Version 4
SHEET 1 880 680
WIRE 80 112 0 112
WIRE 208 112 144 112
WIRE 272 112 208 112
WIRE 384 112 336 112
WIRE 0 144 0 112
WIRE 208 144 208 112
WIRE 384 144 384 112
WIRE 0 256 0 224
WIRE 208 256 208 224
WIRE 208 256 0 256
WIRE 384 256 384 224
WIRE 384 256 208 256
WIRE 208 272 208 256
FLAG 208 272 0
SYMBOL res 192 128 R0
SYMATTR InstName R1
SYMATTR Value 100k
SYMBOL res 368 128 R0
SYMATTR InstName R2
SYMATTR Value 20k
SYMBOL diode 336 96 R90
WINDOW 0 0 32 VBottom 0
WINDOW 3 32 32 VTop 0
SYMATTR InstName D1
SYMATTR Value 1N4148
SYMBOL diode 80 128 R270
WINDOW 0 32 32 VTop 0
WINDOW 3 0 32 VBottom 0
SYMATTR InstName D2
SYMATTR Value 1N4148
SYMBOL voltage 0 128 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V1
SYMATTR Value 3.3V
TEXT -34 296 Left 0 !.tran 0.1