External power supplies are separate adapters that power network equipment, mini PCs, IP phones, barcode scanners and other devices that have no internal power supply unit. Our range has over 60 models, including products from Cisco, Dehner, ALLNET and DIGITUS.
How to choose an external power supply
Voltage. The voltage in volts (V) must match exactly what is printed on the device label or in its manual. Too high a voltage can damage the electronics, while too low a voltage will stop the device from working properly.
Current and wattage. The adapter's current in amps (A) must be at least what the device requires, and the wattage is voltage multiplied by current. Leave a little headroom, because an adapter running at its limit gets hotter and wears out sooner.
Connector and polarity. The outer and inner diameters of a barrel plug differ between devices, so the right voltage will not help if the plug does not fit. Also check the centre-pin polarity, shown by a symbol next to the socket. Some devices are powered over USB-C or an Ethernet cable instead.
Form factor. A desktop adapter has a separate mains lead and suits places where the wall socket is hard to reach or crowded. A plug-in adapter goes straight into the socket and needs no extra cable. A PoE injector delivers power and data over a single Ethernet cable.
Certification and protection. Look for the CE mark and protection against short circuit, overload and overheating. This matters most when the adapter runs around the clock, for example with a router or point-of-sale equipment.
Brands in our range
- Cisco: a network equipment maker whose switches, routers and IP phones usually need the power supply specified by the manufacturer.
- ALLNET: a German supplier of network and IoT equipment, with PoE power solutions among its products.
- DIGITUS: known for network cabling, cabinets and other IT accessories, so its power supplies often go alongside that equipment.
- Yealink: a maker of IP phones and video conferencing equipment, with devices powered either by an adapter or over PoE.
- MikroTik and Teltonika: router manufacturers; MikroTik is known for its RouterOS software, while Lithuanian-founded Teltonika builds industrial and mobile-network routers.
- Raspberry Pi and Shuttle: the first makes single-board computers and the second small desktop PCs, both of which need accurate external power specifications.
- Datalogic: a maker of barcode scanners and mobile data collection terminals.
Also in our range: Dehner, Transmedia and Acer.
Frequently asked questions
Can I use a power supply from a different manufacturer?
Yes, provided the voltage is identical, the current is at least as high, and the connector and polarity match. If even one of these differs, do not use the adapter, even if the plug fits. For network equipment and IP phones, the model specified by the manufacturer is the safest choice.
Can I use an adapter with a higher current than stated?
Yes, as long as the voltage and polarity are the same. The device draws only the current it needs, and the figure on the adapter is simply the maximum it can supply. The reverse is not safe: a weaker adapter will overheat and may fail.
What is the difference between a PoE injector and a normal power supply?
A PoE injector sends power over the same Ethernet cable that carries the data, so the device needs no separate power lead. A normal power supply plugs into a dedicated power socket on the device. An injector only works with devices that support PoE, and its wattage must cover what the device needs.
Where do I find the power supply specifications I need?
Voltage, current, wattage and polarity are usually printed on the label of the old adapter or next to the power socket on the device itself. If there is no label, check the manual or the manufacturer's technical specification. When choosing a new adapter, compare all four values.
