I have now designed a preheat timer with interlock to make the laser idiot proof, ie to prevent turning it on while the tube is cold, the preheat time is about a minute.
Schematic:
I have now designed a preheat timer with interlock to make the laser idiot proof, ie to prevent turning it on while the tube is cold, the preheat time is about a minute.
Schematic:
One of the zeners in series with 100 or 200 ohms will cover you.
And for the blocking diode i plan to use one or two of these instead of that 1N1190 because i have two i front of me as i type this and i also have the proper heatsinks they screw into:
http://pdf1.alldatasheet.com/datashe.../SKN20/12.html[/QUOTE]
Yep, fine, its the big die in the diode that protects you, not the overvoltage rating, so the semikron part is just fine.
The HV return cap is usually a .1 uf to 1 uf metal can mica sprague or a plastic film 600V WIMA HV film cap. you can see its placement in the lexel 88 head schematic in the FAQ.
sorry, took me a while to get back to you, was in hospital.
Qui habet Christos, habet Vitam!
I should have rented the space under my name for advertising.
When I still could have...
Sounds good, thank you!
Now i just need to hunt down a 10000µF 200V capacitor to keep the voltage smooth.
so i´ve gotten some work done on what is eventually to become a psu, you´ll have to excuse the mess.
Some pics:
Now to the bad news, during a test earlier today i had the voltage at about 140VDC using a 230V 800W heater in parallel with a 230V 2000W heater to simulate a laser tube, i was successfully able to turn the current down from 7A to 3.6A, but only for about 2 seconds before the current shot back up to 7A and the pot no longer did anything, despite having the current spread out over 6 mosfets, atleast one still failed within seconds. The heatsink never made it past luke warm.
Its looking more and more unlikely that i will ever be able to build a working psu and more and more likely that im gonna scrap all this and just buy a fucking psu on ebay.
That's the spirit!
don't give up
I did the same fidling building a variable flyback PSU with the same mosfets... had some popped, had some smoke, but finally achieved the goals
that was a H bridge PWM driven flyback transformer from a sony trinitron computer screen, powered from a bipolar 50VDC 5A source (those transformers are heavy, and they work VERY well for such things as powering a TEA or a small tesla coil)
I´ve started on a new passbank using eight 2N3716´s, if this doesent work, i´ll give up!
Pics:
wow, that's a big one!
did you try to drive your mosfets with a PWM signal? since they are designed for switching applications, they might work well
No, no, no !!!
Do I see it right that all white resistors shorted by green wires ... ?
Do you have a schematic of all the electronics there?
Have you seen this thread on 4HV: http://4hv.org/e107_plugins/forum/fo...php?65917.post ? User kilovolt made a PSU like this.
http://c4r0.byethost9.com/ - If you like lasers, high voltage, x-rays and stuff like that, check out my website
The green "wires" are 330ohm resistors