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Saturday, June 1, 2024

How to make a multi voltage power supply without a transformer


 How to make a multi voltage power supply without a transformer

For low powers, we can do without the transformer and the traditional diode bridge or the switching power supply. Much more economical solutions exist if you only want a few mA. Indeed, a transformer or a MOSFET/inductor/regulator assembly are expensive and bulky. They can be more expensive than the rest of the circuit to power!


Non-isolated transformerless power supplies offer low cost and are a very interesting alternative. There are 2 types of power supply:

a) resistive power supply

b) capacitive power supply


A capacitive power supply is also called a “dropping capacitive power supply”. The “capa chutrice” reflects the idea that the voltage drop occurs across the “capa”. “Capa” is a (rather ugly?) abbreviation of “capacitance”, therefore “capacitor” by abuse of language (metonymy).


This article presents capacitive power supply (therefore without transformer). Resistive power supply is presented in another article.


 How to make a multi voltage power supply without a transformer

For low powers, we can do without the transformer and the traditional diode bridge or the switching power supply. Much more economical solutions exist if you only want a few mA. Indeed, a transformer or a MOSFET/inductor/regulator assembly are expensive and bulky. They can be more expensive than the rest of the circuit to power!


Non-isolated transformerless power supplies offer low cost and are a very interesting alternative. There are 2 types of power supply:

a) resistive power supply

b) capacitive power supply


A capacitive power supply is also called a “dropping capacitive power supply”. The “capa chutrice” reflects the idea that the voltage drop occurs across the “capa”. “Capa” is a (rather ugly?) abbreviation of “capacitance”, therefore “capacitor” by abuse of language (metonymy).


This article presents capacitive power supply (therefore without transformer). Resistive power supply is presented in another article.

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