by Damien Gayle Daily Mail
A back garden inventor has published details on how an old-style big screen television can be converted into a solar-powered death ray that burns at 2,000F.
Grant Thompson, the self-styled King of Random, has made two YouTube videos which show how the screens of old rear-projection TVs can be used to condense sunlight into point capable of melting coins.
The incredible films show him using such a screen mounted on to a wooden frame to burns holes through concrete, boil water in seconds and incinerate planks of wood.
Solar powered death ray: This image shows how coins can easily be melted with a lens harvested from an old television and used to focus the Sun’s rays
Hot: The beam of concentrated solar power is so strong it can not only boil water in seconds but also burn its way through the glass bottle in which the liquid is contained
Mr Thompson scoured the ‘free’ section of local classified ads to find an old rear-projection television with the right kind of screen to hack out for his project.
Prior to the roll out of large LED and plasma displays, cathode ray tube rear-projection TVs were the first to exceed 40in screen size.
They used three CRTs – one red, one green and one blue – aligned so the colours mix correctly on to a screen incorporating a Fresnel lens – the same type of lens used in lighthouses.
Although they once commanded retail prices of many thousands of pounds, such ageing television sets are now easy to get hold of because they cost more to fix than they can be sold for.
Hack job: Grant Thompson harvested the lens from an old-style rear-projection television set…
… and mounted it in this homemade frame