The early days

Alan’s interest in the weather stems from his days as an airline pilot. In 2009 he bought a small weather station and started recording the weather data. He soon realised that there was one element that was missing and that was sunshine duration.

‘I forget now quite how it happened’, he said, ‘ but I noticed one day that a point source of light reflected off a lamp bulb and could be seen wherever it was viewed from’.

He realised that the converse would be true – that a fixed viewing point would see the light source wherever that source was.

From that idea the first prototype sun recorder was born. Using a photosensitive resistor driving a relay and a spherical light bulb he had the makings of sunrecorder one.

The idea worked with the relay driving a small battery clock but not as well as Alan hoped. The sensitivity of the relay circuit had to be adjusted fairly frequently and it seemed that the spot of reflected sunlight was too small in comparison to the general lighting of the whole bulb.

Maybe a bigger bulb would work better so this led to sunrecorder two.







Sunrecorder two worked better and was linked to a computer through a game port. Sensitivity, though, was still something of a problem.

Alan had been publishing his ideas on the Sandaysoft weather forum and it was generating a great deal of interest.

It was through the forum that Ole Larsen saw the potential of the system. Ole had the electronics and programming skills that Alan needed to progress the idea.



Ole and Alan made contact and exchanged hundreds of emails with many ideas for the perfect sun recorder – some very different from the original. In the end the spherical reflector seemed to be the simplest and most effective answer. It was when Ole invented an algorithm to establish a sun ‘ON’ threshold that the ‘Two old men in their sheds’ – as someone described them – had a really workable alternative to the Campbell Stokes and other recording methods. The recorder in its present form should be affordable by the amateur weather enthusiast and judging by the number of hits on the weather forum – now standing at over 14000 – it is something that will fill a gap in the weather recording data set.