I have two phototransistors. If I measure the impedance (what I understand to be essentially the resistance of anything that's not a resistor) across just one of the phototransistors, then I measure around 235K. I've checked that they both measure the same.
But if I then put the phototransistors in parallel, then I measure 36k.
My understanding is that if I have two of the same impedances in parallel then they should measure as half the impedance, which should be around 112K not 36K.
The light conditions are not changing in the room. I am measuring with the red lead on the flat side (emitter) and the black on the collector. Can this really be happening?