Re-imagined Baxandall photomultiplier power supply

Tell me about it. I occasionally get called out to remove shredded cardboard carriers "eaten" by expensive precision equipment that uses photomultipliers. The only help I get from the vendor is his advice.

"That's an expensive piece of equipment. Don't scratch anything."

Right. I won't scratch any anodized black metal while I use a forceps to forcibly extract shredded cardboard jammed deep into inaccessible areas crammed full of precision mechanical assemblies. It reminds me of a scene from the movie "Sneakers" where I "get" to play the role of Martin Bishop.

Mother: Either way, you've got a top speed of two inches per second. Any faster than that...

[alarm beeps]

Mother: and, uh, big guys with guns. But you'll probably do fine.

Martin Bishop: Since when am I the one who's...

Mother: This is the same model answering machine that Janek used for the shell of his box, now that's what you'll be carrying across the room at two inches per second. I got that for you because I figured you'd just, you know, want to practice. Remember to go real slow!

Martin Bishop: Slow.

[looks at Crease]

Donald Crease: You get all the *fun* stuff...

--
      __ 
   __/  \ 
  /  \__/ 
  \__/    Don Kuenz 
  /  \__ 
  \__/  \ 
     \__/
Reply to
Don Kuenz
Loading thread data ...

My LTSpice simulation chokes on your MOSFETs.

----------------------------------------------------------------------

Questionable use of curly braces in "l6 n004 +12v 1.545={b5} ipk=0.2 rser=1 rpar=785 cpar=535f mfg="wurth elektronik eisos" pn="742 792 79"" Error: undefined symbol in: "[b5]" Questionable use of curly braces in "l7 n005 n001 1.545={b5} ipk=0.2 rser=1 rpar=785 cpar=535f mfg="wurth elektronik eisos" pn="742 792 79"" Error: undefined symbol in: "[b5]" Circuit: * 20140217 photomultiplier.asc

Error on line 9 : l6 n004 +12v 1.545= (b5) ipk=0.2 rser=1 rpar=785 cpar=535f mfg="wurth elektronik eisos" pn="742 792 79" Unknown parameter "b5" Error on line 29 : l7 n005 n001 1.545= (b5) ipk=0.2 rser=1 rpar=785 cpar=535f mfg="wurth elektronik eisos" pn="742 792 79" Unknown parameter "b5" Direct Newton iteration for .op point succeeded. Singular matrix: Check node q2#base Iteration No. 3 Fatal Error: Singular matrix: check node q2#base Iteration No. 3

--
      __ 
   __/  \ 
  /  \__/ 
  \__/    Don Kuenz 
  /  \__ 
  \__/  \ 
     \__/
Reply to
Don Kuenz

Is your LTSpice up-to-date? Those MOSFETs are straight out of the current L TSpice component library. I needed a 40V drain-to-source breakdown voltage, and that was the library part that looked good.

In fact the error messages you list looks more like it's choking on the Wur th Elektronic ferrite bead, which is another library part from the current library.

And I run my simulations with the "alternate" solver (which seems to blow u p less often) and modified trapezium numerical integration.

--
Bill Sloman, Sydney
Reply to
Bill Sloman

unless you add Bv to the models the breakdown voltage doesn't seem to have any effect

Version 4 SHEET 1 880 680 WIRE 192 64 32 64 WIRE 672 64 192 64 WIRE 32 112 32 64 WIRE 144 240 144 224 WIRE 192 240 144 240 WIRE 624 240 624 224 WIRE 672 240 624 240 WIRE 192 304 192 240 WIRE 672 304 672 240 FLAG 192 304 0 FLAG 32 192 0 FLAG 672 304 0 SYMBOL nmos 144 144 R0 SYMATTR InstName M1 SYMATTR Value AO6408special SYMBOL res 176 48 R0 SYMATTR InstName R1 SYMATTR Value 10 SYMBOL voltage 32 96 R0 WINDOW 3 -299 61 Left 2 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName V1 SYMATTR Value PULSE(0 100 0 1 1 1 1 1) SYMBOL nmos 624 144 R0 SYMATTR InstName M2 SYMATTR Value AO6408 SYMBOL res 656 48 R0 SYMATTR InstName R2 SYMATTR Value 10 TEXT -2 264 Left 2 !.tran 1 TEXT -8 344 Left 2 !.model AO6408special ako:AO6408 Bv=40

-Lasse

Reply to
Lasse Langwadt Christensen

You were right, the problem was actually with the ferrite beads. (The umlaut in the vendor name didn't matter.) The unit of measurement (uH) was munged. I replaced the values of L6 and L7 with 1.545u and it's all better now. :)

I'll give it a try, thank you.

--
      __ 
   __/  \ 
  /  \__/ 
  \__/    Don Kuenz 
  /  \__ 
  \__/  \ 
     \__/
Reply to
Don Kuenz

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.