View Full Version : Colordaptor questions

11-28-2016, 08:32 PM
I'm not sure if this is the correct forum for this question, but here it is: I would like to build a colordaptor. Does anyone know where I can find appropriate color filter plastic for building a color wheel? The delay line apparently needs some space between turns, i.e., it can't be close wound. Would it be possible to use a delay line from an early color set? If so does anyone have one they would be willing to sell. The instructions give a pitch setting for winding one of these on a lathe, but even if I had such a thing I would have no idea how to set it up to do this. If a delay line from an tube color set wouldn't work, is there anyone on the list who understands these instructions for winding one and would be willing to wind one for me, for some price?

11-28-2016, 09:59 PM
An old friend of mine built one of these back in the day, and it was donated to Early Television Museum. They may have info helpful for your project.

11-29-2016, 11:32 PM
I (sort of) built a Colordaptor, and have subsequently scrapped the chassis. It really isn't worth your time. The tri-stable switch circuit is touchy at best, and trying to get the wheel to sync is an exercise in futility. Any time the line voltage would shift, I would loose wheel sync. (AC kicking on, refrigerator cycling, garage door opener, the vacuum cleaner, even the 300 watt bulbs in the basement were enough to screw with the voltage in the house.) Plus, trying to get a vintage set to pass the color burst and getting the Colordaptor to lock onto it is easier said than done. I suggest three possible alternatives to the lowly Colordaptor:

1) Convert a type 630TS (or chassis with similar sweep sections, a 721TS could easily be pressed into service) to run at the NTSC incompatible CBS rates. On the 630TS this involves a handful of passive components being switched out. That's it. Then you can focus on building a wheel control circuit using a saturable reactor. (Trust me, wheel control is a complete and total b*tch to implement... I'm still working out kinks with mine.)

The only pricey part in this is the NTSC to CBS adapter. Mr. Hock's World Converter is about $1000 the last time I looked (and worth every last red cent I might add); we spoke briefly at the museum a year or two ago and he was considering a run of (cheaper?) CBS only boxes. I'm not sure what, if anything, came of that.

Regardless, the CBS solution gives you a MUCH better color picture with less fuss. The dreadful flicker found in the CBS field sequential solution is about as noticeable as 50 Hz TV flicker; in other words, barely. The images are bright, clear, and relatively flicker free. In fact, a good working CBS set produces and image DRAMATICALLY superior to the '54 15 inch NTSC sets.

2) Use Daryl's NTSC to NTSC field sequential box. This box takes a standard NTSC signal and essentially does what the Colordaptor or Col-R-Tel do, less the wheel control circuit. It then spits the field sequential NTSC out at line level to be sent to a modulator. No circuit mods to the TV are required to demodulate the color and send it to the gun of the CRT; you need only make connections under the hood for your wheel control circuit. This is MUCH cheaper (about $200 to $250 IIRC), and the color shouldn't be all smeared and "pastel", but flicker will now be a bit more of an issue.

3) If you absolutely MUST have smeary incoherent tube demodulated NTSC field sequential color, then either a) find a Col-R-Tel (ideally find two and sell me the second :D) or b) build the Jay Stanley circuit instead. It's quite a step up from the Colordaptor, and can be easily adapted to a wheel. In fact, Mr. Stanley gave instructions for this. It's also about twice the work to put together.

I went with the CBS option and haven't looked back. Regardless of what you might choose to do, having an aluminized CRT is absolutely critical. Your color wheel will be absorbing ~90% of the light emitted from the CRT face. This is part of the reason why I'm hoarding 10FP4 and 12KP4 CRTs.

Also, it's in your best interest to use a 10 or 12 inch set. Wheel control grows touchier as wheel mass increases. A heavier wheel is naturally going to resist not only getting up to speed, but the small corrections that need to be made to wheel speed on a continual basis in order for the system to work.

Good speed Phil.

11-30-2016, 08:25 AM
Better than a CT-100? You know what they say about opinions...

There's no convergence so that's a plus, but you can see color rainbows if you look away and back again with a wheel set and a tricolor CRT doesn't do that. Also there are physical limits to the size of wheel, which means even if it could beat a 15G, it loses the next round in favor of a 21AXP22. They are neat though, I'm building one myself. I just don't expect it to outperform my 21-CT55.

11-30-2016, 09:20 AM
I've been to the ETF museum and I've seen the operational CBS monitor numerous times. A few feet away are the Westy and the CT-100. I much prefer the CBS monitor. To each his own.
Moreover, I never said it would outperform a 21 incher, only that it's superior in some regards to the 15 inch sets and the Colordaptor and Col-R-Tel. I also plainly stated that the moment of inertia for a larger wheel is a dealbreaker, even more so than the sheer size.

11-30-2016, 09:45 AM
contact cbenham on this site, who has done all the colorwheel work for ETF and much more, and did an exhaustive search for color filter material.

11-30-2016, 10:45 AM
We all know that the color wheel is the weak point in the field sequential design. However, in this day of LCD displays, how about constructing a screen of complete red, blue and green layers. Place this "screen" in front of the B&W CRT. Then turn on the proper screen when that color raster is received. The main problem is that current (as far as I know) technology has the LCD material switching between opaque and the desired color. In my idea we would need LCD material which switched between transparent and the desired color. Maybe this should be called an LCD "filter". No motors, no wheels and it would switch almost instantaneously. Size would not be a limiting factor. You could build one big enough for your DuMont Sovereign!

Any thoughts?

11-30-2016, 10:54 AM
The guys at JVC beat you to the punch. See this thread:

Dave A
11-30-2016, 10:59 AM
Modern version done already by JVC...and some Textronics I think.

11-30-2016, 12:41 PM
Correct, Tektronix used this for color oscilloscopes.

11-30-2016, 01:12 PM
Correct, Tektronix used this for color oscilloscopes.

I attended a Tektronix new product demonstration and training seminar in Williamsburg in 1993 - the shutter screens were new and the glitch/runt/missing pulse capture was really cool, and are now mainstays in any digital scope. Lots of neat toys, and they fed us lunch!

12-10-2016, 05:07 AM
Here are the color filters you want to use: All made by Roscolux. #25 RED, #76 Blue and #90 Green. This page answers some of your questions: Also here is an article about restoring my Col-R-Tel Converter: Finally here is an article about the color wheel set I built from scratch in 2006: Hope this helps.

12-10-2016, 07:42 PM
I too have seen the sets side by side at the ETF. The CBS (Gray) wins, the
Westy is next, the RCA third.

However ... neither the Westy nor their RCA 15GP22 set compares to my CT-100.
Mine is not quite as good as the Gray ... but most of that
is the fault of CT-100's poor Q first video amp. They put too
much worry into chopping of the response at 0.6 MHz.
Its better to let it fall gradually and smoothly out to 1.1
or 1.2MHz. The CT-100's overall color rendition is excellent
if its set up correctly. Remember ... there are 81 adjustments
to get right. A CBS set has about half that since most of the
work is in the (solid state!) NTSC to sequential converter.