Hans Kerensky

Hans Kerensky

Posted on 07/06/2013

Photo taken on July  6, 2013

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Light Sensor Experiments (01)

Light Sensor Experiments (01)
Light Sensor Experiments.

So having a BPW21 photodiode lying around for quite a while i decided it was time for some experiments to get to know it a bit better.

The BPW21 is choosen because it was specificly designed to be sensitive for light in the human visible spectrum. As most films for our classic cameras are designed for that same spectrum this seems to be a good choice.

A quick search gave a nice article from Dr.Taiga (a pseudonym) about a set-up with an Op-Amp (operational amplifier) and a photodiode. You can find that here : Doctor Taiga Article
So i bought the components, breadboard and some jumpers for an experimental set-up.

Power supply in my case is a accupack from 4 NimH cells which also gives about 5 Volts like in Dr.Taiga's article.

Because the Op-Amp is set up as a regular amplifier there is a nice analog value coming from it's output which should be more or less linear with the amount of light picked up by the Photodiode.

In this set-up, exposed by 2 daylight lamps from the side, the output is a nice 0,195 Volt.

So, with a Photodiode set-up like this it should be possible to get indications about both shutterspeed as well as light strength.