Various Variable resistor or varistor Article
Variable resistor (variable resistor or varistor) is a resistor whose resistance value can be changed or can be changed. There are various variable resistor include:
1. Potentiometer (Potentiometer)
Is a three-terminal resistor whose resistance value can be changed by shifting (for potensio type shear) or play (for potensio rotary type) lever, use the lever meant that the circuit is often done using a potentiometer settings, and is intended for the user, on the television set example the part that is often done is part control audio settings, brightness, contrast, and color.
Potentiometer type there are two kinds of linear (lin) and logarithmic (log). For this kind of linear scale shift lever (for the sliding model) or the angles playback lever (for the rotary model) proportional or directly proportional to the change tahananya. While this type of logarithmic scale shift lever (for the sliding model) or the angles playback lever (for the rotary model) is not proportional but according to the logarithmic function graph (logarithmic law suits) against changes tahananya, logarithmic potentiometer can be made of a linear potentiometer coupled with external resistor, because the potentiometer which is really very expensive relative logarithmic, logarithmic potentiometer commonly used in audio volume control.
2. Trimpot (Trimmer Potentiometer)
It is a way of changing the potentiometer resistance values by using a screwdriver mentrim trim. On television, trimpot is usually used to regulate the amount of current the oscillator circuit, driver circuit, or by setting the white balance (white balance). parts using trimpot means the adjustment is not often done and usually only for maintenance.
3. PTC (Positive Temperature Coefisien)
Including PTC thermistor type, resistance value of the resistor is affected by temperature. PTC resistance value is very low when cold, but when temperatures rise, the value of resistance PTC also rose. In the television PTC is usually used to provide voltage to the coil degausing suply (degausing coil)
4. NTC (Negative Temperature Coefisien)
NTC thermistor also includes types, namely resistors resistance value is affected by temperature, but the NTC opposite of PTC, NTC resistance value which is very high when cold, but when the NTC temperature increases, the resistance value will become smaller even zero. In the television NTC is usually installed at the input power, is intended to reduce the shock voltage power supply circuit, so that the effects of the addition of NTC is a condition referred to as "soft start".
5. LDR (Light Dependent Resistor)
LDR is a light-sensitive resistor or referred to fotoresistor, in which the resistance value will decrease if there are additional light intensity about it.
Fotoresistor made from high beresistansi semiconductors. If the light is about him having a high enough frequency, photons absorbed by the semiconductor will cause the electrons have enough energy to jump into the conduction band. The resulting free electron (and its hole partner) will conduct electricity, thereby lowering resistance.
