The title 😀
I would understand it for LED strips and so on, but if both bulbs are made for 230V (or whatever in US), why do they need different dimmers? Is there a difference in some dim range or something?
Thanks.
In: 14
To add to some of the existing comments on here-
A LED and a normal bulb are inherently different.
To supply some background- LED stands for light emitting diode. Diodes are constructed by creating a PN (positive/negative) junction, with a depletion layer in the middle. This means that one material (called P-type) has an abundance of positive charge carriers (holes) and one material (N-type) has an abundance of electrons. The depletion layer can be considered neutral territory. When voltage is applied, the ‘holes’ are pulled across the depletion layer.
It is only when a sufficient number of holes are pulled that we consider the gap “bridged” to complete the circuit and, in the case of an LED, turn on the light (this is called the “band gap”). If this voltage is not met, the circuit is not completed and the light is off- there is no dimming effect. If it is, we can think of the diode as a regular old wire (for this application).
An incandescent bulb does not operate on this idea of bridging a gap to complete a circuit. The gap is always bridged, through a very small bit of wire. As electricity flows through this tiny wire, it creates heat. Enough heat will make light- similar to how a wook poker glows when you leave it in the coals too long.
By increasing the amount of current, an incandescent bulb will glow brighter, but an LED will stay approximately the same brightness. By decreasing the amount of current an incandescent bulb will become dimmer, while an LED will stay the same or turn off.
So we know to change the brightness of an incandescent bulb, we adjust the flow of current (usually done by increasing resistance in the dimmer switch). For an LED, we know that the voltage doesn’t really matter as long as we exceed the band gap voltage. Once that is met, the current flows like a regular wire. So to dim it, as others have mentioned, the light is turned on and off very fast. Faster than the human eye can see. Our eyes effectively take an ‘average’ of what it sees, so this rapid on/off of the light appears dimmer!
This rapid on/off is called pulse width modulation, or PWM for short. By this, people are talking about changing the percentage of time the LED is on (a pulse of voltage).
Because PWM is a bit more complicated than adjusting current, a different dimmer switch is required.
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