Electronic – Regular (not Zener) Diode as Voltage Regulator

diodesvoltage-regulator

I see a lot of information regarding Zener diode voltage regulators but how about a regular diode voltage regulator?

What would be the potential drawbacks of using something like this on the picture below:

schematic

simulate this circuit – Schematic created using CircuitLab

Where Rload should get whatever voltage is across the 1N4001 or whatever diode we use?

Best Answer

  1. The choice of voltages is very limited. For a silicon diode it will be around 700 mV.
  2. The voltage is not well regulated. The forward voltage of a diode is reasonably invariant with current over some range, but it's not as good as most zeners.
  3. The temperature dependency will be higher. This is particularly compared to a zener roughly in the 6 to 6.5 V range. There are two opposite temperature effects that cross over at about that voltage, reducing the overall temperature dependence.

One place where a diode as a shunt regulator can be useful is when you want to generate a voltage that offsets another diode or the B-E drop of a bipolar transistor. In that case the temperature dependency can actually be beneficial.

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