into the PSU though???). Should I be switching to an external tickler igniter? The reason I did not use one in the first place is that I suspected that it would not work with a water cooled tube effectively connected to ground.
yeah, the ticklers only work on a few tubes, you were right to do series injection
In factory test, they leave the inputs floating,and it shoots up to the max limit. one of the things I've built but havent got around to trying is using a LEM magnetic current sensor as feedback. I need to determine how much I'd need to lowpass filter the LEM output
so ther NO chance of oscillation, the light board if you have it is a darn handy thing!. Do you need a light board? its one opamp, a 2n2222 and some Rs and Cs. It uses ceramic discs as attenuators in front of a selected silicon photocell. I also have a few of the photcells and pickoffs if you need one.
12 inches is gonna be 1-2 watts or so.
Since I don’t have an optical power meter I had in mind using a thermister on a small block of carbon and a heating wire attached to the thermister. My idea was to use an op amp to control the current to the heating wire to maintain the thermister at a constant temperature well above ambient. The difference between the electrical power going to the heating wire without incident light and that with the laser light incident on the sensor should be a decent measure of the optical power of the laser. It’s not really my idea but just applying the principle of the force restoration balance to
you can do that, or install the light pickoff, which screws to the optics mount, or you can
use a small TE cooler mounted to a heat sink and painted black with carbon paint.
The distance between the two points you mentioned on the tube is a hair over 12 inches. I have included photos with X’s marked on the points I used for measurement in case I used the wrong points.
I imagine that floating inputs might account for erratic behavior like perhaps the mild flickering of optical output I saw. From your look at the schematic does it appear to you that the optical feedback is essential?
The factory techs disconnect it for long periods of time, but yes you want to get some form of current or light control as running at max current all the time is a pain, tube life is very dependant on current, less is better in a watercooled to a point, ie you want four or five amps flowing through it minimum. And in the basement, some times a few mW is all you need to work with. And yes, that would explain some flicker. Dirty optics also are a major contributer to flicker.
When your close to a repair being completed, my medical friend has agreed to walk you through a proper setup for a few minutes on the phone.
I just hope a 1 foot tube is enough voltage drop to make that supply happy, if not we add one or two ohms of series reistance.
This thing really is starting to sound like something in between a lexel 75 and a lexel 88 in size.
Steve
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Originally Posted by mixedgas
buffo
