EESchema Schematic File Version 2
LIBS:power
LIBS:device
LIBS:switches
LIBS:relays
LIBS:motors
LIBS:transistors
LIBS:conn
LIBS:linear
LIBS:regul
LIBS:74xx
LIBS:cmos4000
LIBS:adc-dac
LIBS:memory
LIBS:xilinx
LIBS:microcontrollers
LIBS:dsp
LIBS:microchip
LIBS:analog_switches
LIBS:motorola
LIBS:texas
LIBS:intel
LIBS:audio
LIBS:interface
LIBS:digital-audio
LIBS:philips
LIBS:display
LIBS:cypress
LIBS:siliconi
LIBS:opto
LIBS:atmel
LIBS:contrib
LIBS:valves
LIBS:Mechanical
LIBS:mbus_master-cache
EELAYER 25 0
EELAYER END
$Descr A4 11693 8268
encoding utf-8
Sheet 1 1
Title ""
Date ""
Rev ""
Comp ""
Comment1 ""
Comment2 ""
Comment3 ""
Comment4 ""
$EndDescr
$Comp
L Conn_01x02 J2
U 1 1 5A6C5520
P 1700 3300
F 0 "J2" H 1700 3400 50  0000 C CNN
F 1 "Conn_01x02" H 1700 3100 50  0000 C CNN
F 2 "Pin_Headers:Pin_Header_Straight_1x02_Pitch2.54mm" H 1700 3300 50  0001 C CNN
F 3 "" H 1700 3300 50  0001 C CNN
	1    1700 3300
	-1   0    0    1   
$EndComp
$Comp
L GND #PWR01
U 1 1 5A6C5572
P 2400 3400
F 0 "#PWR01" H 2400 3150 50  0001 C CNN
F 1 "GND" H 2400 3250 50  0000 C CNN
F 2 "" H 2400 3400 50  0001 C CNN
F 3 "" H 2400 3400 50  0001 C CNN
	1    2400 3400
	1    0    0    -1  
$EndComp
$Comp
L PWR_FLAG #FLG02
U 1 1 5A6C558D
P 2050 3400
F 0 "#FLG02" H 2050 3475 50  0001 C CNN
F 1 "PWR_FLAG" H 2050 3550 50  0000 C CNN
F 2 "" H 2050 3400 50  0001 C CNN
F 3 "" H 2050 3400 50  0001 C CNN
	1    2050 3400
	-1   0    0    1   
$EndComp
Wire Wire Line
	1900 3200 9200 3200
Wire Wire Line
	1900 3300 2400 3300
Wire Wire Line
	2400 3300 2400 3400
Wire Wire Line
	2050 3400 2050 3300
Connection ~ 2050 3300
$Comp
L PWR_FLAG #FLG03
U 1 1 5A6C5614
P 2050 3050
F 0 "#FLG03" H 2050 3125 50  0001 C CNN
F 1 "PWR_FLAG" H 2050 3200 50  0000 C CNN
F 2 "" H 2050 3050 50  0001 C CNN
F 3 "" H 2050 3050 50  0001 C CNN
	1    2050 3050
	1    0    0    -1  
$EndComp
Wire Wire Line
	2050 3050 2050 3200
Connection ~ 2050 3200
Text Label 2400 3200 1    60   ~ 0
EXT_PWR
Text Notes 850  3350 0    60   ~ 0
External power\n21-42V
$Comp
L Conn_01x02 J1
U 1 1 5A6C56AB
P 1950 5850
F 0 "J1" H 1950 5950 50  0000 C CNN
F 1 "Conn_01x02" H 1950 5650 50  0000 C CNN
F 2 "Pin_Headers:Pin_Header_Straight_1x02_Pitch2.54mm" H 1950 5850 50  0001 C CNN
F 3 "" H 1950 5850 50  0001 C CNN
	1    1950 5850
	-1   0    0    1   
$EndComp
Text Notes 950  5850 0    60   ~ 0
Input signal, TTL\nSendt to m-bus
$Comp
L GND #PWR04
U 1 1 5A6C5767
P 2300 5950
F 0 "#PWR04" H 2300 5700 50  0001 C CNN
F 1 "GND" H 2300 5800 50  0000 C CNN
F 2 "" H 2300 5950 50  0001 C CNN
F 3 "" H 2300 5950 50  0001 C CNN
	1    2300 5950
	1    0    0    -1  
$EndComp
Wire Wire Line
	2150 5850 2300 5850
Wire Wire Line
	2300 5850 2300 5950
$Comp
L BC337 Q3
U 1 1 5A6C58F3
P 5150 5750
F 0 "Q3" H 5350 5825 50  0000 L CNN
F 1 "BC337" H 5350 5750 50  0000 L CNN
F 2 "TO_SOT_Packages_THT:TO-92_Molded_Narrow" H 5350 5675 50  0001 L CIN
F 3 "" H 5150 5750 50  0001 L CNN
	1    5150 5750
	1    0    0    -1  
$EndComp
$Comp
L R R1
U 1 1 5A6C5956
P 4150 5750
F 0 "R1" V 4230 5750 50  0000 C CNN
F 1 "10k" V 4150 5750 50  0000 C CNN
F 2 "Resistors_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal" V 4080 5750 50  0001 C CNN
F 3 "" H 4150 5750 50  0001 C CNN
	1    4150 5750
	0    1    1    0   
$EndComp
Wire Wire Line
	2150 5750 4000 5750
Wire Wire Line
	4300 5750 4950 5750
$Comp
L GND #PWR05
U 1 1 5A6C59DD
P 5250 6150
F 0 "#PWR05" H 5250 5900 50  0001 C CNN
F 1 "GND" H 5250 6000 50  0000 C CNN
F 2 "" H 5250 6150 50  0001 C CNN
F 3 "" H 5250 6150 50  0001 C CNN
	1    5250 6150
	1    0    0    -1  
$EndComp
Wire Wire Line
	5250 5950 5250 6150
$Comp
L D_Zener_Small_ALT D1
U 1 1 5A6C5A7F
P 5250 3550
F 0 "D1" V 5250 3650 50  0000 C CNN
F 1 "13V" H 5250 3460 50  0000 C CNN
F 2 "Diodes_THT:D_5W_P12.70mm_Horizontal" V 5250 3550 50  0001 C CNN
F 3 "" V 5250 3550 50  0001 C CNN
	1    5250 3550
	0    1    1    0   
$EndComp
Wire Wire Line
	5250 3200 5250 3450
Wire Wire Line
	4400 4350 5750 4350
$Comp
L Conn_01x02 J3
U 1 1 5A6C5F4D
P 7300 3450
F 0 "J3" H 7300 3550 50  0000 C CNN
F 1 "Conn_01x02" H 7300 3250 50  0000 C CNN
F 2 "Pin_Headers:Pin_Header_Straight_1x02_Pitch2.54mm" H 7300 3450 50  0001 C CNN
F 3 "" H 7300 3450 50  0001 C CNN
	1    7300 3450
	1    0    0    1   
$EndComp
Wire Wire Line
	7100 3350 6750 3350
Wire Wire Line
	6750 3350 6750 3200
Connection ~ 5250 3200
Text Label 6400 3200 0    60   ~ 0
MBus+
Text Label 6400 3750 0    60   ~ 0
MBus-
$Comp
L BD136 Q4
U 1 1 5A6C614C
P 5950 4350
F 0 "Q4" H 6150 4425 50  0000 L CNN
F 1 "BD136" H 6150 4350 50  0000 L CNN
F 2 "TO_SOT_Packages_THT:TO-126_Vertical" H 6150 4275 50  0001 L CIN
F 3 "" H 5950 4350 50  0001 L CNN
	1    5950 4350
	1    0    0    1   
$EndComp
Wire Wire Line
	6050 3200 6050 3350
Connection ~ 6050 3200
$Comp
L GND #PWR06
U 1 1 5A6C640E
P 6050 5900
F 0 "#PWR06" H 6050 5650 50  0001 C CNN
F 1 "GND" H 6050 5750 50  0000 C CNN
F 2 "" H 6050 5900 50  0001 C CNN
F 3 "" H 6050 5900 50  0001 C CNN
	1    6050 5900
	1    0    0    -1  
$EndComp
Wire Wire Line
	6050 3750 6750 3750
Wire Wire Line
	6750 3750 6750 3450
Wire Wire Line
	6750 3450 7100 3450
Connection ~ 6050 3750
Text Notes 7550 3450 0    60   ~ 0
M-bus output signal
Wire Wire Line
	6050 3650 6050 4150
Text Notes 3000 1650 0    60   ~ 0
Schematic inspired by https://github.com/rscada/libmbus/blob/master/hardware/MBus_USB.pdf\nmentioned in https://electronics.stackexchange.com/a/214477/568.\n\nMade more robust by using a zener diodes so that the voltage drop is exact and that supply voltage does not matter.
Wire Notes Line
	2900 1250 8750 1250
Wire Notes Line
	8750 1250 8750 1800
Wire Notes Line
	8750 1800 2900 1800
Wire Notes Line
	2900 1800 2900 1250
$Comp
L R R6
U 1 1 5A70E602
P 6050 3500
F 0 "R6" H 6150 3500 50  0000 C CNN
F 1 "220k" V 6050 3500 50  0000 C CNN
F 2 "Resistors_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal" V 5980 3500 50  0001 C CNN
F 3 "" H 6050 3500 50  0001 C CNN
	1    6050 3500
	1    0    0    -1  
$EndComp
$Comp
L R R2
U 1 1 5A92EF05
P 5250 4900
F 0 "R2" V 5330 4900 50  0000 C CNN
F 1 "8.2k" V 5250 4900 50  0000 C CNN
F 2 "Resistors_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal" V 5180 4900 50  0001 C CNN
F 3 "" H 5250 4900 50  0001 C CNN
	1    5250 4900
	1    0    0    -1  
$EndComp
Wire Wire Line
	5250 5050 5250 5550
Wire Wire Line
	5250 3650 5250 4750
Connection ~ 5250 4350
$Comp
L BC337 Q1
U 1 1 5A92F34B
P 3500 4650
F 0 "Q1" H 3700 4725 50  0000 L CNN
F 1 "BC337" H 3700 4650 50  0000 L CNN
F 2 "TO_SOT_Packages_THT:TO-92_Molded_Narrow" H 3700 4575 50  0001 L CIN
F 3 "" H 3500 4650 50  0001 L CNN
	1    3500 4650
	1    0    0    -1  
$EndComp
$Comp
L GND #PWR07
U 1 1 5A92F352
P 3600 5050
F 0 "#PWR07" H 3600 4800 50  0001 C CNN
F 1 "GND" H 3600 4900 50  0000 C CNN
F 2 "" H 3600 5050 50  0001 C CNN
F 3 "" H 3600 5050 50  0001 C CNN
	1    3600 5050
	1    0    0    -1  
$EndComp
Wire Wire Line
	3600 4850 3600 5050
$Comp
L R R4
U 1 1 5A92F359
P 3600 3500
F 0 "R4" V 3680 3500 50  0000 C CNN
F 1 "10k" V 3600 3500 50  0000 C CNN
F 2 "Resistors_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal" V 3530 3500 50  0001 C CNN
F 3 "" H 3600 3500 50  0001 C CNN
	1    3600 3500
	1    0    0    -1  
$EndComp
Wire Wire Line
	3600 3650 3600 4450
$Comp
L R R3
U 1 1 5A92F5C3
P 3100 4650
F 0 "R3" V 3180 4650 50  0000 C CNN
F 1 "10k" V 3100 4650 50  0000 C CNN
F 2 "Resistors_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal" V 3030 4650 50  0001 C CNN
F 3 "" H 3100 4650 50  0001 C CNN
	1    3100 4650
	0    1    1    0   
$EndComp
Wire Wire Line
	2700 5750 2700 4650
Wire Wire Line
	2700 4650 2950 4650
Connection ~ 2700 5750
Wire Wire Line
	3250 4650 3300 4650
Wire Wire Line
	3600 3350 3600 3200
Connection ~ 3600 3200
$Comp
L BC337 Q2
U 1 1 5A92F825
P 4300 4000
F 0 "Q2" H 4500 4075 50  0000 L CNN
F 1 "BC337" H 4500 4000 50  0000 L CNN
F 2 "TO_SOT_Packages_THT:TO-92_Molded_Narrow" H 4500 3925 50  0001 L CIN
F 3 "" H 4300 4000 50  0001 L CNN
	1    4300 4000
	1    0    0    -1  
$EndComp
$Comp
L R R5
U 1 1 5A92F832
P 4400 3500
F 0 "R5" V 4480 3500 50  0000 C CNN
F 1 "10k" V 4400 3500 50  0000 C CNN
F 2 "Resistors_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal" V 4330 3500 50  0001 C CNN
F 3 "" H 4400 3500 50  0001 C CNN
	1    4400 3500
	1    0    0    -1  
$EndComp
Wire Wire Line
	4400 3650 4400 3800
Wire Wire Line
	4400 3350 4400 3200
Connection ~ 4400 3200
Wire Wire Line
	4100 4000 3600 4000
Connection ~ 3600 4000
Wire Wire Line
	4400 4200 4400 4350
$Comp
L R R7
U 1 1 5A931949
P 6050 5450
F 0 "R7" H 6150 5450 50  0000 C CNN
F 1 "82" V 6050 5450 50  0000 C CNN
F 2 "Resistors_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal" V 5980 5450 50  0001 C CNN
F 3 "" H 6050 5450 50  0001 C CNN
	1    6050 5450
	1    0    0    -1  
$EndComp
Wire Wire Line
	6050 5900 6050 5600
Wire Wire Line
	6050 4550 6050 5300
$Comp
L BC337 Q5
U 1 1 5A931D4A
P 8350 5050
F 0 "Q5" H 8550 5125 50  0000 L CNN
F 1 "BC337" H 8550 5050 50  0000 L CNN
F 2 "TO_SOT_Packages_THT:TO-92_Molded_Narrow" H 8550 4975 50  0001 L CIN
F 3 "" H 8350 5050 50  0001 L CNN
	1    8350 5050
	1    0    0    -1  
$EndComp
Wire Wire Line
	8150 5050 6050 5050
Connection ~ 6050 5050
$Comp
L GND #PWR08
U 1 1 5A931EC5
P 8450 5500
F 0 "#PWR08" H 8450 5250 50  0001 C CNN
F 1 "GND" H 8450 5350 50  0000 C CNN
F 2 "" H 8450 5500 50  0001 C CNN
F 3 "" H 8450 5500 50  0001 C CNN
	1    8450 5500
	1    0    0    -1  
$EndComp
Wire Wire Line
	8450 5500 8450 5250
$Comp
L Conn_01x02 J4
U 1 1 5A932150
P 10100 5000
F 0 "J4" H 10100 5100 50  0000 C CNN
F 1 "Conn_01x02" H 10100 4800 50  0000 C CNN
F 2 "Pin_Headers:Pin_Header_Straight_1x02_Pitch2.54mm" H 10100 5000 50  0001 C CNN
F 3 "" H 10100 5000 50  0001 C CNN
	1    10100 5000
	1    0    0    1   
$EndComp
Text Notes 10300 5000 0    60   ~ 0
RxD output signal
$Comp
L GND #PWR09
U 1 1 5A932321
P 9900 5500
F 0 "#PWR09" H 9900 5250 50  0001 C CNN
F 1 "GND" H 9900 5350 50  0000 C CNN
F 2 "" H 9900 5500 50  0001 C CNN
F 3 "" H 9900 5500 50  0001 C CNN
	1    9900 5500
	1    0    0    -1  
$EndComp
Wire Wire Line
	9900 5500 9900 5000
$Comp
L D_Zener_Small_ALT D2
U 1 1 5A9323FA
P 9200 4900
F 0 "D2" V 9200 5000 50  0000 C CNN
F 1 "4.7V" H 9200 4810 50  0000 C CNN
F 2 "Diodes_THT:D_A-405_P7.62mm_Horizontal" V 9200 4900 50  0001 C CNN
F 3 "" V 9200 4900 50  0001 C CNN
	1    9200 4900
	0    1    1    0   
$EndComp
$Comp
L GND #PWR010
U 1 1 5A9324F7
P 9200 5500
F 0 "#PWR010" H 9200 5250 50  0001 C CNN
F 1 "GND" H 9200 5350 50  0000 C CNN
F 2 "" H 9200 5500 50  0001 C CNN
F 3 "" H 9200 5500 50  0001 C CNN
	1    9200 5500
	1    0    0    -1  
$EndComp
Wire Wire Line
	9200 5000 9200 5500
$Comp
L R R9
U 1 1 5A9325DE
P 9700 4450
F 0 "R9" V 9800 4450 50  0000 C CNN
F 1 "1k" V 9700 4450 50  0000 C CNN
F 2 "Resistors_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal" V 9630 4450 50  0001 C CNN
F 3 "" H 9700 4450 50  0001 C CNN
	1    9700 4450
	0    1    1    0   
$EndComp
Wire Wire Line
	9900 4900 9900 4450
Wire Wire Line
	9900 4450 9850 4450
$Comp
L R R8
U 1 1 5A9328A6
P 9200 3900
F 0 "R8" H 9300 3900 50  0000 C CNN
F 1 "10k" V 9200 3900 50  0000 C CNN
F 2 "Resistors_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal" V 9130 3900 50  0001 C CNN
F 3 "" H 9200 3900 50  0001 C CNN
	1    9200 3900
	1    0    0    -1  
$EndComp
Wire Wire Line
	9200 3200 9200 3750
Connection ~ 6750 3200
Wire Wire Line
	9200 4050 9200 4800
Wire Wire Line
	8450 4450 9550 4450
Connection ~ 9200 4450
Wire Wire Line
	8450 4850 8450 4450
Wire Notes Line
	5750 4850 8150 4850
Wire Notes Line
	8150 4850 8150 3650
Wire Notes Line
	8150 3650 11150 3650
Wire Notes Line
	11150 3650 11150 6350
Wire Notes Line
	11150 6350 5750 6350
Wire Notes Line
	5750 6350 5750 4850
Text Notes 7050 6200 0    60   ~ 0
Receive circuit. RxD switches polarity at around 8mA through R7.
$Comp
L Mounting_Hole MK3
U 1 1 5A9353BE
P 10700 1100
F 0 "MK3" H 10700 1300 50  0000 C CNN
F 1 "Mounting_Hole" H 10700 1225 50  0000 C CNN
F 2 "Mounting_Holes:MountingHole_4.3mm_M4_ISO14580" H 10700 1100 50  0001 C CNN
F 3 "" H 10700 1100 50  0001 C CNN
	1    10700 1100
	1    0    0    -1  
$EndComp
$Comp
L Mounting_Hole MK1
U 1 1 5A935470
P 10100 1100
F 0 "MK1" H 10100 1300 50  0000 C CNN
F 1 "Mounting_Hole" H 10100 1225 50  0000 C CNN
F 2 "Mounting_Holes:MountingHole_4.3mm_M4_ISO14580" H 10100 1100 50  0001 C CNN
F 3 "" H 10100 1100 50  0001 C CNN
	1    10100 1100
	1    0    0    -1  
$EndComp
$Comp
L Mounting_Hole MK2
U 1 1 5A9354CC
P 10100 1500
F 0 "MK2" H 10100 1700 50  0000 C CNN
F 1 "Mounting_Hole" H 10100 1625 50  0000 C CNN
F 2 "Mounting_Holes:MountingHole_4.3mm_M4_ISO14580" H 10100 1500 50  0001 C CNN
F 3 "" H 10100 1500 50  0001 C CNN
	1    10100 1500
	1    0    0    -1  
$EndComp
$Comp
L Mounting_Hole MK4
U 1 1 5A935545
P 10700 1500
F 0 "MK4" H 10700 1700 50  0000 C CNN
F 1 "Mounting_Hole" H 10700 1625 50  0000 C CNN
F 2 "Mounting_Holes:MountingHole_4.3mm_M4_ISO14580" H 10700 1500 50  0001 C CNN
F 3 "" H 10700 1500 50  0001 C CNN
	1    10700 1500
	1    0    0    -1  
$EndComp
$EndSCHEMATC