diff --git a/Electrical/Board_003/simulation/mbus_master_004.png b/Electrical/Board_003/simulation/mbus_master_004.png
new file mode 100644
index 00000000..102a1336
Binary files /dev/null and b/Electrical/Board_003/simulation/mbus_master_004.png differ
diff --git a/Electrical/Board_003/simulation/mbus_master_004.qucs-s.sch b/Electrical/Board_003/simulation/mbus_master_004.qucs-s.sch
index 22e233db..f9e13937 100644
--- a/Electrical/Board_003/simulation/mbus_master_004.qucs-s.sch
+++ b/Electrical/Board_003/simulation/mbus_master_004.qucs-s.sch
@@ -1,6 +1,6 @@
 <Qucs Schematic 0.0.20>
 <Properties>
-  <View=146,50,2787,875,0.802424,0,0>
+  <View=146,50,2065,969,0.802424,0,0>
   <Grid=10,10,1>
   <DataSet=mbus_master_004.qucs-s.dat>
   <DataDisplay=mbus_master_004.qucs-s.dpl>
@@ -18,87 +18,88 @@
 <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>
+  <IProbe Pr3 1 460 580 16 -26 1 3>
+  <_BJT BC337AP_2 1 370 420 -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 R8 1 370 320 15 -26 0 1 "6k8" 1 "26.85" 0 "0.0" 0 "0.0" 0 "26.85" 0 "european" 0>
+  <_BJT BC337AP_3 1 500 370 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 R7 1 440 420 -26 15 0 0 "1" 1 "26.85" 0 "0.0" 0 "0.0" 0 "26.85" 0 "european" 0>
+  <IProbe Pr1 1 710 530 -26 16 1 2>
+  <IProbe Pr4 1 640 630 -41 -26 0 3>
+  <R_SPICE R4 1 640 730 15 -26 0 1 "22k" 1 "" 0 "" 0 "" 0 "" 0>
+  <GND * 1 640 800 0 0 0 0>
+  <R R6 1 500 470 15 -26 0 1 "150" 1 "26.85" 0 "0.0" 0 "0.0" 0 "26.85" 0 "european" 0>
+  <Lib D2 1 640 150 -34 6 0 3 "Z-Diodes" 0 "1N5350B" 0>
+  <.DC DC1 1 1100 560 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 SW2 1 1090 670 0 59 0 0 "SW1" 1 "lin" 1 "R5" 1 "1k" 1 "200k" 1 "200" 1 "false" 0>
 </Components>
 <Wires>
   <200 90 200 140 "" 0 0 0 "">
-  <200 90 600 90 "" 0 0 0 "">
+  <200 90 640 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 90 900 110 "mbusplus" 940 70 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 "">
+  <350 670 430 670 "baseq1" 390 720 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 "">
+  <900 190 900 500 "mbusminus" 940 240 14 "">
   <900 190 1010 190 "" 0 0 0 "">
+  <460 610 460 640 "" 0 0 0 "">
+  <460 520 460 550 "" 0 0 0 "">
+  <370 520 460 520 "" 0 0 0 "">
+  <370 450 370 520 "" 0 0 0 "">
+  <370 290 430 290 "" 0 0 0 "">
+  <500 290 500 340 "" 0 0 0 "">
+  <370 350 370 370 "" 0 0 0 "">
+  <370 370 370 390 "" 0 0 0 "">
+  <370 370 470 370 "" 0 0 0 "">
+  <470 420 500 420 "" 0 0 0 "">
+  <400 420 410 420 "" 0 0 0 "">
+  <500 500 500 520 "" 0 0 0 "">
+  <500 420 500 440 "" 0 0 0 "">
+  <500 400 500 420 "" 0 0 0 "">
+  <460 520 500 520 "" 0 0 0 "">
+  <640 530 680 530 "" 0 0 0 "">
+  <740 530 870 530 "pnpbase" 790 480 42 "">
+  <640 530 640 600 "" 0 0 0 "">
+  <640 660 640 700 "" 0 0 0 "">
+  <640 760 640 800 "" 0 0 0 "">
+  <430 290 500 290 "" 0 0 0 "">
+  <430 240 430 290 "" 0 0 0 "">
+  <640 240 640 530 "" 0 0 0 "">
+  <430 240 640 240 "" 0 0 0 "">
+  <640 180 640 240 "" 0 0 0 "">
+  <640 90 900 90 "" 0 0 0 "">
+  <640 90 640 120 "" 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 "" "" "">
+  <Rect 1160 410 820 310 3 #c0c0c0 1 00 1 12 2 34 1 -2.84689 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>
+	<"ngspice/mbus_master_004:v(vdrop)" #ff090d 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.">
+  <Text 500 140 12 #000000 0 "13V 5W 1A\n1N5350B">
+  <Text 1330 520 12 #000000 0 "For TxD high input, voltage drop is constant 12V for any supply voltage between ~13V to 34V\nand for any bus load between 1 to 200k Ohm.">
 </Paintings>