Z-Diode ZPY 13
Izmin = 50mA
U=11,4 - 12,7V

NPN-Tr.
BD437
B=50

ua = 12v/1,2A
Ue = 9-17V
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UZ= ua + ube = 12 + 0,7 = 12,7v
ib = ic/b =1,2/50 =24ma
ir = iz+ib=50ma+24ma=74ma
rv=(uv-uz)/ir = 9/74ma = 121
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iz = (uemax - uz)/rv = 17-12,7/121 = 36ma
pvz=12,7*0,4=0,5W
pvr = i^2*r=36ma^2 *121=0,15W

pab = 12v*1,2A = 14,4W
pzu = 17V*(IC+IR)= 17V * ~2A = 34W

Wirkungsgrad:40%