1. Field of the Invention
The invention relates to a variable resistor, and more particularly to a rotary variable resistor that includes three input circuits and a resistance ring.
2. Description of the Prior Art
Generally, applications of variable resistors to control electronic devices can be seen everywhere in daily life. For example, the variable resistor can be used to control volume of audio equipment. Theoretically, the variable resistor is a resistor having two opposing end terminals to be fixed at two predetermined points and a middle contact to slide between these two opposing end terminals. With the middle contact to change its position on the transistor, corresponding voltage divisions could occur at this variable resistor.
As described, conventional variable resistors can be structurally classified into two groups: sliding variable resistors and rotary variable resistors. In particular, the rotary variable resistors can be further classified into single-turn variable resistors and multi-turn variable resistors. The single-turn variable resistor is a C-shape resistor having two close end terminals and a middle contact to slide along the C-shape resistor for generating different voltage divisions. On the other hand, the multi-turn variable resistor is consisted of multiple C-shape resistors for generating various voltage divisions. In the art, though the multi-turn variable resistor can generate more voltage divisions than the single-turn variable resistor, yet the structuring of the multi-turn variable resistor complicates the manufacturing process, and thus the cost thereof is hard to be lowered anyhow. Nevertheless, no matter what the single-turn variable resistor or the multi-turn variable resistor is, the rotational angle of the resistor is limited to the structure of the C-shape resistor.