Can you think of anything good to use as an alternative for an LDR sensor?
By BambiDee
@BambiDee (114)
January 14, 2012 9:38am CST
Attention Tech Geeks! Oooppss... kidding... I need some help.
Me and my classmates are going to make some sort of a prototype machine and we're going to use sensors. We're wondering what's a good alternative for LDR sensors which is of course, like LDRs, we're looking for cheap kinds. Can you think of anything?
1 response
@owlwings (43910)
• Cambridge, England
14 Jan 12
The commonest and cheapest LDR is a Cadmium Sulphide strip (suitably arranged for maximum area) connected to contacts at either end and enclosed in a clear epoxy shell. These are very cheap and are used in many devices. There is really no substitute which can easily be made from readily available materials.
To obtain one for practically nothing, you might look for them in, for example, the kind of external light which is used to welcome visitors (or deter burglars) and turns on at the approach of a heat source. These will ALSO contain an LDR because they are designed not to operate in daylight.
@owlwings (43910)
• Cambridge, England
14 Jan 12
Some diodes and transistors are also light sensitive and are enclosed in light-tight casings for this reason. It is possible to use some of these devices as light sensors (with suitable circuitry). This page may help: http://www.electronics-tutorials.ws/io/io_4.html
@owlwings (43910)
• Cambridge, England
14 Jan 12
You might also try using a solar cell from an old solar-powered calculator. You would need to have a circuit to detect an EMF from the cell when it was illuminated (rather than one which measured resistance across the device).
