diff --git a/Electrical/Board_003/simulation/current_limit.png b/Electrical/Board_003/simulation/current_limit.png
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Binary files /dev/null and b/Electrical/Board_003/simulation/current_limit.png differ
diff --git a/Electrical/Board_003/simulation/current_limit.qucs-s.dpl b/Electrical/Board_003/simulation/current_limit.qucs-s.dpl
new file mode 100644
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diff --git a/Electrical/Board_003/simulation/current_limit.qucs-s.sch b/Electrical/Board_003/simulation/current_limit.qucs-s.sch
new file mode 100644
index 00000000..c59c7b9c
--- /dev/null
+++ b/Electrical/Board_003/simulation/current_limit.qucs-s.sch
@@ -0,0 +1,69 @@
+<Qucs Schematic 0.0.20>
+<Properties>
+  <View=0,-200,2138,800,1,0,0>
+  <Grid=10,10,1>
+  <DataSet=current_limit.qucs-s.dat>
+  <DataDisplay=current_limit.qucs-s.dpl>
+  <OpenDisplay=1>
+  <Script=current_limit.qucs-s.m>
+  <RunScript=0>
+  <showFrame=0>
+  <FrameText0=Title>
+  <FrameText1=Drawn By:>
+  <FrameText2=Date:>
+  <FrameText3=Revision:>
+</Properties>
+<Symbol>
+</Symbol>
+<Components>
+  <_BJT BC337AP_2 1 280 210 -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>
+  <_BJT BC337AP_1 1 500 150 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>
+  <GND * 1 500 440 0 0 0 0>
+  <GND * 1 280 440 0 0 0 0>
+  <R R1 1 500 50 15 -26 0 1 "0" 1 "26.85" 0 "0.0" 0 "0.0" 0 "26.85" 0 "european" 0>
+  <IProbe Pr1 1 500 270 -41 -26 0 3>
+  <IProbe Pr2 1 280 330 -41 -26 0 3>
+  <Lib D1 1 500 -90 -34 6 0 3 "Z-Diodes" 0 "1N759" 0>
+  <Vdc V1 1 80 -50 18 -26 0 1 "34 V" 1>
+  <GND * 1 80 20 0 0 0 0>
+  <.DC DC1 1 30 360 0 37 0 0 "26.85" 0 "0.001" 0 "1 pA" 0 "1 uV" 0 "no" 0 "150" 0 "no" 0 "none" 0 "CroutLU" 0>
+  <R R3 1 390 210 -26 15 0 0 "1" 1 "26.85" 0 "0.0" 0 "0.0" 0 "26.85" 0 "european" 0>
+  <R R2 1 280 90 15 -26 0 1 "6k8" 1 "26.85" 0 "0.0" 0 "0.0" 0 "26.85" 0 "european" 0>
+  <.SW SW2 1 650 230 0 59 0 0 "DC1" 1 "lin" 1 "V1" 1 "20V" 1 "40V" 1 "21" 1 "false" 0>
+  <IProbe Pr3 1 230 -150 -26 16 0 0>
+  <.SW SW1 0 30 110 0 59 0 0 "DC1" 1 "lin" 1 "R4" 1 "30 Ohm" 1 "47 Ohm" 1 "50" 1 "false" 0>
+  <R R4 1 500 370 15 -26 0 1 "39" 1 "26.85" 0 "0.0" 0 "0.0" 0 "26.85" 0 "european" 0>
+</Components>
+<Wires>
+  <500 80 500 120 "" 0 0 0 "">
+  <500 180 500 210 "" 0 0 0 "">
+  <310 210 360 210 "" 0 0 0 "">
+  <420 210 500 210 "" 0 0 0 "">
+  <280 120 280 150 "" 0 0 0 "">
+  <280 150 280 180 "" 0 0 0 "">
+  <280 150 470 150 "" 0 0 0 "">
+  <500 400 500 440 "" 0 0 0 "">
+  <280 -20 280 60 "" 0 0 0 "">
+  <500 -20 500 20 "out" 530 -40 9 "">
+  <280 -20 500 -20 "" 0 0 0 "">
+  <500 210 500 240 "" 0 0 0 "">
+  <500 300 500 340 "" 0 0 0 "">
+  <280 240 280 300 "" 0 0 0 "">
+  <280 360 280 440 "" 0 0 0 "">
+  <500 -60 500 -20 "" 0 0 0 "">
+  <80 -20 80 20 "" 0 0 0 "">
+  <80 -150 80 -80 "" 0 0 0 "">
+  <80 -150 200 -150 "" 0 0 0 "">
+  <500 -150 500 -120 "" 0 0 0 "">
+  <260 -150 500 -150 "" 0 0 0 "">
+  <500 -150 500 -150 "in" 530 -180 0 "">
+</Wires>
+<Diagrams>
+  <Rect 760 67 693 187 3 #c0c0c0 1 00 1 0 10 40 1 0 20 42.1552 1 -1 1 1 315 0 225 "" "" "">
+	<"ngspice/current_limit:v(in)" #0000ff 0 3 0 0 0>
+	<"ngspice/current_limit:v(out)" #ff0000 0 3 0 0 0>
+  </Rect>
+</Diagrams>
+<Paintings>
+  <Text 820 140 12 #000000 0 "With the zener diode, the output is constantly 12V below the input voltage.\nAnd with the current limiting circuit, the load is always 20mA.\n\nhttps://en.wikipedia.org/wiki/Current_limiting#Single_power-supply_circuits\nhttps://electronics.stackexchange.com/questions/39465/current-limiters-using-transistors-and-diodes\n">
+</Paintings>