Different Types of DC Power Supply and their Applications

Oct. 09, 2022

There are several types of DC power supply on the market. In this chapter, some of the most common types and their applications will be discussed briefly.

Battery Eliminator

Battery eliminators are the cheapest among DC power supplies and have a compact design. As the name suggests, they serve the functions of a battery whenever one is not available. Battery eliminators are typically used on battery-operated equipment.

Some battery eliminators can provide 18V DC power to devices normally powered by automobile batteries. These units can also be used in CB radios and automotive stereo systems.

Battery eliminators typically have an on-off switch and a rotary switch, which you can turn to select the target output DC voltage. For instance, there are units with outputs of 1.5-6V (with increments of 1.5V), 9V, and 12V. These are designed such that operations in a dead short can be done safely and continuously.

Constant Voltage Supply

A constant voltage supply provides a constant and adjustable voltage. Its design is much more complex than battery eliminators.

A typical unit has a voltage meter and current meter where you can monitor the voltage and current supply values respectively.

Regardless of the load‘s resistance, the voltage is maintained in this type of DC power supply.

The output voltage is adjusted using a knob. For some units, the output voltage may not be adjusted down to zero volts. Also, some models do not supply the rated current at any output voltage. In these instances, the maximum output current would be proportional to the output voltage.

Some models also provide tie points, with a current limit, to provide connections to an external digital meter (for accurate monitoring of output voltage) or other circuits.

constant voltage supply

Constant Voltage/Constant Current Supply

A constant voltage/constant current supply, the widely used lab power supply, allows a constant supply of both voltage and current.

Regardless of the load‘s resistance, the current is maintained in this type of DC power supply when in constant current mode.

Typical units include one adjustable voltage and fine and coarse controls for both voltage and current supply. In some models, 10-turn pots, thumbwheel switches, or pushbutton switches are used instead for adjustment. A meter is not necessary when using thumbwheel and pushbutton switches with accurate settings.

This type of DC power supply has the following features:

Remote Sensing

The voltage of the load can be measured using a high-impedance input. The power supply performs corrections for the voltage drop in the leads, bridging the supply to the load.

Master/Slave Connections

Power supplies from the same family can be connected in parallel or series using different methods to generate higher voltages or currents.

Remote Programming Terminal

Input terminals for a voltage or resistance are present in some power supplies that are used to control output voltage/current.

Multiple Output Supply

As the name suggests, this type of DC power supply provides more than one DC output, usually two or three.

Multiple output supplies are cost-effective option systems requiring multiple voltages.

Multiple Output Supply

For example, a triple output supply is used in circuit development:

1. Digital Logic

where one output provides 0-6V

2. Bipolar Analog Circuitry

where the other two supply outputs provide 0-20V.

A knob or keypad is placed to set the three outputs independently i.e., turning on and off the outputs can be done separately or all at once. This feature allows a whole printed circuit board to be powered up.

A typical unit also has features like:

3. Output Operation Timer

This allows the user to set a time interval in which the output can turn off automatically after the time set has passed.

3. Voltage Limit for All Channels

The user can set a voltage limit to avoid accidental over-voltage settings in their prototype electrical design project.

4. Series or Parallel Connection

A higher voltage or current can be achieved by connecting two volt channels in series or parallel.

5. Storage Registers

This allows the user to save 50 instrument states for easy recollection of data in repetitive testing.

6. Last Power-On Settings

In case the AC mains line fails, this type of power supply will restart when the AC power restarts, then provide the same output as the last power-on settings.

Programmable Supply

Programmable supply, often known as system power supplies, are normally integrated into a computer-operated system during production or testing.

Multi-Range Supply

A multi-range DC power supply allows various combinations of voltage and current to operate and still provide maximum power. This is in contrast with most common power supplies that can only provide a maximum output power if operated at a certain fixed voltage and current ratings. Hence, the output power will be less than the maximum if other voltages/current combinations are used in conventional power supplies.

The main advantages of multi-range supply include:

Flexibility in output ratings
Savings in cost and bench space
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