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Old 22nd Mar 2019, 1:01 am   #155
1100 man
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Join Date: Apr 2016
Location: Ventnor, Isle of Wight, & Great Dunmow, Essex, UK.
Posts: 1,377
Default Re: Hedghog standards converter

I've now fitted the audio modulator chip to the first HH and it works perfectly. The audio quality sounds excellent with no distortion or vision buzz.

The audio carrier pot doesn't seem very critical: midway works fine and it's only towards each end of the pot that the sound gets distorted. With the DVD player I'm using, the audio level pot needs to be up full.

I've fitted the remaining bits to HH No2, and using the FPGA board from No1, that all works fine too. There is still no activity on the LSB on either board, so I guess the fault is on the FPGA board. I'll see what happens when I get the second FPGA board in a couple of weeks.

Notwithstanding the lack of the LSB in the video, the quality is excellent. I've just sat and watched 'Dad's Army' for half an hour and I can't fault it- picture and sound are superb!!

Frank, please don't think I was being critical of the test card- I just like to understand why things are the way they are! After all, I'm not going to sit and watch the TC and it's perfectly useable for setting up raster geometry etc. The greyscale pattern is really useful and something I will use a lot for signal tracing.

The thing that really appealed to me about the HH was the front panel selectable options:- this turns it into a useful piece of test gear.

This has been a hugely enjoyable project and a steep learning curve with the SMD and the computer aspects. Initially I was going to take the easy route and buy a complete unit from 'Freya', but I'm glad I didn't as I've learnt a lot and have two units into the bargain!

Many thanks to everyone that's helped with suggestions and advice, but especially Frank for designing the HH and making that design freely available.

Cheers
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