* SPICE netlist
R1 N006 N007 560
R2 N007 0 1.2k
Q1 Rx_Com N007 0 0 BC547C
Q3 Tx_Com N005 Tx_Vito 0 BC547C
D1 Rx_HomeCtrl Rx_Com BAT42
D2 Rx_Vito Rx_Com BAT42
R5 N005 3V3 2.15k
Q2 Tx_Com N001 Tx_HomeCtrl 0 BC547C
R4 N001 3V3 2.15k
R6 N002 Tx_Com 270
D3 3V3 N002 SFH487
R3 3V3 Rx_Com 4.7k
D4 Rx_HomeCtrl Tx_Com BAT42
V1 3V3 0 4.1
V2 Tx_HomeCtrl 0 PULSE(3.3 0 2 0 0 0.1 0.2 3)
V3 Tx_Vito 0 PULSE(3.3 0 0.5 0 0 0.1 0.2 3)
Q4 3V3 N003 N006 0 SFH309
R7 N004 N003 2.15k
V4 N004 N006 PULSE(0 3.3 3.5 0.01 0.01 0.1 0.2 3)
R8 3V3 Rx_HomeCtrl 2.7k
R9 3V3 Rx_Vito 2.7k
.tran 5
+ Cjo=13.3p M=0.333 N=1.70 Tt=7.20n )
+ Cjo=2.97P Vj=.75 M=.333 TT=4.32U type=LED-IR)
+ IKF=10.010E-3 ISE=22.500E-15 NE=1.7206 VAR=300 NK=.2987 RE=59.2
+ CJE=9.212E-12 MJE=0.286 VJE=0.627 FC=0.5 CJC=8.735E-12
+ MJC=0.275 VJC=0.467 TF=0.1E-9)

* LTspice schematic (.asc)
Version 4
SHEET 1 1776 784
WIRE -120 -376 -168 -376
WIRE -8 -376 -40 -376
WIRE -8 -360 -8 -376
WIRE -56 -296 -168 -296
WIRE 184 -296 184 -328
WIRE 184 -296 40 -296
WIRE 248 -296 184 -296
WIRE 616 -296 328 -296
WIRE 616 -232 616 -296
WIRE 72 -200 -168 -200
WIRE 72 -136 72 -200
WIRE 88 -136 72 -136
WIRE 184 -136 184 -296
WIRE 184 -136 152 -136
WIRE 232 -120 232 -168
WIRE 616 -120 616 -168
WIRE 616 -120 232 -120
WIRE 232 -104 232 -120
WIRE 616 -88 616 -120
WIRE 744 -40 680 -40
WIRE 888 -40 824 -40
WIRE 888 -24 888 -40
WIRE -120 -8 -168 -8
WIRE -8 -8 -40 -8
WIRE -8 8 -8 -8
WIRE 72 8 72 -136
WIRE 88 8 72 8
WIRE 232 8 232 -24
WIRE 232 8 152 8
WIRE -56 72 -168 72
WIRE 184 72 184 -136
WIRE 184 72 40 72
WIRE 616 72 616 8
WIRE 616 72 360 72
WIRE 888 72 888 56
WIRE 888 72 616 72
WIRE 232 88 232 8
WIRE 360 152 360 72
WIRE -760 168 -872 168
WIRE -616 168 -616 136
WIRE -616 168 -760 168
WIRE 88 168 -168 168
WIRE 232 168 232 88
WIRE 232 168 152 168
WIRE -616 184 -616 168
WIRE -392 184 -392 136
WIRE 232 200 232 168
WIRE -872 216 -872 168
WIRE -760 216 -760 168
WIRE -504 248 -504 136
WIRE 360 248 360 232
WIRE 360 248 296 248
WIRE 360 264 360 248
WIRE -872 344 -872 296
WIRE -760 344 -760 296
WIRE -616 392 -616 264
WIRE -504 392 -504 328
WIRE -392 392 -392 264
WIRE 232 392 232 296
WIRE 360 392 360 344
FLAG 360 392 0
FLAG 232 392 0
FLAG -168 168 Rx_Vito
FLAG -168 -200 Rx_HomeCtrl
FLAG -168 -296 Tx_HomeCtrl
FLAG -168 72 Tx_Vito
FLAG -168 -8 3V3
FLAG -168 -376 3V3
FLAG -504 392 0
FLAG -392 392 0
FLAG -616 392 0
FLAG -616 136 3V3
FLAG -392 136 Tx_Vito
FLAG -504 136 Tx_HomeCtrl
FLAG 232 -168 3V3
FLAG 184 -328 Tx_Com
FLAG 232 88 Rx_Com
FLAG -872 344 Rx_HomeCtrl
FLAG -760 344 Rx_Vito
SYMBOL res 344 136 R0
SYMATTR InstName R1
SYMATTR Value 560
SYMBOL res 344 248 R0
SYMATTR InstName R2
SYMATTR Value 1.2k
SYMBOL npn 296 200 M0
SYMATTR InstName Q1
SYMATTR Value BC547C
SYMBOL npn 40 8 R90
SYMATTR InstName Q3
SYMATTR Value BC547C
SYMBOL schottky 88 24 R270
SYMATTR InstName D1
SYMATTR Value BAT42
SYMBOL schottky 88 184 R270
SYMATTR InstName D2
SYMATTR Value BAT42
SYMBOL res -24 -24 R90
SYMATTR InstName R5
SYMATTR Value 2.15k
SYMBOL npn 40 -360 R90
SYMATTR InstName Q2
SYMATTR Value BC547C
SYMBOL res -24 -392 R90
SYMATTR InstName R4
SYMATTR Value 2.15k
SYMBOL res 344 -312 R90
SYMATTR InstName R6
SYMATTR Value 270
SYMBOL LED 632 -168 R180
SYMATTR InstName D3
SYMATTR Value SFH487
SYMBOL res 216 -120 R0
SYMATTR InstName R3
SYMATTR Value 4.7k
SYMBOL schottky 88 -120 R270
SYMATTR InstName D4
SYMATTR Value BAT42
SYMBOL voltage -616 168 R0
SYMATTR InstName V1
SYMATTR Value 4.1
SYMBOL voltage -504 232 R0
SYMATTR InstName V2
SYMATTR Value PULSE(3.3 0 2 0 0 0.1 0.2 3)
SYMBOL voltage -392 168 R0
SYMATTR InstName V3
SYMATTR Value PULSE(3.3 0 0.5 0 0 0.1 0.2 3)
SYMBOL npn 680 -88 M0
SYMATTR InstName Q4
SYMATTR Value SFH309
SYMBOL res 840 -56 R90
SYMATTR InstName R7
SYMATTR Value 2.15k
SYMBOL voltage 888 -40 R0
SYMATTR InstName V4
SYMATTR Value PULSE(0 3.3 3.5 0.01 0.01 0.1 0.2 3)
SYMBOL res -888 200 R0
SYMATTR InstName R8
SYMATTR Value 2.7k
SYMBOL res -776 200 R0
SYMATTR InstName R9
SYMATTR Value 2.7k