Acer K10

A typical projector uses similar technology to most flat-panel TVs, shining a very bright light through what’s effectively a translucent screen.

That bright lamp is usually the projector's major problem, as it typically has a life of only a few thousand hours and is quite fragile. It also makes a typical projector quite large as there has to be sufficient space inside to keep the lamp at a comfortable running temperature. This, combined with the fragility of the lamp itself, makes projectors poor at travelling.

Acer’s K10 projector does away with the lamp, replacing the light source with a bright LED light. LEDs generate very little heat and are more efficient at generating light, but they can't put out nearly as much light as the conventional lamp in a standard projector. A typical one of those will give out between 10 and 20 times more light than the Acer K10 (for those comparing the specifications, the K10 is measured as outputting 100 lumens of brightness).

So you may think it isn’t very bright, but in fact this small projector – its dimensions are 127x122x45mm and it weighs just half a kilogram – manages to throw a usable picture at distances from under one metre up to several metres away, and to generate pictures at sizes up to 1.5m or so, though it worked best with the room lighting dimmed.

Its small case has a VGA socket for computer input and a composite socket for other video and it's powered by a separate power supply, but cleverly it can also take power from many of Acer’s laptop power supplies, so you may be able to share one if you have an Acer laptop.

The K10’s resolution is a non-standard 858x600 pixels, which means it’s not capable of showing high-definition video. It has automatic shape correction to maintain a square picture and the on-screen controls are easy to use, with the buttons set flush into its glossy black surface.

The K10’s noise was surprising: the cooling fan is much smaller than in a conventional projector, but it’s surprisingly noisy, enough to be heard over TV or a DVD.

Given how cheap standard HD projectors are, if portability isn’t a big deal the K10 is not a great choice.