External Power Supplies

eiodotcom —  October 3, 2012 — Leave a comment

Today’s EIO post is on external power supplies.

 

 

External Power Supplies 101

 

External power supplies are devices that convert ac power from a wall outlet into lower voltage dc or ac power to be used directly by electronic circuits. External power supplies come in a separate physical enclosure than the end-use product, and usually provide power to the device directly through a separate cord and plug. External power supplies are used to power a variety of electronic devices, including: laptop computers, printers, cordless phones, cell phones, etc.

 

External power supplies are used both with equipment with no other source of power, and with battery-powered equipment, where the supply both charges the battery and powers the equipment when plugged in. One of the benefits of using an external, rather than internal power supply is it increases the portability of a device, by avoiding the need of internal power components. Use of an external power supply allows portability of battery-powered equipment without the added bulk of internal power components and makes it unnecessary to produce equipment for use only with a specified power source.

 

Benefits of Using an External Power Supply

Safety — External power adapters can free product designers from worrying about some safety issues. Much of this style of equipment uses only voltages low enough not to be a safety hazard internally, although the power supply must out of necessity use dangerous mains voltage. If an external power supply is used (usually via a power connector, often of coaxial type), the equipment need not be designed with concern for hazardous voltages inside the enclosure. This is particularly relevant for equipment with lightweight cases which may break and expose internal electrical parts.

Heat reduction — Heat reduces reliability and longevity of electronic components, and can cause sensitive circuits to become inaccurate or malfunction. A separate power supply removes a source of heat from the apparatus.

Electrical noise reduction — Because radiated electrical noise falls off with the square of the distance, it is to the manufacturer’s advantage to convert potentially noisy AC line power or automotive power to “clean”, filtered DC in an external adapter, at a safe distance from noise-sensitive circuitry.

Weight and size reduction — When most power adapters featured simple mains-frequency transformer-based designs, they were quite heavy and large, and added considerably to the weight and bulk of devices designed to be lightweight. Even modern power supplies are relatively heavy compared to other circuitry. Removing power components from equipment powered by rechargeable batteries reduces the weight and size which must be carried, though use of other rechargeable batteries like sealed lead-acid batteries can questionably put more weight on the equipment.

Ease of replacement — Power supplies are more prone to failure than other circuitry due to their exposure to power spikes and their internal generation of waste heat. External power supplies can be replaced quickly by a user without the need to have the powered device repaired.

Configuration versatility — Externally powered electronic products can be used with different power sources as needed (e.g. 120VAC, 240VAC, 12VDC, or external battery pack), for convenient use in the field, or when traveling.

Some of Our Products  (To see all power supply products, click here)

 

 

Velleman PSSMV7U COMPACT SWITCHING POWER SUPPLY 36W WITH SELECTABLE OUTPUT

 

Brand Velleman
Model PSSMV7U
Specifications
Supply Voltage 100 ~ 240V AC
Power 36W
Efficiency >=70%
Selectable Outputs 5 to 24V DC in steps of 1V (from 4.3 to 1.5A)
Output Plugs 2.5mm mono, 3.5mm mono, 1.0×3.0mm, 1.35×3.5mm, 1.7×4.0mm, 2.1×5.0mm, 2.5×5.5mm, 1.5×5.5mm
Dimensions 3.5″ x 1.8″ x 1.2″
Features
Features
  • with 8 detachable DC plugs
  • for notebook computers & personal digital electronic devices
  • stabilized output, low ripple & interference
  • short-circuit & overload protection
  • high efficiency & low energy consumption

 

 

 

 

 

 

VELLEMAN PSSMV3 COMPACT SWITCHING POWER SUPPLY 24W WITH SELECTABLE OUTPUT

 

This switch mode regulated power supply wall adapter comes with 4 input plugs to operate around the world. Includes input power plugs for the US, UK, Europe, Taiwan, and China! Additionally, choose from 7 different DC output connectors. Finally, a switching power supply adapter with a user selectable output plug size and polarity!

Get rid of those bulky power-hungry heat-producing linear power adapters. These switching power adaptors are state-of-the-art switch mode power supplies featuring major advantages such as:
– cooler running
– stabilized (regulated) output
– short-circuit and overload protection
– compact design
– very low idling power consumption
– multiple (selectable) voltage outputs
– user configurable output connector polarity: center (+)  or  center (-)
– world wide AC input voltage range

Features

  • 4 AC input power plug configurations included (user selectable)
    • AC plugs to fit in US, UK, Europe, Taiwan and China
  • compact switch mode regulated power supply design is light-weight and efficient

Specifications

  • AC input supply voltage: 100 ~ 240V AC, 50/60 Hz
  • output power: 24.0 watts max.
  • efficiency: > = 70%
  • user selectable output voltages:
    • 3V,  4.5V,  6V, 7.5V, 9V, and 12V DC
  • output current: 2,000ma (2 amps) maximum current consumption
  • 7 DC output connector plugs included (user selectable)
    • 2.5mm (male)
    • 3.5mm (male)
    • 2.35×0.75mm (female)
    • 3.5×1.35mm (female)
    • 4.0×1.7mm (female)
    • 5.0×2.1mm (female)
    • 5.5×2.5mm (female)
  • power supply dimensions: 4.6″ x 2.4″ x 3.3″  (11.6cm x 6.1cm x 8.3cm)

 

 

 

 

VELLEMAN PSSMV1USA COMPACT SWITCHING POWER SUPPLY 10W WITH SELECTABLE OUTPUT

 

Brand Velleman
Model PSSMV1USA
Specifications
Supply Voltage 100 ~ 230V AC ± 15%
Power 10W
Efficiency > 80%
Output Voltages 3, 4.5, 6, 7.5, 9, 12V DC
Output Current 800mA (regulated) / 1.5A max.
Plugs 2.5mm mono, 3.5mm mono, 1.0×3.0mm, 1.35×3.5mm, 1.7×4.0mm, 2.1×5.0mm, 2.5×5.5mm, 1.5×5.5mm
Dimensions 2.6″ x 1.1″ x 2.9″
Weight 3.0 oz
Features
Features Get rid of those bulky power-hungry heat-producing mains adapters.
These adaptors use state-of-the-art switching power supplies and feature some major advantages such as:
– cooler running
– stabilized output
– short-circuit and overload protection
– compact design
– very low idling consumption
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