Posted on 25 December, 2016 by Mathew
I bought some LED string lights before Christmas and we had them in the office, for some random cheer. The lights were mixed colours, red green and blue. They were powered by two AA batteries, and we left them on continuously for more than a week. After a while I thought some of the lights were broken but later someone else pointed out to me that only one colour remained lit.
Only green LEDs for Christmas?
With only the green LEDs apparently lit, the voltage measurement on the battery was 1.153 V (1.156 V with no current flowing). A fresh battery capable of lighting all the colours of LED provides a voltage of 1.311 V with the current flowing (1.325 V with no current flowing).
LEDS lit R-G-B with full voltage.
Strangely green LED’s are the least efficient colour, so it’s strange they would be the last ones lit…
For change in voltage, red LEDs take the least to work, and as the colour moves up the colour spectrum toward blue, the voltage requirement increases (green is between red and blue).
Approximation of spectral colours on a display results in somewhat distorted chromaticity — Wikipedia
So does this mean these LED’s aren’t really naturally green ones, and rely on phosphor filtering? Or some other technology?
Is this a problem of perception of brightness of different colours?
Filed under: Cambridge, Electronics | Tagged: Science Questions, Science. Christmas, String Lights, Tree Lights | 3 Comments »
Posted on 14 August, 2016 by Mathew
Digital electronics engineer James Newman, has built a ten meter long, two meter tall processor using transistors. Running at speeds up to 8 kHz the project ran out of control with total spend of forty thousand UK pounds (£40k). Unlike a computer on a chip, the system allows visualisation of the processes and architecture of a modern computer central processing unit (CPU). James is looking to site the computer in a museum or have it tour the UK to educate the public. Currently it’s possible to visit the computer during open days in James’ lounge were the machine was built.
A physically large chunk of memory built using LEDs allows visualisation of the data stored, and can be used to play Tetris!
Take the tour:
More info on the Magaprocessor website: http://www.megaprocessor.com/.
Other homebew machines can be seen here: Home Brew Computer Ring.
Filed under: Cambridge, Cambridge News, Computers | Leave a comment »
Posted on 19 January, 2015 by Mathew
BBC radio Cambridgeshire held a debate with five candidates who have declared they will be standing for the member of parliament for Cambridge.
Julian Huppert – Liberal Democrats
Patrick O’Flynn – UKIP
Rupert Read – Green Party
Chamali Fernando – Conservatives
Daniel Zeichner – Labour
Filed under: BBC, Cambridge | Leave a comment »
Posted on 2 May, 2012 by Mathew
`Cam conservators’ have introduced their final solution to permanently resolve the Mr Asbo problem and removed him to an `undisclosed location’.
Filed under: Cambridge, Cambridge News | Tagged: Cambridge, Swan | 1 Comment »
Posted on 20 October, 2011 by Mathew
Lord Sainsbury of Turville has been elected by Alumni (the Senate) of the University of Cambridge. Lord Sainsburys succeeds the Duke of Edinburgh who retired as Chancellor on 30 June 2011.
The election was the first election since 1950 and the first to use the single transferable vote system. Lord Sainsburys received 52% of the vote on the first count.
Number of valid votes cast: 5558 Quota 2779
|Mr Abdul Arain
|Mr Brian Blessed
|Michael Mansfield QC
|Lord Sainsbury of Turville
I’m not sure how we survived since 30th of June without a Chancellor?
Filed under: Cambridge, Politics | Leave a comment »