series vs shunt linear voltage regulator

138

01:47:17

Why doesnt it work as it should?

published 4 years ago

Robert_Kidd

4 years ago

In your top circuit you only have 9V so your 10V reference zener diode will not conduct significantly. Note that in EC the default zener current is (a rather odd) 13.6mA. Adjust the 100 Ohm to 88 Ohm to achieve this. In a real circuit you would refer to the data sheet for the particular zener type you are using.

Robert_Kidd

4 years ago

Adjust the input voltage to, say, 20V.

Robert_Kidd

4 years ago

In your lower circuit, increase voltage input to, say, 20V. In this case change the zener resistor to 680 Ohm. Not that output voltage will be approximately 0.7V less than the zener voltage due to the base-emitter drop. Hope this helps.

bricekrispies5958

4 years ago

Thanks Robert

Robert_Kidd

4 years ago

You’re welcome.

eroleken

4 years ago

Hi can u explain the role of trasnsistor here?

Robert_Kidd

4 years ago

Hello! Yes, the zener holds the transistor base at 10V. With a load applied the transistor will conduct. As it’s base is held constant by the zener, the transistor conducts giving you a nominally constant voltage at its emitter which is one PN junction drop less than the zener voltage.

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