Version 4 SHEET 1 880 680 WIRE -192 208 -208 208 WIRE -192 256 -208 256 WIRE -144 144 -144 48 WIRE -144 192 -144 144 WIRE -112 48 -144 48 WIRE -112 144 -144 144 WIRE 64 48 32 48 WIRE 64 144 32 144 WIRE 64 144 64 48 WIRE 64 208 64 144 WIRE 96 144 64 144 WIRE 160 192 160 144 WIRE 240 144 160 144 WIRE 240 176 240 144 WIRE 240 272 160 272 WIRE 240 272 240 256 WIRE 352 144 240 144 WIRE 352 176 352 144 WIRE 352 272 240 272 WIRE 352 272 352 240 WIRE 416 144 352 144 WIRE 416 272 352 272 FLAG -144 272 0 FLAG 96 144 l1 FLAG -208 208 Lin1 IOPIN -208 208 In FLAG 64 272 0 FLAG 416 144 4 FLAG -208 256 Lin2 IOPIN -208 256 In FLAG 416 272 3 SYMBOL bi 160 192 R0 WINDOW 3 -26 111 Left 0 SYMATTR Value I=V(4,3)*V(l1)**0.76/113k SYMATTR InstName B1 SYMBOL e -144 176 R0 SYMATTR InstName E1 SYMATTR Value 1 SYMBOL res 224 160 R0 SYMATTR InstName Rdark SYMATTR Value 50MEG SYMBOL res -64 160 R270 WINDOW 0 32 56 VTop 0 WINDOW 3 0 56 VBottom 0 SYMATTR InstName R1 SYMATTR Value 100k SYMBOL cap 48 208 R0 WINDOW 3 -185 124 Left 0 SYMATTR Value Q=51.95u*ln(1+ABS(x)*7.8E-3) SYMATTR InstName C1 SYMBOL cap 336 176 R0 WINDOW 3 32 52 Left 0 SYMATTR Value 3.5p SYMATTR InstName C2 SYMBOL diode -48 128 R90 WINDOW 0 0 32 VBottom 0 WINDOW 3 32 32 VTop 0 SYMATTR InstName D1 SYMATTR Value Dsw SYMBOL res -64 64 R270 WINDOW 0 32 56 VTop 0 WINDOW 3 0 56 VBottom 0 SYMATTR InstName R2 SYMATTR Value 17k SYMBOL diode -112 64 R270 WINDOW 0 32 32 VTop 0 WINDOW 3 0 32 VBottom 0 SYMATTR InstName D2 SYMATTR Value Dsw TEXT -328 104 Left 0 ;Light input/LUX\nV(Lin1,Lin2)\nalways >= 0 ! TEXT 432 208 Left 0 ;LDR out TEXT -320 -312 Left 0 ;Light Dependent Resistor NORP12, made from datasheet by RS Components, 1997\nREM:\n1) static R(Lux) approximated to Fig.4, not to the 2 deviating typical values given\n2) min.Rdark=1 MEG, typical Rdark not specified.\nAssumed here Rdark=50MEG because datasheet curve R(Lux) shown linear\nup to around 1MEG\n3) rise & fall times: rise 3.2m / 14m @1000 / 10 Lux, datasheet: 2.8m / 18m (R=1.1*RL)\n(consider different model for C1 ?)\nfall: 47.6ms / 120ms @1000 / 10 Lux, datasheet 48ms / 120ms (R=10*RL)\nRL : resistance under illumination TEXT -320 -16 Left 0 !.model dsw D(Ron=1 Roff=1G Vfwd=0) TEXT 264 336 Left 0 ;assumed: C(x)=a/(1+b*/x/)