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Old 22nd Aug 2022, 5:00 pm   #1
1100 man
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Join Date: Apr 2016
Location: Ventnor, Isle of Wight, & Great Dunmow, Essex, UK.
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Default Using Hedghog Mk1 as a modulator

I built two Hedghog Mk1's a couple of years ago and very good they are too!

They have a 405 line video output socket, but it would be handy to be able to feed 405 line baseband video into the unit and use it as a stand alone modulator. The idea being to use VHS tapes recorded in 405 directly.

Looking at the circuit of the Hedghog, analogue video is fed into pin 9 of the modulator chip, IC5 (MC44BS373).

Could external video be fed in at the same point via a blocking cap and a level control pot, or is it not that simple?

I'm not sure what other inputs the mod chip needs which might not be present without a 625 line input to the unit.

Many thanks
Nick
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