Design Problem: Electronic board game

crutschow said:

A capacitor will have no effect on DC sensitivity. Capacitors affect AC signals, not DC.

A transimpedance converter is useful for low level analog signals. It's not needed here.

Click to expand...

While we're at it, the one I ordered is: LM324N (datasheet).
I saw some other projects such as this youtube video where they use this amplifier together with photo diodes.
Of course if I can do without this part, that would be a nice way to safe some budget.

crutschow said:

As I stated in my previous post, photo-transistors are more sensitive and would likely work better in your application. Some photo-transistors have three leads, with one lead connected to the transistor base for adjustment of the sensor's gain and speed. You probably can just leave the base open. You can experiment with the resistor value in series with the collector to determine what value gives the desired signal voltage change.

Click to expand...

Hmm, you actually revealed something to me here ... so 2 lead photo transistor isn't the same as a photo diode?
Some ebay sellers seem to use the words through eachother.
I currently use RPT-311PTA49, which seem to be 2 lead photo transistors after all, and not photo diodes. (The voltage values which I mentioned in my previous post are for this photo transistor)

At first I didn't want to use 3 lead photo transistors because they are more expensive.
But now I have ordered 3 lead photo transistors after all: MID-95A3L (**broken link removed**)

The thing I'm worried about with this one is that the datasheet shows an internal construction of 2 parrallel transistors. Is this usual for 3 lead photo transistors?