I'm trying build a frequency meter to measure the frequency of displays.
So I need to measure frequencies up to 120Hz, no more.
I tried using a phototransistor ( http://www.tranzistoare.ro/datas... )
but sensitivity is too low to detect something...
Is there a design that can increase sensitivity ?
Can a photodiode be more sensitive than a phototransistor ?
I also tried to find a sensor with a peak more in the visual range, but all I found had peaks around infrared.
I also guess bigger sensors will be more sensitive...
But I need to find one...
Thanks again for you help.
I tried the following design :