Version 4
SHEET 1 2344 2668
WIRE 912 480 624 480
WIRE 624 496 624 480
WIRE 912 544 912 480
WIRE 912 640 912 624
WIRE 624 672 624 576
WIRE 704 672 624 672
WIRE 624 720 624 672
WIRE 528 768 496 768
WIRE 576 768 528 768
WIRE 704 784 672 784
WIRE 784 784 704 784
WIRE 912 784 784 784
WIRE 352 800 208 800
WIRE 528 800 352 800
WIRE 576 800 528 800
WIRE 784 800 784 784
WIRE 912 800 912 784
WIRE 208 816 208 800
WIRE 352 816 352 800
WIRE 496 832 496 768
WIRE 784 896 784 880
WIRE 912 896 912 880
WIRE 208 912 208 896
WIRE 352 912 352 896
WIRE 496 928 496 912
WIRE 592 928 592 848
WIRE 592 928 496 928
WIRE 640 928 592 928
WIRE 656 928 640 928
WIRE 592 944 592 928
WIRE 592 1072 592 1024
WIRE 592 1184 592 1152
FLAG 912 640 0
FLAG 912 896 0
FLAG 208 912 0
FLAG 592 1184 0
FLAG 352 912 0
FLAG 784 896 0
FLAG 528 800 2
FLAG 704 784 3
FLAG 704 672 5
FLAG 528 768 4
FLAG 640 928 1
SYMBOL VOLTAGE 208 800 R0
WINDOW 39 0 0 Left 0
WINDOW 123 0 0 Left 0
SYMATTR InstName V1
SYMATTR Value -20
SYMBOL voltage 912 784 R0
SYMATTR InstName V3
SYMATTR Value 300
SYMBOL voltage 912 528 R0
SYMATTR InstName V4
SYMATTR Value 300
SYMBOL RES 608 480 R0
SYMATTR InstName R1
SYMATTR Value 1
SYMBOL res 336 800 R0
SYMATTR InstName R2
SYMATTR Value 1G
SYMBOL res 768 784 R0
SYMATTR InstName R4
SYMATTR Value 1G
SYMBOL res 576 928 R0
SYMATTR InstName R5
SYMATTR Value 1
SYMBOL res 480 816 R0
SYMATTR InstName R6
SYMATTR Value 1m
SYMBOL voltage 592 1056 R0
SYMATTR InstName V2
SYMATTR Value 5
SYMBOL Valve\\Pentode 624 784 R0
WINDOW 38 50 89 Center 0
SYMATTR InstName U1
SYMATTR SpiceModel 7591Pent
TEXT 192 576 Left 0 !.step V1 -40 0 1 V4 100 500 100
TEXT 192 616 Left 0 !.op
TEXT 176 1184 Left 0 ;Only pin order have to be changed
TEXT 192 464 Left 0 ;Q is always connected to K, either internal or external.