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Composite Video buffer amplifer circuit using transistors....
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peteb2:
I'm having one of those moments where i just can't recall an arrangement of a couple (or more) transistors that will act as a buffer & increase the level of good old fashioned composite video. The amplitude needs to be overall 1V peak to peak (driving into 75 ohms) consisting of positive going +700mV of the 1Vp-p from 0V (=blanking) for actual video while 0V to -300mV is negative going for the sync. It will end up terminated by 75 ohms so the final output would need to be from a transistor's emitter to sink such a low impedance.... Obviously such a configuration will need split supply rails say +5V, 0V, -5V..... and it'll need an input trim pot to tweak the final output level (i guess) :). This is a PAL colour video signal & yes i could use an opamp but i have hundreds of transistors in the junk spares bin that could do with being put to use...
Appreciate any input. This kind of thing was a common issue a few years years back when analog video ruled the roost and any digital video was but theoretical only!
mikerj:
Something like this maybe?
http://electronschematics.blogspot.com/2011/06/video-amplifier.html
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