Zener Diode circuit design Calculator
This CalcTown calculator calculates the Input Resistance (Ri) in a Zener Diode voltage regulator circuit so that the designed specifications of input voltage and load resistance can be met.
*Please note that it has been assumed that the minimum Zener Current is 10% of the maximum Zener Current. Although in more practical applications, it is usually 20-30%.
**Out of the two resistance values shown in the output, please choose the one with lower magnitude and neglect the higher value.
Zener Diode circuit design Calculator

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where
VPS = Voltage of the Power Source
IL = Current Flowing through the Load Resistance
IZ = Current Flowing through the Zener Diode
VZ = Zener Voltage
IZ(max)= Maximum Zener Current
and Load Resistance and Power Source Voltage are variable over a certain range.