diff --git a/Electrical/Board_003/simulation/mbus_master_004.qucs-s.dpl b/Electrical/Board_003/simulation/mbus_master_004.qucs-s.dpl
new file mode 100644
index 00000000..241e6f01
--- /dev/null
+++ b/Electrical/Board_003/simulation/mbus_master_004.qucs-s.dpl
@@ -0,0 +1,33 @@
+<Qucs Schematic 0.0.20>
+<Properties>
+  <View=0,-1080,1119,3261,1,0,0>
+  <Grid=10,10,0>
+  <DataSet=mbus_master_004.qucs-s.dat>
+  <DataDisplay=mbus_master_004.qucs-s.sch>
+  <OpenDisplay=1>
+  <Script=mbus_master_004.qucs-s.m>
+  <RunScript=0>
+  <showFrame=0>
+  <FrameText0=Title>
+  <FrameText1=Drawn By:>
+  <FrameText2=Date:>
+  <FrameText3=Revision:>
+</Properties>
+<Symbol>
+</Symbol>
+<Components>
+</Components>
+<Wires>
+</Wires>
+<Diagrams>
+  <Rect 140 -826 936 194 3 #c0c0c0 1 00 1 12 2 34 1 -0.00203476 0.01 0.0223864 1 -1 0.5 1 315 0 225 "" "" "">
+	<"ngspice/mbus_master_004:i(pr1)" #0000ff 0 3 0 0 0>
+	<"ngspice/mbus_master_004:i(pr2)" #ff0000 0 3 0 0 0>
+	<"ngspice/mbus_master_004:i(pr4)" #00ff00 0 3 0 0 0>
+  </Rect>
+  <Rect 140 -609 937 161 3 #c0c0c0 1 00 1 12 2 34 1 -0.00203476 0.01 0.0223864 1 -1 0.5 1 315 0 225 "" "" "">
+	<"ngspice/mbus_master_004:i(pr3)" #ff00ff 0 3 0 0 0>
+  </Rect>
+</Diagrams>
+<Paintings>
+</Paintings>
diff --git a/Electrical/Board_003/simulation/mbus_master_004.qucs-s.sch b/Electrical/Board_003/simulation/mbus_master_004.qucs-s.sch
new file mode 100644
index 00000000..22e233db
--- /dev/null
+++ b/Electrical/Board_003/simulation/mbus_master_004.qucs-s.sch
@@ -0,0 +1,104 @@
+<Qucs Schematic 0.0.20>
+<Properties>
+  <View=146,50,2787,875,0.802424,0,0>
+  <Grid=10,10,1>
+  <DataSet=mbus_master_004.qucs-s.dat>
+  <DataDisplay=mbus_master_004.qucs-s.dpl>
+  <OpenDisplay=1>
+  <Script=mbus_master_004.qucs-s.m>
+  <RunScript=0>
+  <showFrame=0>
+  <FrameText0=Title>
+  <FrameText1=Drawn By:>
+  <FrameText2=Date:>
+  <FrameText3=Revision:>
+</Properties>
+<Symbol>
+</Symbol>
+<Components>
+  <GND * 1 200 230 0 0 0 0>
+  <Vdc V1 1 200 170 18 -26 0 1 "34 V" 1>
+  <Lib D1 1 600 140 -34 6 0 3 "Z-Diodes" 0 "1N5348B" 0>
+  <R_SPICE R5 1 900 150 15 -26 0 1 "220k" 1 "" 0 "" 0 "" 0 "" 0>
+  <.TR TR1 1 1330 650 0 61 0 0 "lin" 1 "0" 1 "5 ms" 1 "101" 0 "Trapezoidal" 0 "2" 0 "1 ns" 0 "1e-16" 0 "150" 0 "0.001" 0 "1 pA" 0 "1 uV" 0 "26.85" 0 "1e-3" 0 "1e-6" 0 "1" 0 "CroutLU" 0 "no" 0 "yes" 0 "0" 0>
+  <.DC DC1 1 1120 610 0 38 0 0 "26.85" 0 "0.001" 0 "1 pA" 0 "1 uV" 0 "no" 0 "150" 0 "no" 0 "none" 0 "CroutLU" 0>
+  <.SW SW1 1 1540 630 0 59 0 0 "DC1" 1 "lin" 1 "V1" 1 "34V" 1 "12V" 1 "111" 1 "false" 0>
+  <GND * 1 200 800 0 0 0 0>
+  <GND * 1 460 800 0 0 0 0>
+  <GND * 1 600 800 0 0 0 0>
+  <GND * 1 900 810 0 0 0 0>
+  <IProbe Pr2 1 900 660 16 -26 1 3>
+  <R_SPICE R4 1 600 720 15 -26 0 1 "22k" 1 "" 0 "" 0 "" 0 "" 0>
+  <IProbe Pr4 1 600 630 -41 -26 0 3>
+  <Vdc V3 1 200 740 18 -26 0 1 "5 V" 1>
+  <_BJT BC337AP_1 1 460 670 8 -26 0 0 "npn" 0 "3.94e-14" 0 "1" 0 "0.974" 0 "0.8" 0 "0.1" 0 "109.4" 0 "14.25" 0 "7.4e-15" 0 "1.3" 0 "3.16e-13" 0 "1.2" 0 "175" 0 "20.5" 0 "0" 0 "0" 0 "0.0539" 0 "0.1259" 0 "1.1" 0 "6.3e-11" 0 "0.75" 0 "0.33" 0 "1.58e-11" 0 "0.505" 0 "0.39" 0 "1" 0 "0" 0 "0.75" 0 "0" 0 "0.5" 0 "7.5e-10" 0 "0" 0 "0" 0 "0" 0 "8.5e-08" 0 "26.85" 0 "0" 0 "1" 0 "1" 0 "0" 0 "1" 0 "1" 0 "0" 0 "0" 0 "3" 0 "1.11" 0 "26.85" 0 "1" 0>
+  <R R1 1 320 670 -26 15 0 0 "1k" 1 "26.85" 0 "0.0" 0 "0.0" 0 "26.85" 0 "european" 0>
+  <_BJT BD136_138_140_1 1 900 530 8 -26 1 0 "pnp" 0 "2.9537e-13" 0 "1" 0 "1.021" 0 "1.0993" 0 "0.1" 0 "137" 0 "8.41" 0 "1.8002e-13" 0 "1.5" 0 "7.0433e-12" 0 "1.38" 0 "201.4" 0 "23.765" 0 "0.01" 0 "0.011" 0 "0.01" 0 "0.1109" 0 "1.98" 0 "2.1982e-10" 0 "0.7211" 0 "0.3685" 0 "6.8291e-11" 0 "0.5499" 0 "0.3668" 0 "0.5287" 0 "0" 0 "0.75" 0 "0" 0 "0.5" 0 "0" 0 "0" 0 "0" 0 "0" 0 "0" 0 "26.85" 0 "0" 0 "1" 0 "1" 0 "0" 0 "1" 0 "1" 0 "0" 0 "1.4883" 0 "3" 0 "1.2343" 0 "26.85" 0 "1" 0>
+  <IProbe Pr1 1 700 530 -26 16 1 2>
+  <IProbe Pr3 1 600 480 16 -26 1 3>
+  <_BJT BC337AP_3 1 650 280 8 -26 0 0 "npn" 0 "3.94e-14" 0 "1" 0 "0.974" 0 "0.8" 0 "0.1" 0 "109.4" 0 "14.25" 0 "7.4e-15" 0 "1.3" 0 "3.16e-13" 0 "1.2" 0 "175" 0 "20.5" 0 "0" 0 "0" 0 "0.0539" 0 "0.1259" 0 "1.1" 0 "6.3e-11" 0 "0.75" 0 "0.33" 0 "1.58e-11" 0 "0.505" 0 "0.39" 0 "1" 0 "0" 0 "0.75" 0 "0" 0 "0.5" 0 "7.5e-10" 0 "0" 0 "0" 0 "0" 0 "8.5e-08" 0 "26.85" 0 "0" 0 "1" 0 "1" 0 "0" 0 "1" 0 "1" 0 "0" 0 "0" 0 "3" 0 "1.11" 0 "26.85" 0 "1" 0>
+  <_BJT BC337AP_2 1 520 330 -96 -26 1 2 "npn" 0 "3.94e-14" 0 "1" 0 "0.974" 0 "0.8" 0 "0.1" 0 "109.4" 0 "14.25" 0 "7.4e-15" 0 "1.3" 0 "3.16e-13" 0 "1.2" 0 "175" 0 "20.5" 0 "0" 0 "0" 0 "0.0539" 0 "0.1259" 0 "1.1" 0 "6.3e-11" 0 "0.75" 0 "0.33" 0 "1.58e-11" 0 "0.505" 0 "0.39" 0 "1" 0 "0" 0 "0.75" 0 "0" 0 "0.5" 0 "7.5e-10" 0 "0" 0 "0" 0 "0" 0 "8.5e-08" 0 "26.85" 0 "0" 0 "1" 0 "1" 0 "0" 0 "1" 0 "1" 0 "0" 0 "0" 0 "3" 0 "1.11" 0 "26.85" 0 "1" 0>
+  <R R7 1 600 330 -26 15 0 0 "1" 1 "26.85" 0 "0.0" 0 "0.0" 0 "26.85" 0 "european" 0>
+  <R R6 1 650 380 15 -26 0 1 "39" 1 "26.85" 0 "0.0" 0 "0.0" 0 "26.85" 0 "european" 0>
+  <R R8 1 520 230 15 -26 0 1 "6k8" 1 "26.85" 0 "0.0" 0 "0.0" 0 "26.85" 0 "european" 0>
+  <NutmegEq NutmegEq1 1 1790 630 -27 15 0 0 "tran" 1 "mbusdiff=v(mbusplus)-v(mbusminus)" 1>
+  <VProbe Vdrop 1 1030 160 -16 28 0 3>
+</Components>
+<Wires>
+  <200 90 200 140 "" 0 0 0 "">
+  <200 90 600 90 "" 0 0 0 "">
+  <200 200 200 230 "" 0 0 0 "">
+  <600 90 600 110 "" 0 0 0 "">
+  <600 90 900 90 "" 0 0 0 "">
+  <900 90 900 110 "mbusplus" 990 100 10 "">
+  <900 690 900 810 "" 0 0 0 "">
+  <600 750 600 800 "" 0 0 0 "">
+  <600 660 600 690 "" 0 0 0 "">
+  <200 770 200 800 "" 0 0 0 "">
+  <460 700 460 800 "" 0 0 0 "">
+  <350 670 430 670 "baseq1" 370 610 42 "">
+  <200 670 200 710 "" 0 0 0 "">
+  <200 670 290 670 "TxD" 220 610 56 "">
+  <900 180 900 190 "" 0 0 0 "">
+  <900 560 900 630 "" 0 0 0 "">
+  <730 530 870 530 "pnpbase" 790 480 52 "">
+  <600 530 600 600 "" 0 0 0 "">
+  <600 530 670 530 "" 0 0 0 "">
+  <460 530 460 640 "" 0 0 0 "">
+  <460 530 600 530 "" 0 0 0 "">
+  <600 510 600 530 "" 0 0 0 "">
+  <650 310 650 330 "" 0 0 0 "">
+  <520 280 620 280 "" 0 0 0 "">
+  <520 280 520 300 "" 0 0 0 "">
+  <550 330 570 330 "" 0 0 0 "">
+  <630 330 650 330 "" 0 0 0 "">
+  <650 330 650 350 "" 0 0 0 "">
+  <650 200 650 250 "" 0 0 0 "">
+  <520 200 600 200 "" 0 0 0 "">
+  <520 260 520 280 "" 0 0 0 "">
+  <600 200 650 200 "" 0 0 0 "">
+  <600 170 600 200 "" 0 0 0 "">
+  <650 410 650 430 "" 0 0 0 "">
+  <520 360 520 430 "" 0 0 0 "">
+  <520 430 600 430 "" 0 0 0 "">
+  <600 430 650 430 "" 0 0 0 "">
+  <600 430 600 450 "" 0 0 0 "">
+  <1010 110 1010 150 "" 0 0 0 "">
+  <900 110 900 120 "" 0 0 0 "">
+  <900 110 1010 110 "" 0 0 0 "">
+  <1010 170 1010 190 "" 0 0 0 "">
+  <900 190 900 500 "mbusminus" 980 200 14 "">
+  <900 190 1010 190 "" 0 0 0 "">
+</Wires>
+<Diagrams>
+  <Rect 1920 450 820 310 3 #c0c0c0 1 00 1 12 2 34 1 -1.71063 10 40 1 -1 0.5 1 315 0 225 "" "" "">
+	<"ngspice/mbus_master_004:v(mbusplus)" #00ff00 0 3 0 0 0>
+	<"ngspice/mbus_master_004:v(mbusminus)" #00ffff 0 3 0 0 0>
+	<"ngspice/mbus_master_004:v(pnpbase)" #ffff00 0 3 0 0 0>
+  </Rect>
+</Diagrams>
+<Paintings>
+  <Text 470 140 12 #000000 0 "11V 5W 1A">
+  <Text 1210 90 12 #000000 0 "Similar to mbus_master_002 but using a zener instead of R2.\n">
+  <Text 1330 530 12 #000000 0 "With a zener the voltage drop is constantly 12V like it should be.">
+</Paintings>