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Old 30th Dec 2017, 5:14 am   #1
Argus25
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Default Auto-detecting 405 line video monitor.

I thought is would be a good Christmas project to make use of a small open frame industrial video monitor and turn it into a handy workshop monitor.

So I installed internal mains psu, made an outer cladding/case for it, arranged external controls and designed a 405 line detector circuit, so as to have it display either 525/625 or 405 line images.

The article that describes how I did it and the theory behind the scan conversion is here:

http://worldphaco.com/uploads/Autode...e_monitor..pdf

I have attached a few images.
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Old 30th Dec 2017, 6:34 pm   #2
Wendymott
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Default Re: Auto-detecting 405 line video monitor.

Nice conversion / modification Hugh ...... Note... when I was in HK.. it was HK Airport - Shenzhen........ Shenzhen - Airport... Home..... No trolling around electronic shops for me.
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Old 2nd Jan 2018, 2:57 pm   #3
astral highway
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Default Re: Auto-detecting 405 line video monitor.

Love it Hugo, really ingenious as well as practical and this converter is def gong on my ‘to build’ list.
Also there is much on pages 5 and 9 relevant to the thread on current and waveforms and you demonstrate eg the sawtooth from a transistor square wave drive and later discuss current analytically on p8. It is superbly documented as always!

Great start to the New YEar !

Thanks Hugo !
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Old 5th Jan 2018, 6:27 am   #4
Argus25
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Default Re: Auto-detecting 405 line video monitor.

Al,

Thanks for those kind remarks.

I have also just updated the article, I found a way to eliminate the H linearity error. It simply required adjustment of the S correction capacitor (yoke coupling capacitor) to allow for the longer scan period.

(some multi-standard CRT monitors switch in different values with mosfets) The scan linearity now on 405 vs 625 line mode is practically identical. It also meant the width control/yoke circuit inductance requires no adjustment between modes which frees up a set of relay contacts to switch in the S correction cap.

Updated article : http://worldphaco.com/uploads/Autode...e_monitor..pdf
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