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So using both LM393 comp inputs, the FB ctk is now monitored over a range. Should the POT or other FB passives fail, the LM393 will latch the PS off. Does this provide decent protection?
Got another idea. How about adding a parallel resistor to the POT. If fail open, then PS goes to midpoint. If fail short, PS goes to 1KV shutdown limit and powers off.
Yes, the POT is not good and was known to be problematic since the start. This is probably the most important topic yet, and you beat me to it! The idea was to provide an over-damped comp setup for it to operate on, such that the gain range would not be an issue. It was digging around in...
That diode on the LED drive appears in many examples, so added it. It seems benign, but maybe not. Comp was originally done twice by mistake. So you said to do it on the LT4430 and forward. The LT side comp is still there. With the new addition of the pnp, should more comp be done on the...
Good points, did not notice the redundant comp. The 2nd side 15V is coming from a DCDC isolated module and the 25K pot is an industrial rotary dial with 1M isolation. My idea for backup voltage regulation ckt is to use an lm393 to opto latch the shutdown pin to the uc3846. It does not serve...
Your snubbers are more aggressive then my math(included on dwg). Probably a good thing given assembly quality and bad assumptions. All changes now updated on dwg. Hopefully all your feedback is properly reflected now. Time to build this thing! I'm going to make a 100V version first to prove...
Ah, yes, the idea behind safety was to use a comparator and look for >1KV or 10% FB variation and opto over and shutdown the PWM.
In regards to the now single choke, won't sharing it like that cause some major spikes? Will current keep flowing in one direction upon transition and suddenly be...
After looking at this again, the o/p chokes appear off-balanced. The top loop has to pass through two chokes, the bottom one, just one. So placing a bottom choke between the negative cap and diode, seems scary. So is placing a single one between the cap array coming from the Xformer. Any input?
This has been a 3 year back burner project. HV safety definitely observed and we will be putting this thing in a grounded steel comp case when done. I made a 50khz 1.2KV 4 stage Cockcroft multiplier a few years back and it did ok... 16 diodes somewhat lossy but surprisingly stable with 30%...
Ok, now I see what you are saying! Series bridges charge series caps. The idea behind two independent o/p was stability and easier feedback. A KV of series rectified o/p scares me considering my Tx winding capabilities.
Quick revisit of o/p options! What about a 2 stage full wave...
Ok, so my understanding of the function of the choke may need correction. Are we trying to limit DI/DT into the bulk caps via the Tx? When charging up or during sudden FB duty cycle changes, why wouldn't each section need one? It seems like both sections are being equally used and need the...
Good day! Some clarification needed.
1.) "no lower op choke" Isn't the function of the chokes to lower Tx currents into the caps? Why wouldn't each output need one?
2.) There is already TVS on each bridge o/p. Are you saying each diode should have a tvs and a snub?
3.) Decouple 1uF caps...
Ok, so I'm drudging through feedback docs. There seems to be a concurrent motion that the smaller range, the easier/stable it is. I also found examples of FB from a single output. V regulation for this PS does not have to be perfect. +-10VDC fine. Sag acceptable, so long as it recovers and...
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