i want to build a very basic light sensor, as sort of a substitute for real distance sensing with ultrasonic i want to put my hand above it and have higher (or lower) values if my hands covering it than if its more far away from it, so why not use a simple light sensor first... i'll try out using the data for audio control then, let's see...
i have a photoresistor here (which is quite easy to use, of course) and phototransistors, and i'm using a phototransistor now because the resistor reacts too slow my phototransistors came in a light barrier set, its these ones: http://www.pollin.de/shop/dt/NzA0OTc4OTk-/Bauelemente_Bauteile/Aktive_Bauelemente/Optoelektronik/Infrarot_Lichtschranken_Paare_TEMIC_K153P.html
can i use them for sensing visible light, not infrared light, too? does it make any difference concerning the sensibility?
is this the right way to build the "circuit" up? i don't want to damage anything, so...: (sorry, the labeling arrow should point to the little black box, not to the poti, of course...)
i found two different examples about how to use the phototransistor as a sensor, this one:
I built this circuit:
+5V----Resistor 18kohm----+------PhotoTransistor------GND | | Arduino
(here, the resistor is before phototransistor and analog pin is also before transistor... why is this and whats the difference? is mine better than this?)
...and this one: http://dm.risd.edu/~pbadger/AM/pmwiki/uploads/Main/Phototransistor2.png (here, they used a "reversed biased" transistor... i don't get it. i am not wrong connecting it just like i did, am i?)
- how is the best way to build a sort-of-distance-sensor with a phototransistor? it should be influenced by holding a hand above it and coming closer or going more far away... maybe with infrared LEDs and reflection? or what do you think?