Version 4
SHEET 1 1468 680
WIRE 240 64 240 48
WIRE 208 80 160 80
WIRE 304 96 272 96
WIRE 400 96 304 96
WIRE 448 96 400 96
WIRE 544 96 512 96
WIRE 560 96 544 96
WIRE 608 96 560 96
WIRE 720 96 688 96
WIRE 208 112 48 112
WIRE 240 144 240 128
WIRE 400 160 400 96
WIRE 720 160 720 96
WIRE -112 256 -112 208
WIRE 48 256 48 112
WIRE 160 256 160 80
WIRE 400 256 400 224
WIRE 400 256 160 256
WIRE 720 256 720 240
WIRE 720 256 400 256
WIRE 720 272 720 256
WIRE 544 352 544 96
WIRE -112 496 -112 336
WIRE 48 496 48 336
WIRE 48 496 -112 496
WIRE 544 496 544 432
WIRE 544 496 48 496
WIRE 720 496 720 352
WIRE 720 496 544 496
WIRE -112 512 -112 496
FLAG -112 512 0
FLAG 240 48 P5
FLAG -112 208 P5
FLAG 240 144 0
FLAG 48 112 RC
FLAG 560 96 Out
FLAG 304 96 Q
SYMBOL tlc272 240 32 R0
SYMATTR InstName U1
SYMBOL voltage -112 240 R0
SYMATTR InstName V1
SYMATTR Value 5
SYMBOL voltage 48 240 R0
WINDOW 3 14 125 Left 2
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR Value 0
SYMATTR InstName V2
SYMBOL res 704 144 R0
SYMATTR InstName R2
SYMATTR Value 1k
SYMBOL res 704 256 R0
SYMATTR InstName R3
SYMATTR Value 27k
SYMBOL ind 592 112 R270
WINDOW 0 32 56 VTop 2
WINDOW 3 5 56 VBottom 2
SYMATTR InstName L1
SYMATTR Value 100µ
SYMBOL cap 384 160 R0
SYMATTR InstName C2
SYMATTR Value 100n
SYMBOL diode 448 112 R270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName D1
SYMATTR Value BAV99
SYMBOL res 528 336 R0
SYMATTR InstName R4
SYMATTR Value 1k
TEXT 800 208 Left 2 ;Meter
TEXT -96 560 Left 2 !.param tper=1/14.4k
TEXT -96 592 Left 2 !.param ton={tper/256*138}
TEXT 256 560 Left 2 !.tran 1
TEXT 808 312 Left 2 ;Rsense
TEXT 512 560 Left 2 !.step temp -20 80 20