Light Meter. How to Make an Proper Readout?

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MCU88

Joined Mar 12, 2015
358
Hello...

I have made an project that has an LDR and ten LEDs that respond accordingly to the level of light that the LDR sees. Q: How do I add some numbers, a scale to the LEDs so that they have an meaningful readout?




 

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DickCappels

Joined Aug 21, 2008
10,152
If you want to make something calibrated and that works with different light sources you would need a filter or set of filters to correct the response of the LDR to have a photopic response. This is approximately the same response as the "green" receptors in our eyes. An expensive solution.


https://en.wikipedia.org/wiki/Photopic_vision

If you consistently use it with the same kind or light (for example, same color temperature florescent or incandescent) then you can simply place a diffuser over the LDR (a ping pong ball cut in half works nicely) and then put it on the desk side-by-side with a borrowed illuminance meter (sometimes called a "Lux meter"), which is calibrated in Lux (for the originator of the until, Harrold Luxemberg) and calibrate your instrument for different amounts of incident light.
 
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