An Add-On Current Limiter For Your PSU

Description: This circuit enables the user to establish a limit on the maximum output current from a power supply unit (PSU). It is particularly beneficial when powering up a project for the first time or conducting a soak test. By setting an upper limit on the current available from the PSU, it safeguards both the power supply and any devices connected to it. This circuit provides a straightforward and cost-effective alternative to a current-limiting power supply.

The current limiting circuit typically employs a combination of resistors, transistors, and operational amplifiers to monitor and control the output current. The core component is often a current sensing resistor placed in series with the load. This resistor generates a small voltage proportional to the current flowing through it. The voltage is then fed to an operational amplifier configured as a comparator.

The operational amplifier compares the sensed voltage with a reference voltage, which is set by a potentiometer. When the sensed voltage exceeds the reference voltage, the operational amplifier output changes state, triggering a transistor or a relay to limit the current. This can be achieved by either reducing the output voltage or disconnecting the load entirely, depending on the design requirements.

Additionally, the circuit may include features such as indicator LEDs to signal when the current limit has been reached, and a reset mechanism to restore normal operation after a fault condition. The use of a heat sink may also be necessary for power components to dissipate heat generated during operation, ensuring reliability and longevity of the circuit.

Overall, this current limiting circuit is essential for protecting sensitive electronics during testing and development phases, providing an economical solution for engineers and hobbyists alike.This circuit allows you to set a limit on the maximum output current available from your PSU. It`s very useful when you power-up a project for the first time - or carry out a soak-test. By setting an upper limit on the current available from your PSU - you can protect both your power supply - and any device connected to it. It offers a simple and cheap alternative to the Current Limiting Power Supply.