Trimmer Potentiometers are semifixed potentiometers that it's resistance can be changed freely. They are used in some applications that usually almost have no need to adjust again after first time adjustment. So to avoid be touched easily, they are set inside of products. On the other hand, rotary position sensors are also called variable resistor, but they are the parts that adjusted by turning the knob outside of products.
There is a table about the classification of trimmer potentiometers.
In general classification, there are sealed type products with high regard for environment resistance and open type with high regard for cost. And there is also another way for distinguishing, multi-turn products with high resolution and single - turn products with high cost performance.
| Structure/ Adjudtment turns |
Sealed type | Open type |
|---|---|---|
| Single - turn |  |
 |
| Multi - turn ( ) number of rotation |
 |
To adjust the reference voltage (VCOM) of LCD.
With inappropriate reference voltage, there will be flicker on LCD screen.
Use trimmer Potentiometers to adjust reference voltage for flicker restraining.
LCD has some flickers if the voltage is not suitable for LCD.
You can reduce the flickers when you adjust the voltage by using trimmer potentiometer.
As record media Blu-ray, DVD and CD etc. usually be used, and we use optical pick - up for the data reading and writing from disc. In an optical pick - up, there is a light - sensitive element to detect reflected light from disc.
And a trimmer potentiometer is used to adjust the sensitivity of this light - sensitive element.
Circuit example Playback system device (ex, DVD, CD, playback)
There are all kinds of sensors around our life.
For these sensors, trimmer Potentiometers are used for suitable sensitivity.
A fixed resistor with a mechanism to change resistance construct a trimmer potentiometers. The principle is with the changing of resistive element length according a wiper sliding, the resistance will be changed. Use this method, with same sectional area, the resistance can be changed relative to resistive element length, and products can be manufactured in low cost.
| R: | Resistance [Ω] |
|---|---|
| ρ: | Resistivity [Ω/m] |
| L: | Resistive element length [m] |
| S: | Resistive element sectional area [m2] |
There is the relationship between wiper position (angle) and resistance in below figure.
*The output wave is besed on below conditions.
Resistive element is round shape (U - shaped) /Single - turn/No whirl - stop.
Construction
Single - turn, no whirl - stop type
The relationship between wiper position (angle) and resistance
By using trimmer potentiometers, it is no problem to set surrounding circuit constant roughly.
Would you please use trimmer potentiometers if it is difficult to decided on a resistance value in your circuit. You can design your circuit roughly and quickly as the result.
