At 1" it's just soooo cute!

Forum for discussion of narrow-bandwidth mechanical television

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Re: At 1" it's just soooo cute!

Postby Harry Dalek » Wed Jan 10, 2018 7:08 pm

Since this is Steve's circuit i have a place to put up my tests ,i had came across Steve's monitor before but when you need some thing its a good place to review ...
I pretty much need a circuit like this that i can use to modulate my crt and extract sync pulses ..at the moment i have been testing 400 800 and 1600 hz video with it .
I used smeezekitty's Freenbtv software to make the 64 and 128 line 12.5 hz video for testing here

I have made the circuit up to the ic301 monostable ,the composite video and sync comes out fine out the LM311 ,but using this output for the mono it works but there's a bit of random pulse gitter from the video signal ,i found if i use the 2A output and feed that to pin 4 of the mono the sync pulse out at all 3 line rates are very clean .
i have been naughty and not put in decoupling caps yet but will and see if this makes a difference .
I also did find the circuit is voltage sensitive on the positive side ,which i think might be the 4528 as it only effects that and of cause the variation in my parts and construction....i used a TL084 and series adjusted some resistors to get the correct values .
Still it does what i want so i am happy .
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The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Harry Dalek
"Fester! Don't do that to 'Thing'"
 
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