difficulty getting the field timebase to lock to 50Hz instead of 60Hz. There are other minor differences between the 625/50 and 525/60 waveforms but they don't matter in this context. The only other snag I can think of It is possible that the higher frequency components in a 625 signal will cause buzz on sound with a USA TV.

All you have to worry about is modulating your video on to a suitable VHF carrier and doing sound at the correct spacing. Modern modulators as used in NTSC VCRs should be fine for this.

Darryl: That's an impressive little unit you have designed. I work professionally with Xilinx FPGAs etc and can't see how you can make and sell a box like that for £300, assuming that the price mentioned in one of the other messages is correct. That barely covers all the components and a PCB, let alone assembly and test.

9th Jul 2004, 8:41 pm	#2
ppppenguin Retired Dormant Member Join Date: Dec 2003 Location: North London, UK. Posts: 6,168	Re: New Multi-Standards Converter Fableglade: One small point to remember when running American sets. If they are 525 line sets the line scan frequency is very close to that used for 625 (15734Hz vs 15625Hz) so the line timebase will always lock to a 625 signal. There should be no difficulty getting the field timebase to lock to 50Hz instead of 60Hz. There are other minor differences between the 625/50 and 525/60 waveforms but they don't matter in this context. The only other snag I can think of It is possible that the higher frequency components in a 625 signal will cause buzz on sound with a USA TV. All you have to worry about is modulating your video on to a suitable VHF carrier and doing sound at the correct spacing. Modern modulators as used in NTSC VCRs should be fine for this. Darryl: That's an impressive little unit you have designed. I work professionally with Xilinx FPGAs etc and can't see how you can make and sell a box like that for £300, assuming that the price mentioned in one of the other messages is correct. That barely covers all the components and a PCB, let alone assembly and test.