Version 4
SHEET 1 880 920
WIRE -288 -16 -368 -16
WIRE -224 -16 -288 -16
WIRE 320 -16 -128 -16
WIRE 400 -16 320 -16
WIRE 592 -16 400 -16
WIRE -288 0 -288 -16
WIRE 400 0 400 -16
WIRE 16 112 -96 112
WIRE 400 112 400 80
WIRE 400 112 272 112
WIRE 496 112 400 112
WIRE 400 144 400 112
WIRE -288 240 -288 80
WIRE -176 240 -176 48
WIRE -176 240 -288 240
WIRE 16 240 -32 240
WIRE 320 240 320 -16
WIRE 320 240 272 240
WIRE 320 304 320 240
WIRE 320 304 272 304
WIRE -176 352 -176 240
WIRE -96 400 -96 112
WIRE -96 400 -112 400
WIRE 400 400 400 208
WIRE 400 400 -96 400
WIRE 400 416 400 400
WIRE 496 416 496 112
WIRE -288 448 -288 240
WIRE -288 528 -288 512
WIRE -176 528 -176 448
WIRE -176 528 -288 528
WIRE -32 528 -32 240
WIRE -32 528 -176 528
WIRE 400 528 400 496
WIRE 400 528 -32 528
WIRE 496 528 496 496
WIRE 496 528 400 528
WIRE 592 528 496 528
FLAG 592 -16 OUT
IOPIN 592 -16 Out
FLAG -368 -16 IN
IOPIN -368 -16 Out
FLAG 592 528 GND
IOPIN 592 528 Out
SYMBOL res -304 -16 R0
SYMATTR InstName R1
SYMATTR Value 220
SYMBOL res 480 400 R0
SYMATTR InstName R2
SYMATTR Value {rser}
SYMBOL res 384 -16 R0
SYMATTR InstName R3
SYMATTR Value 10k
SYMBOL cap 384 208 M180
WINDOW 0 24 64 Left 0
WINDOW 3 24 8 Left 0
SYMATTR InstName C1
SYMATTR Value 100pF
SYMBOL Opamps\\LT1431 144 208 R0
SYMATTR InstName U2
SYMBOL res 384 400 R0
SYMATTR InstName R4
SYMATTR Value 10k
SYMBOL pnp -224 48 R270
WINDOW 0 116 31 VRight 0
WINDOW 3 86 6 VRight 0
SYMATTR InstName Q1
SYMATTR Value 2N2905A
SYMBOL pnp -112 352 M0
WINDOW 0 64 32 Left 0
WINDOW 3 64 64 Left 0
SYMATTR InstName Q2
SYMATTR Value 2N2907
SYMBOL cap -304 512 M180
WINDOW 0 24 64 Left 0
WINDOW 3 24 8 Left 0
SYMATTR InstName C2
SYMATTR Value 100nF
TEXT -352 568 Left 0 !.param Vref=12V rser=({Vref}-2.507685V)/250uV
RECTANGLE Normal 592 592 -368 -96