I'm trying to explain some LED-lighting phenomena, that we (me and my family) have observed, while changing light bulbs into LEDs. I've had some courses in semiconductor physics, and I've had a basic course in electronics, but I still have some difficulties in explaining these phenomena.
In our living room, there are 4 light sources, each of which consists of 4 light bulbs. I assume all of those (16 in total) light bulbs are in parallel, because when one of them is broken, all the others (15 bulbs), still shine. We can turn those light bulbs on with a slider. So it is possible to let them shine on f.i. half the intensity.
We now tried to replace those bulbs with LEDs. The first thing we noticed (when replacing one bulb), is that the LEDs intensity can't be gradually changed by the slider. The LED is shining on full intensity or isn't shining at all. Furthermore there were no problems in changing 15 of those bulbs into LEDs, but when we changed the 16th bulb, for some reason all LEDs start to flicker. Furthermore if we just remove the last LED, there is no light at all. Finally if we replace the last LED again by the light bulb, we noticed that all LEDs are now shining (at full intensity), while the light bulb (which isn't broken) does only glow (and refuses to shine).
I hope someone can help us to explain these phenomena:
1) The intensity of the LEDs can't be gradually changed by the slider.
2) When changing all light bulbs into LEDs, all LEDs start to flicker. Nevertheless they work fine when changing only 15 or less bulbs.
3) When just removing the 16th bulb, there is no light at all.
4) When replacing last LED by a bulb, all LEDs are shining, while the bulb doesn't.
I have some guesses at how this results could be explained (for instance I think the LEDs flicker, because the offset voltage dropped to lower voltages, the LED will then get only in some part of the voltage period enough current to shine). But I have problems in seeing the bigger picture. I think my main problem is that I can't guess the electric circuit, which is the main reason I post this question here. Any attempt to solve these questions will be greatly appreciated!