Spice simulation "off"

V(TP) should be about -5.5V to represent the 55uA current in DVR1. What is the fix?

Version 4 SHEET 1 2748 1048 WIRE 176 64 80 64 WIRE 336 64 176 64 WIRE 464 64 416 64 WIRE 608 64 464 64 WIRE 864 64 608 64 WIRE 608 96 608 64 WIRE -96 128 -192 128 WIRE 80 128 -96 128 WIRE 464 128 464 64 WIRE -96 192 -128 192 WIRE 176 192 176 128 WIRE 176 192 -96 192 WIRE -128 208 -128 192 WIRE -128 208 -192 208 WIRE 80 224 80 128 WIRE 176 224 176 192 WIRE 464 256 464 192 WIRE 864 256 864 224 WIRE 1056 256 864 256 WIRE 176 288 80 288 WIRE 864 304 864 256 WIRE 176 368 176 288 WIRE 1056 368 1056 256 WIRE 1120 368 1056 368 WIRE 1248 368 1200 368 WIRE 1456 368 1248 368 WIRE 1056 400 1056 368 WIRE 1248 400 1248 368 WIRE 1248 480 1248 464 WIRE 1456 480 1248 480 WIRE 592 496 448 496 WIRE 864 496 864 432 WIRE 864 496 592 496 WIRE 1056 496 864 496 WIRE 1248 496 1248 480 WIRE 864 512 864 496 WIRE 656 544 656 528 WIRE 1056 560 1056 496 WIRE 448 576 448 496 WIRE 864 608 864 592 WIRE 656 656 656 624 WIRE 592 672 592 496 WIRE 624 672 592 672 WIRE 864 688 864 672 WIRE 864 688 688 688 WIRE 1056 688 1056 624 WIRE 1056 688 864 688 WIRE 1136 688 1056 688 WIRE 624 704 592 704 WIRE 448 720 448 640 WIRE 656 752 656 720 WIRE 864 800 864 752 WIRE 656 848 656 832 WIRE 592 880 592 704 WIRE 864 880 592 880 WIRE 592 896 592 880 WIRE 864 896 864 880 WIRE 592 1008 592 960 WIRE 864 1008 864 976 FLAG 176 368 0 FLAG -96 128 P1 IOPIN -96 128 In FLAG -96 192 P2 IOPIN -96 192 In FLAG 464 256 0 FLAG 608 416 0 FLAG 864 1008 0 FLAG 1056 464 0 FLAG 1248 496 0 FLAG 592 1008 0 FLAG 448 720 0 FLAG 656 528 0 FLAG 656 848 0 FLAG 1136 688 TP IOPIN 1136 688 Out FLAG 1456 368 J1 IOPIN 1456 368 Out FLAG 1456 480 FORK IOPIN 1456 480 Out SYMBOL diode 96 128 R180 WINDOW 0 -23 0 Left 2 WINDOW 3 45 27 Left 2 SYMATTR InstName D1 SYMATTR Value VR40X SYMBOL diode 192 128 R180 WINDOW 0 -20 1 Left 2 WINDOW 3 -64 -30 Left 2 SYMATTR InstName D2 SYMATTR Value VR40X SYMBOL diode 96 288 R180 WINDOW 0 24 64 Left 2 WINDOW 3 46 29 Left 2 SYMATTR InstName D3 SYMATTR Value VR40X SYMBOL diode 192 288 R180 WINDOW 0 24 64 Left 2 WINDOW 3 -71 65 Left 2 SYMATTR InstName D4 SYMATTR Value VR40X SYMBOL res 432 48 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R1 SYMATTR Value 98.7K SYMBOL cap 448 128 R0 SYMATTR InstName C1 SYMATTR Value 52nF SYMATTR SpiceLine V=1500V SYMBOL res 592 80 R0 SYMATTR InstName R2 SYMATTR Value 5.21Meg SYMBOL res 592 160 R0 SYMATTR InstName R3 SYMATTR Value 5.21Meg SYMBOL res 592 240 R0 SYMATTR InstName R4 SYMATTR Value 5.21Meg SYMBOL res 592 320 R0 SYMATTR InstName R5 SYMATTR Value 5.21Meg SYMBOL res 848 48 R0 SYMATTR InstName R6 SYMATTR Value 5.37Meg SYMBOL res 848 128 R0 SYMATTR InstName R7 SYMATTR Value 5.37Meg SYMBOL zener 880 368 R180 WINDOW 0 -61 38 Left 2 WINDOW 3 -108 7 Left 2 SYMATTR InstName DVR1 SYMATTR Value GV3S800 SYMBOL cap 1040 400 R0 WINDOW 3 23 51 Left 2 SYMATTR Value 10.8nF SYMATTR InstName C2 SYMATTR SpiceLine V=1000V SYMBOL cap 1232 400 R0 SYMATTR InstName C3 SYMATTR Value 51nF SYMATTR SpiceLine V=1600V SYMBOL res 1216 352 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R8 SYMATTR Value 127.6Meg SYMBOL res 880 608 R180 WINDOW 0 36 76 Left 2 WINDOW 3 36 40 Left 2 SYMATTR InstName R9 SYMATTR Value 21.0K SYMBOL res 880 896 R180 WINDOW 0 36 76 Left 2 WINDOW 3 36 40 Left 2 SYMATTR InstName R10 SYMATTR Value 21.04K SYMBOL res 880 992 R180 WINDOW 0 36 76 Left 2 WINDOW 3 36 40 Left 2 SYMATTR InstName R11 SYMATTR Value 73.5K SYMBOL Opamps\\opamp2 656 624 R0 WINDOW 0 21 43 Left 2 WINDOW 3 30 81 Left 2 SYMATTR InstName U1 SYMATTR Value UA741 SYMBOL cap 1040 560 R0 SYMATTR InstName C4 SYMATTR Value 100p SYMBOL cap 576 896 R0 SYMATTR InstName C5 SYMATTR Value 1000p SYMBOL zener 432 576 R0 SYMATTR InstName D5 SYMATTR Value UMZ15K SYMBOL voltage 656 848 R180 WINDOW 0 20 15 Left 2 WINDOW 3 -51 54 Left 2 SYMATTR InstName V3 SYMATTR Value 15V SYMBOL voltage 656 640 R180 WINDOW 0 24 96 Left 2 WINDOW 3 -51 56 Left 2 SYMATTR InstName V2 SYMATTR Value 15V SYMBOL voltage -192 112 R0 WINDOW 0 38 54 Left 2 WINDOW 3 -133 -24 Left 2 WINDOW 123 0 0 Left 2 WINDOW 39 -133 -52 Left 2 SYMATTR InstName V1 SYMATTR Value 1411V SYMATTR SpiceLine Rser=10K Cpar=317nF SYMBOL diode 848 368 R0 WINDOW 0 49 31 Left 2 WINDOW 3 -80 30 Left 2 SYMATTR InstName D6 SYMATTR Value VR40X SYMBOL diode 848 608 R0 SYMATTR InstName D7 SYMATTR Value 1N914 SYMBOL diode 848 688 R0 WINDOW 0 39 28 Left 2 SYMATTR InstName D8 SYMATTR Value 1N914 TEXT 480 216 Left 2 ;1500V TEXT 968 408 Left 2 ;1000V\nCER TEXT 1280 432 Left 2 ;1600V TEXT 1072 648 Left 2 ;MICA TEXT 608 984 Left 2 ;MICA TEXT 464 672 Left 2 ;15V TEXT 1272 352 Left 2 ;+800 VDC OUT TEXT 1280 496 Left 2 ;COMMON OUT TEXT 728 344 Left 2 ;Victoreen\nCorotron TEXT -208 400 Left 2 !.include sp_ua741.mod TEXT -216 432 Left 2 !.MODEL GV3S800 D(IS=800.0E-18 Rs=10K Bv=800 Ibv=20e-18) TEXT -96 -72 Left 2 !.MODEL VR40X D(Rs=1.4 Vj=6.5V Bv=5000 Ibv=100uA) TEXT 104 48 Left 2 ;n001 TEXT 592 32 Left 2 ;n002 TEXT -96 -40 Left 2 ;VB40X 9mmX2mm Mfg not found; use VMI X50SG as ref TEXT -352 232 Left 2 ;HIVOLT POWER SUPPLY\nModel PSL2-5M\n2KV @

5MA\nCONDENSER PRODUCTS CO TEXT 696 288 Left 2 ;note: combo DVR1,D6 fair emulation TEXT 704 8 Left 2 ;//NOTE: measured values shown for parts TEXT -136 608 Left 2 ;//NOTE: measured values shown for parts TEXT 1072 472 Left 2 ;meas at 0V TEXT 440 952 Left 2 ;0.03nF+/-0.02 TEXT 1104 592 Left 2 ;Not meas TEXT 736 440 Left 2 ;I(DVR1,D6) TEXT -352 1032 Left 2 !.op TEXT -320 128 Left 2 !.op TEXT 976 760 Left 2 ;Note: I(Dvr1) -5.53e-005 (typical) so is correct, \n V(tp) of 13.00V incorrect; s/b appx -5.54V
Reply to
Robert Baer
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Current in D5 is 55uA and in R9 is 2nA so looks like the feedback round the op-amp is too blame?

How would you make R9 (21k) * 55uA come to 5.5V?

piglet

Reply to
Piglet

If run transient analysis then Vtp is what would be expected after few hundreds us. So I guess DC operate point simulate is like a time zero run?

What are D7, D8, R10 for?

piglet

Reply to
piglet

  • BINGO! Op amp is obviously railed and doing nothing useful. This is in reality (the physical unit) and in SPICE.
  • I do not. Somehow,the circuit works and one sees -5.5V at TP; that voltage is a very reasonable representation of I(DVR1). I cannot look at a physical working beasty as (at least one) is at Brookhaven National Labs, slightly removed from the West coast.

I am trying to figure out what makes it work and getting nowhere. The board conforms to the circuit. I even measured all parts in-place and documented them. Tried 3 different 741s.

When i first got it, it oscillated at 836Hz, looked looked like a class-C oscillator running. Waveform negative clamped to about -13.5V for about 200uSec, positive excursion about -1V. Strange (?) part is the AVERAGE voltage at TP was -5.5V.

I tried changing R9, D7, D8 and BAM! Failed to either work "properly" (ie: as advertised working) or to oscillate. I see it now in (what i call) the latched state, shown/simulated here.

ANY ideas,no matter how crazy would be welcome.

Thanks.

Reply to
Robert Baer

  • Maybe,i do not know SPICE protocol. Was guessing .op would give steady-state/ final / stable(?) conditions. Hoping SPICE results might be useful for "how to fix".
*Unknown. Circuit from FermiLab in early 1970s. Two known working boards.
Reply to
Robert Baer

I was fiddling around and discovered (on my computer) that if i clicked on the body if DVR1, i get a pull-down menu with a long list of diode models.

I vaguely remember that i found that list as an ASCII file "somewhere" and added a .model for GV3S800, and see it is conflicting with the .model in the simulation file.

I think it would provide sanity if i deleted that file. I cannot find that file, nor the original diode pull-down menu anywhere (original should still exist).

Help?

Reply to
Robert Baer

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