Version 4
SHEET 1 1380 724
WIRE 400 -240 400 -304
WIRE 16 -224 16 -256
WIRE 400 -128 400 -176
WIRE 16 -112 16 -144
WIRE 240 -112 240 -144
WIRE 400 -32 400 -64
WIRE 160 0 -64 0
WIRE 336 16 224 16
WIRE 80 32 32 32
WIRE 160 32 80 32
WIRE 80 48 80 32
WIRE 80 160 80 128
WIRE 400 240 400 64
WIRE 400 240 112 240
WIRE -64 256 -64 0
WIRE 48 256 -64 256
WIRE 192 272 112 272
WIRE 400 320 400 240
WIRE -64 368 -64 256
WIRE 48 368 -64 368
WIRE 192 368 192 272
WIRE 192 368 128 368
WIRE 192 384 192 368
WIRE 192 480 192 464
WIRE 400 480 400 400
FLAG 16 -112 0
FLAG 16 -256 V+
FLAG 192 -16 V+
FLAG 192 48 0
FLAG 400 -304 V+
FLAG 400 480 0
FLAG 32 32 VSIG
FLAG 80 160 0
FLAG 240 -112 0
FLAG 240 -224 VSIG
FLAG 192 480 0
FLAG 80 288 V+
FLAG 80 224 0
SYMBOL voltage 16 -240 R0
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V1
SYMATTR Value 18V
SYMBOL npn 336 -32 R0
SYMATTR InstName Q1
SYMATTR Value 2N3904
SYMBOL res 384 304 R0
SYMATTR InstName R1
SYMATTR Value 10R
SYMBOL res 96 144 R180
WINDOW 0 36 76 Left 2
WINDOW 3 36 40 Left 2
SYMATTR InstName R2
SYMATTR Value 10k
SYMBOL LED 384 -128 R0
SYMATTR InstName D1
SYMATTR Value STW8B12C
SYMBOL LED 384 -240 R0
SYMATTR InstName D2
SYMATTR Value STW8B12C
SYMBOL voltage 240 -240 R0
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V2
SYMATTR Value ""
SYMBOL Opamps\\opamp2 80 320 R180
SYMATTR InstName U2
SYMATTR Value LM324
SYMBOL res 32 384 R270
WINDOW 0 32 56 VTop 2
WINDOW 3 0 56 VBottom 2
SYMATTR InstName R3
SYMATTR Value 180k
SYMBOL res 176 368 R0
SYMATTR InstName R4
SYMATTR Value 20k
SYMBOL Opamps\\opamp2 192 -48 R0
SYMATTR InstName U1
SYMATTR Value LM324
TEXT 136 112 Left 2 !.include LM324.txt
TEXT -64 -48 Left 2 !.dc V2 0 3.3V 10mV