cyamamot@nunki.usc.edu (Cliff Yamamoto) (04/04/88)
Greetings A/V do-it-yourselfers, This circuit that I'm trying to build seems so simple, I'm surprised I can't find anything on it. I'm interested in building (or locating a cheap source of) video inverters. I've been searching through my IC ref books, but most of the chips I see are for TV's and the like. All I want it to do is take a 75-ohm NTSC video signal w/ negative sync, invert the picture portion on the signal while keeping all the sync, color burst, etc. intact, then output it. Essentially I'd like to use my color negatives and move them to video by camera but invert all the color/luminance values. I went down to my local TV store(s) and I saw a gadget by Sony that (aaacckk!) went for $800. It had this Neg/Pos switch but I don't need all that computerized wiping and color correction junk. If anyone can direct me to a manufacturer (or a mag/book with a simple circuit) that can perform this inexpensively (under $50) I'd appreciate it. Thanx in adv! -------------------- Clifford K. Yamamoto ARPA: cyamamot%nunki.usc.edu@oberon.usc.edu UUCP: cit-vax!oberon.usc.edu!cyamamot@nunki.usc.edu CSNET: cyamamot%nunki.usc.edu@relay.cs.net
snyderw@pawl17.pawl.rpi.edu (Wilson P. Snyder II) (04/05/88)
In article <637@nunki.usc.edu> cyamamot@nunki.usc.edu (Cliff Yamamoto) writes: > This circuit that I'm trying to build seems so simple, I'm surprised I >can't find anything on it. I'm interested in building (or locating a cheap >source of) video inverters. I've been searching through my IC ref books, but >most of the chips I see are for TV's and the like. All I want it to do is >take a 75-ohm NTSC video signal w/ negative sync, invert the picture portion >on the signal while keeping all the sync, color burst, etc. intact, then >output it. Essentially I'd like to use my color negatives and move them to >video by camera but invert all the color/luminance values. >-------------------- >Clifford K. Yamamoto >ARPA: cyamamot%nunki.usc.edu@oberon.usc.edu >UUCP: cit-vax!oberon.usc.edu!cyamamot@nunki.usc.edu >CSNET: cyamamot%nunki.usc.edu@relay.cs.net Several months ago "Radio-Electronics" had the plans for a project that did this and much more, a video-effects generator. It should not be hard to delete sone of the extranious stuff you do not need. Sorry I don't have the date (was 1987 or 1988 issue.) ______________________________________________________________________ Wilson P. Snyder II beowulf!lunge!snyderw@steinmez.UUCP 318 Crockett Hall, RPI (uunet!steinmez!bewulf!lunge!snyderw) Troy, NY 12180-3590 518-276-2764, 802-658-3799 in summer ______________________________________________________________________
markz@ssc.UUCP (Mark Zenier) (04/06/88)
In article <637@nunki.usc.edu>, cyamamot@nunki.usc.edu (Cliff Yamamoto) writes: > > > This circuit that I'm trying to build seems so simple, I'm surprised I > can't find anything on it. I'm interested in building (or locating a cheap > source of) video inverters. ... The uA733 and NE592 are 50-100 mhz video amps that are cheap $1 - $1.50 that have an inverted and non inverted output. They are pin compatible differential amps with the gain set by a resistor. I used one as a video output to convert from a MC6847 to a TTL monitor and found that they drift a bit for a DC amp, but they were spec'd as an AC amp anyway. The output is limited in amplitude but is a couple of volts. Maxim has some new video opamp chips that look hot. The max452 and the max455. Mark Zenier
brown@nicmad.UUCP (Mr. Video) (04/06/88)
In article <637@nunki.usc.edu> cyamamot@nunki.usc.edu (Cliff Yamamoto) writes:
< [...] All I want it to do is
<take a 75-ohm NTSC video signal w/ negative sync, invert the picture portion
<on the signal while keeping all the sync, color burst, etc. intact, then
<output it. Essentially I'd like to use my color negatives and move them to
<video by camera but invert all the color/luminance values.
Someone who knows more about color will have to clarify this, but inverting
the video is fine, but you will have to be careful with the color burst
phasing. Also, something that may get in your way is the orange mask that
is used on all color negs. It WILL get in the way of the color camera.
You may or may not be able to work it out with a color corrector, which
will need to get the negative color balanced correctly. So, the end result
is that you may have to spend the $800, as long as the Sony box has color
correction built in as well.
--
harvard-\ ihnp4--\
Mr. Video !uwvax.................!nicmad!brown
rutgers-/ terminus-/ decvax--/
dya@unccvax.UUCP (Edison Carter) (04/06/88)
In article <1155@ssc.UUCP>, markz@ssc.UUCP (Mark Zenier) writes: > In article <637@nunki.usc.edu>, cyamamot@nunki.usc.edu (Cliff Yamamoto) writes: > > can't find anything on it. I'm interested in building (or locating a cheap > > source of) video inverters. ... > The uA733 and NE592 are 50-100 mhz video amps that are cheap $1 - $1.50 The Elantec EL-2020 operational amplifier is a current mode op amp which has excellent video performance. It can drive two 75 ohm lines to 2 v p-p with no problem. It is about $ 5.50. Its primary advantage over the NE 592 are an order of magnitude better differential gain and phase performance, and a much lower component count (say, 2 resistors, Vcc and Vee, and the chip) for inverting gain. It is also much more stable than the 592, or the Plessey SL541 (yukkk) or the NE 5539 (a nice video amp, but a mean oscillator). You could get the EL 2020 to work nicely in a breadboard. Still another possibility (for crudity, anyway) is using a TL 084 and a 74LS221 to do your gating timing, etc. The last thing you'll need is an FET switch. Make it an Analog Devices ADG 201. The TL 084 doesn't make such a bad sync separator, and at unity gain inversion, won't be gross for home use. You might want a real comparator, though, to drive your gate (you want to preserve the burst and sync, I think). Maxim supposedly has some really neat stuff, too. David Anthony WLQV Detroit
phd@SPEECH1.CS.CMU.EDU (Paul Dietz) (04/07/88)
In article <944@unccvax.UUCP> dya@unccvax.UUCP (Edison Carter) writes: >The last thing you'll >need is an FET switch. Make it an Analog Devices ADG 201. Why? Lot's of companies make versions of this part, and most of them are cheaper. Siliconix and National are the two biggest players in this market, and probably have the cheapest prices. Harris is also a pretty big switch maker. While I have infinite respect for Analog Devices, I think their prices are much too high for these jelly-bean sorts of parts. Especially for the hobbist. Disclaimer: I used to work for National designing analog switches. However, until my parts come to market, I don't care who's you buy. I no longer have any affliation with National Semiconductor, except to occasionally ask what the heck is holding up these parts...