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Orion said:
I did read it, but I don't have much electronics sense to fully understand it, nor to create what you suggested in that thread. I have a multi meter, but the only thing I use if for is checking voltage of batteries. I've never really understood how to do other things with it. I guess I have had a lack of interest/time to study it more.
Anyway, at 72 hours, the light output is still the same, as perceived by me, and when compared to my Arc AAA. I'll keep you all informed.
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Cool. Please bear with me:
The idea itself is simple. You take a part that changes with light level and use that change to measure the light level. The device I'm promoting (this means giving away) is very small, smaller than a small LED, the more light that falls on it's face, the more it will conduct. Your DMM measures conduction, using the Ohms ranges, it will give you a digital number representing conduction of whatever you put between the leads. This means if you put the two leads of the detector between the leads (one lead to each) and have the meter on the proper range it sill show conduction and therefore the light level. A number representing the light level.
There are problems with this sort of system in measuring the exact level (say in Foot Candles). First off the numbers go 'backwards', more light is lower numbers. And twice the light isn't half the number (or any logical one, only smaller). However, it is repeatable, that is it will give you the same number each time for that level of light.
So what we need to do it figure out what that number will be and watch for it. In practice, this means putting the sensor 'looking at the light' a foot or so away, turning the light on and *inserting a filter that removes half the light*. Note the reading, remove the filter (reading number goes down due to more light) and wait. When the level returns to the 'target' level (half the initial light output) the same level of light will reach the detector as when the filter was in place with a 'full blast' light at the start (when you did the calibration and noted the target meter value), the meter will show the same number again, and the test is over. You can even watch the number slowly climb up to the target as the battery runs down.
No need to study the theory, all you need to know is how it works, and now you do. FWIW, I think you (obviously) have enough interest in this stuff, and I don't think it's at all too difficult for you.
BTW, I did some checks on the Arc AAA I carry. It looks like half the light at 1.5 Volts in, comes at a bit over .95 Volts. Sometime I'll have to look further into this, it looks like the Arc is less efficient (light out for power in) at normal levels????
Anyway, think it over. I think you can be checking against a real repeatable threshold (half light output) very easily. Puts real value in the data.
Doug Owen