[sdiy] video buffer

[René Schmitz]

Hi Batz'n'y-all,

An emitter follower with a single transistor will do. At least for a 
composite video signal of TV-quality. I've used that some years ago for 
a video output for my ZX-Spectrum. I think it wasn't more than the 
transistor a 1k resistor from emitter to -5V, and a 75ohms resistor from 
the emitter to the video output. Collector is at 5V. The transistor was 
a BC238C but I guess what ever is in your box will do just fine.

Hope this helps,
  René


Batz Goodfortune wrote:
> Y-ellow All.
>         I don't suppose anyone could point me at a video amp circuit 
> that doesn't use anything exotic by any chance? I wouldn't ask but 
> everything I've found so far uses some part or other that I either, 
> haven't got, can't obtain, or isn't worth spending the bux on. I'm kinda 
> hoping someone might have something stashed away that uses a couple of 
> BC109s or something. :)
> 
> And no coils.
> 
> Actually I don't care what it uses as long as I've got a chance of 
> scrounging it from what I've got.
> 
> It's just to buffer/distribute composite video. The video from my 
> surveillance cameras isn't so important but I need to split the output 
> of my video machine 3 ways with as best quality as I can get without 
> building something that's going to turn into a major project. I'd prefer 
> to use a bunch of op-amps but I don't think 741s would quite cut the 
> cheese in this case. :)
> 
> Case in point. I've got a lot of op-amps but of course they're mainly 
> for audio or voltage buffering type jobs. Not a whole lot particularly 
> suited for composite video. I've got some of those now-obsolete 
> differential current buffer ICs that NSC use to make? I don't need gain 
> but I do need to be able to drive a line.
> 
> I had thought about slaughtering a sacrificial VTR but I'm not really 
> sure what I'm looking at inside those things. Besides, I don't actually 
> have one ready to be sent to the abattoir right now. Still fattening 
> those up for Christmas.
> 
> This is of course one of those projects no-one wants to do so I don't 
> want to actually think about it either. But I'd appreciate a heads-up on 
> any circuits that anyone might have found.
> 
> Thanks in advance.
> 
> Be absolutely Icebox.
> 
>  _ __        _       ____Happiness is a warm penguin____
> | "_ \      | |
> | |_)/  __ _| |_ ____       ALL ELECTRIC KITCHEN
> |  _ \ / _` | __|___ |  Yeti music by Yetis for Yetis
> | |_) | (_| | |_  / /
> |_,__/ \__,_|\__|/ /    Disgusting-> http://all-electric.com
>                 / ,__   Music -----> http://mp3.com/electrickitchen
> Goodfortune    |_____|  Cult  -----> http://www.subgenius.com
> 
> 

-- 
uzs159 at uni-bonn.de
http://www.uni-bonn.de/~uzs159