Variable DC Power Supply

A Variable DC Power Supply is one of the most useful tools on the electronics hobbyist's workbench. This circuit is not an absolute novelty, but it's simple, reliable, rugged, and short-proof, featuring variable voltage up to 24V and variable current limiting up to 2A. It's well suited to supply the circuits shown in this website. You can adapt it to your own requirements as explained in the notes below.

The Variable DC Power Supply circuit typically comprises several key components, including a transformer, rectifier, voltage regulator, and current limiting circuitry. The transformer steps down the AC mains voltage to a lower AC voltage, which is then rectified by a bridge rectifier to convert the AC voltage into DC. This rectified voltage can be quite high, so it is often filtered using capacitors to smooth out the voltage ripple.

Next, a voltage regulator is employed to provide a stable output voltage that can be adjusted according to the user's needs. Common voltage regulators used in these circuits include the LM317, which allows for adjustable output voltage through the use of external resistors. The output voltage can be varied from 1.25V to 24V by selecting appropriate resistor values, making it versatile for different applications.

Current limiting is an essential feature for protecting both the power supply and the connected load. This can be implemented using a simple resistor in series with the load, or through more sophisticated methods such as using a current sensing resistor and operational amplifiers to provide feedback to the regulator. This ensures that the output current does not exceed the specified limit, which in this case is set to 2A.

The design of the power supply should also consider heat dissipation, as the voltage regulator may generate significant heat, especially under high load conditions. Adequate heat sinking is necessary to ensure the reliability and longevity of the components. Additionally, incorporating fuses or circuit breakers can provide further protection against short circuits and overload conditions.

Overall, the variable DC power supply circuit is a fundamental tool for electronics enthusiasts, offering flexibility and adaptability for a wide range of projects and experiments.A Variable DC Power Supply is one of the most useful tools on the electronics hobbyist`s workbench. This circuit is not an absolute novelty, but it`s simple, reliable, "rugged" and short-proof, featuring variable voltage up to 24V and variable current limiting up to 2A. It`s well suited to supply the circuits shown in this website. You can adapt it to your own requirements as explained in the notes below. 🔗 External reference