User:DavidB4/workspace

The following is personal workspace. Once content is ready, I will migrate it to the appropriate location. I may use this for any number of purposes, but generally it will be used for drafts.
Please to not change the value of this content. If you see a typo or some other small problem, feel free to change this. For anything else, please ask first. Thanks!

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A dimmer switch is a device which allows for the adjustment of power supplied to one or more electric lights. In some rare cases, they are also used for other electric devices, but in many cases doing so would harm the device, so this is rare.

Types

Rheostat (variable resistor)

The first kind of dimmer switch made use of a variable resistor. In this kind of device, a semiconductor strip is placed between two contact arms--one is stationary, one is adjustable. The semiconductor permits the flow of electricity, but does resit it somewhat. The stationary contact arm is placed at one end of the semiconductive strip, and the adjustable one is permitted to move across it. When the latter arm is placed right near the stationary arm, electricity flows from one arm through a small amount of the semiconductor, and out to the other arm. Since it only passes through a small amount of semiconductor, the power flow is minimally effected. However, when the adjustable arm is moved down the strip, away from the stationary arm, the amount of semiconductor the power must flow through increases. This prevents progressively more electricity from passing through, as the arms separate.
This simple system is then installed in a switch, where the user can easily move the adjustable arm. The resulting supply is then connected to some device, usually a light bulb. If the operator wished for a higher power supply, they can simply slide or twist the dimmer control to decrease the amount of semiconductor the energy must pass through. If the operator wishes to reduce the electrical supply, the amount of used semiconductor can be increased, by sliding or twisting the control in the opposite direction.
Unfortunately, while this setup does allow for easy adjustment of the electrical supply, it is inefficient. Much of the energy which would have gone through the controller is instead converted to heat. This causes the output voltage drop desired, but most of the electricity is still being used, as it is converted into heat energy. In some cases, this can also be a safety hazard since the heat can build up and potentially cause fire or other damage.

Switching circuit

Rather than resisting the flow of electricity, switching circuit dimmers simply cycle the power on and off. They work on alternating current be shutting of the flow every time the sine wave cycles to zero, then connecting it again a split second later. AC current completes sixty cycles per second, and in every cycle the sine wave comes to zero twice. This means that 120 times every second, the first part of each positive and negative sine wave is "chopped" off. The amount of the wave which is cut off can be adjusted, so that more or less of each wave can pass through.
As portions of the waves are cut off, the net power allowed through is reduced. Although this does cause the output to be inconstant, most people will not notice since it is so quick, the the human eye, nerves, and brain can only process visual input at a limited speed. (This speed is not knows precisely, though some approximate that about 60 frames per second (FPS) can be processed, and others simply say that the processing rate is over 43 FPS.) However, some do actually notice this effect, and usually report that it is irritating. Others report that light emissions which have been "dimmed" in the manner seem harsh, but cannot identify why. (For this reason, some dislike the LED Christmas lights, and certain other such products.)

Autotransformer dimmer

(Variac)

Solid-state

(aka semiconductor)

Field effect transistor

[1]

CFL/LED dimmers

[2][3]

[4] [5] [6] [7]