Quoted from bobukcat:Well LEDs CAN dim for certain but strictly for the purposes of the discussion specfic to WPC pinball machines - they don't without flickering unless you use a 3rd party board. If the OCD boards are not readily available I did read a comment in some other thread recently that there are similar products available that are made in the EU somewhere but I don't remember the name of it.
Ghosting is completely different and happens to controlled lamps, not GI. I don't remember the technical reasons too clearly but sufficit to say that it is caused by the matrixed / pulsed circuit design. These can usually be eliminated by using non-ghosting LEDs if you don't want the expense of an OCD or OCD like board and can live with the rapid on/off timing of an LED versus the smoothed ramp up/down you can get from the OCD type board. Some people's eyes are bothered by the flickering and others seem to be immune to it.
My understanding of ghosting is that there is a very small amount of voltage at an insert if for example another one downstream is on.
For a bulb, this is not enough voltage to turn it on. For an LED, it is barely enough to turn it on very dimly.
A non ghosting LED has a higher threshold for turning on, so it just ignores low amounts of voltage.