home :: power supply :: dc power supply :: build a symmetrical power supply: ±125v to ±30v 1a circuit

Description

This text describes a voltage converter designed to transform a voltage range of ±1.25-30V from an input of ±35V. A three-terminal regulator is employed for this voltage modification. Specifically, the LM317 is utilized for the positive voltage output, while the LM337 is used for the negative voltage. The resulting output current capability reaches 1 Ampere. A crucial element in this unit’s design is the radiator, or heatsink, associated with the regulator. Without a sufficient heatsink, the regulator will overheat and fail due to the heat generated when supplying 1 Ampere of electric current. The advantage of this type of regulator lies in its minimal noise generation and reduced component count. However, its conversion efficiency is a notable drawback, typically falling below 42% when transforming from 35V to 5V. More recently, switching regulators have become increasingly affordable. Although they necessitate a slightly larger number of parts, they offer superior efficiency, particularly when handling outputs of over 1A at voltages above 15V, or 0.4A at voltages below 15V. Adjustments are made using RV1-2 to fine-tune each individual output voltage (+V or -V), and RV3 for dual outputs. Monitoring is accomplished through S1, selecting the voltmeter V1 for observation.

Integrated Circuits (ICs) play a pivotal role in this circuit's functionality. Integrated circuits, or ICs, are complex semiconductor devices that combine multiple electronic components into a single package. They are fundamental to modern electronics due to their compact size, reduced power consumption, and improved reliability. The LM317 and LM337 are examples of linear voltage regulators, a specialized type of IC designed to maintain a constant output voltage regardless of variations in input voltage or load current. These regulators operate based on the principle of dissipating excess power as heat, which is a characteristic of linear regulators. The LM317 is a three-terminal adjustable positive voltage regulator, meaning its output voltage can be precisely set using external resistors. The LM337 is a three-terminal adjustable negative voltage regulator, mirroring the LM317's functionality for negative voltage output. These regulators are commonly employed in power supply circuits, battery charging systems, and other applications where stable voltage regulation is required. Their performance characteristics, such as quiescent current (the current drawn by the regulator when no load is connected) and temperature stability, are key factors in determining their suitability for a given application. Moreover, the operational characteristics are heavily influenced by the ambient temperature surrounding the ICs. Therefore, efficient heat dissipation is paramount for reliable operation.

Circuit diagram

Part List