Q. Automatic Adjustment Potentiometers.
Q. Can the rotor and adjustment shaft be thread-locked after adjustment?
Q. Does the product have polarity?
Q. Can I coat the product with a moisture-proofing agent, or the like?
Q. What are the differences between a Carbon resistive element and a Cermet resistive element?
The main types of automatic adjustment potentiometers are as follows.
(1) PVZ2 Series, (2) PVZ3A Series, (3) PVG3 Series
By installing a mechanism that has an image sensor to detect the position of the position of the adjustment screw, automatic adjustment can be performed on all of products. However, the automatic adjustment potentiometer what Murata refers to is a component which has a function for mechanically guiding the adjustment screwdriver itself.
For this purpose, the following are employed in the potentiometer.
(1) Cross-shaped driver slot, (2) bowl-shaped rotor, (3) enlarged rotor area
The only products which can be thread-locked are hermetically sealed products whose wiper and resistive element are not exposed.
Use thread-locking adhesive which does not contain substances that can corrode metals, such as chlorine and sulfur. When using thread-locking adhesive, carefully evaluate its performance on an actual potentiometer.
Products which use a Cermet resistive element do not have polarity.
When applying DC to a product which uses a carbon resistive element, ensure that the wiper side (No.2 terminal) is the anode (+) , in order to prevent anodic oxidation.
Depending upon the cleaning liquid and condition that you use, it is possible to wash the product. However, if you wash the product to an excessive degree, you risk losing the function of the trimmer potentiometer. Before using cleaning liquid, carefully evaluate it on an actual product. When making inquiries concerning whether or not a product can be washed, please submit details of the cleaning condition, and then consult with us.
As with thread locking adhesive, you can apply a moisture-proofing agent only to a hermetically sealed product.
Likewise, use a moisture-proofing agent which does not contain substances that are likely to corrode metals, such as chlorine and sulfur.
When using a moisture-proofing agent, carefully evaluate its performance on an actual potentiometer.
A carbon resistive element is made using carbon as the conductive component, and resin as the binder. It is inexpensive, but because it uses resin as the binder, variations of the resistance value due to heat and humidity are kind of big.
A cermet resistive element is made using ruthenium oxide-based metallic particles as the conductive component, and glass as the binder. It is expensive, but because it uses a glass binder, variations of the resistance value due to heat and humidity are small.
If you turn the knob only a few revolutions, there will be no particular problem concerning the product quality.
However, please note that neither the electrode nor the resistive element exists past the maximum electrically effective rotation angle, so the No.2 terminal will be open circuit.
We have available recommended screwdrivers for all series. The part No. of these screwdrivers are listed in "Precautions for adjustment (Handling) " in the detailed information. You can purchase these recommended screwdrivers from us by indicating the Murata part No.
Please note the kind of screwdriver, insertion angle and the load.
For more details, please refere to the attached video.
