Version 4
SHEET 1 1420 696
WIRE 288 -128 -368 -128
WIRE 1200 -128 544 -128
WIRE -432 -64 -448 -64
WIRE -64 -64 -80 -64
WIRE 128 -64 112 -64
WIRE 720 -64 704 -64
WIRE 912 -64 896 -64
WIRE 1280 -64 1264 -64
WIRE -448 -48 -448 -64
WIRE 112 -48 112 -64
WIRE 720 -48 720 -64
WIRE 1280 -48 1280 -64
WIRE -80 -32 -80 -64
WIRE 912 -32 912 -64
WIRE -448 48 -448 32
WIRE -368 48 -368 -128
WIRE -368 48 -448 48
WIRE -336 48 -368 48
WIRE -80 48 -80 32
WIRE -80 48 -144 48
WIRE 912 48 912 32
WIRE 976 48 912 48
WIRE 1200 48 1200 -128
WIRE 1200 48 1168 48
WIRE 1280 48 1280 32
WIRE 1280 48 1200 48
WIRE 112 96 112 32
WIRE 160 96 112 96
WIRE 720 96 720 32
WIRE 720 96 672 96
WIRE -384 144 -448 144
WIRE -336 144 -384 144
WIRE -80 144 -144 144
WIRE 16 144 -80 144
WIRE 192 144 16 144
WIRE 288 144 544 -128
WIRE 544 144 288 -128
WIRE 816 144 640 144
WIRE 912 144 816 144
WIRE 976 144 912 144
WIRE 1216 144 1168 144
WIRE -80 192 -80 144
WIRE 112 192 112 96
WIRE 288 192 288 144
WIRE 544 192 544 144
WIRE 720 192 720 96
WIRE 912 192 912 144
WIRE -448 240 -448 144
WIRE 16 240 16 144
WIRE 16 240 -16 240
WIRE 48 240 16 240
WIRE 192 240 192 144
WIRE 224 240 192 240
WIRE 640 240 640 144
WIRE 640 240 608 240
WIRE 816 240 816 144
WIRE 816 240 784 240
WIRE 848 240 816 240
WIRE -320 256 -400 256
WIRE -384 304 -400 304
WIRE -320 304 -320 256
WIRE -80 304 -80 288
WIRE 112 304 112 288
WIRE 288 304 288 288
WIRE 544 304 544 288
WIRE 720 304 720 288
WIRE 912 304 912 288
WIRE -448 336 -448 320
WIRE -384 336 -384 304
WIRE -384 336 -448 336
WIRE -448 352 -448 336
WIRE 256 384 240 384
WIRE 240 400 240 384
FLAG -80 304 0
FLAG 112 304 0
FLAG -80 -64 VCC
FLAG 112 -64 VCC
FLAG 160 96 RX
IOPIN 160 96 BiDir
FLAG 240 480 0
FLAG 240 384 VCC
FLAG -320 384 0
FLAG -448 -64 VCC
FLAG -384 144 TX
FLAG -448 352 0
FLAG 288 304 0
FLAG 912 304 0
FLAG 720 304 0
FLAG 912 -64 VCC
FLAG 720 -64 VCC
FLAG 1280 -64 VCC
FLAG 544 304 0
FLAG 1216 144 RX
IOPIN 1216 144 BiDir
FLAG 672 96 TX
IOPIN 672 96 BiDir
SYMBOL npn -16 192 M0
SYMATTR InstName Q1
SYMATTR Value 2SC1815
SYMBOL npn 48 192 R0
SYMATTR InstName Q2
SYMATTR Value 2SC1815
SYMBOL LED -96 -32 R0
SYMATTR InstName D1
SYMATTR Value QTLP690C
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL res 96 -64 R0
SYMATTR InstName R1
SYMATTR Value 1.5k
SYMBOL res -432 48 R180
WINDOW 0 36 76 Left 0
WINDOW 3 36 40 Left 0
SYMATTR InstName R2
SYMATTR Value 1.5k
SYMBOL voltage 240 384 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V1
SYMATTR Value 5V
SYMBOL voltage -320 288 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V2
SYMATTR Value PULSE(5V 0V 25us 1us 1us 49us 100us)
SYMBOL Optos\\PC817C -240 96 R0
SYMATTR InstName U1
SYMBOL sw -448 336 R180
SYMATTR InstName S1
SYMBOL npn 224 192 R0
SYMATTR InstName Q3
SYMATTR Value 2SC1815
SYMBOL npn 848 192 R0
SYMATTR InstName Q4
SYMATTR Value 2SC1815
SYMBOL npn 784 192 M0
SYMATTR InstName Q5
SYMATTR Value 2SC1815
SYMBOL LED 928 -32 M0
SYMATTR InstName D2
SYMATTR Value QTLP690C
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL res 736 -64 M0
SYMATTR InstName R3
SYMATTR Value 1.5k
SYMBOL res 1264 48 M180
WINDOW 0 36 76 Left 0
WINDOW 3 36 40 Left 0
SYMATTR InstName R4
SYMATTR Value 1.5k
SYMBOL Optos\\PC817C 1072 96 M0
SYMATTR InstName U2
SYMBOL npn 608 192 M0
SYMATTR InstName Q6
SYMATTR Value 2SC1815
TEXT 400 376 Left 0 !.tran 0 100us 0
TEXT 400 408 Left 0 !.model SW SW(Ron=1m Vt=2.5V Vh=0V)
TEXT 400 440 Left 0 !.model 2SC1815 NPN(Is=2.04f Xti=3 Eg=1.11 Vaf=6 Bf=400 Ne=1.5 Ise=0\n+ Ikf=20m Xtb=1.5 Br=3.377 Nc=2 Isc=0 Ikr=0 Rc=1 Cjc=1p Mjc=.3333\n+ Vjc=.75 Fc=.5 Cje=25p Mje=.3333 Vje=.75 Tr=450n Tf=20n Itf=0 Vtf=0 Xtf=0)
TEXT -296 424 Left 0 ;10kHz