Vishay Introduces Trimmer Webinar, Streaming Video Comparison Demonstrations of Bulk Metal Foil Resistors and Trimmers Under Real Environmental Conditions on Website

Resistors and trimmers utilizing different technologies often seem alike on the surface, and may even have similar published specifications, such as initial TCR and tolerance. However, the resistive material and processing methods for each are unique. These inherent resistive material, design, and processing variations strongly influence electrical performance, leading to different behaviors after mounting. For example, the stability of a resistor or trimmer should be judged by its performance under load and temperature in short-term and long-term exposure to different electrical or mechanical parameters.

Vishay's trimmer webinar highlights the differences in trimmer technologies, with a specific focus on high-precision applications. A trimming potentiometer is a mechanically driven variable resistor used to trim resistance in an initial circuit, or to adjust this circuit for drift characteristics after load life, shock, thermal shock, or some other circuit-changing experience.

When used as a variable resistor, a trimmer is called a rheostat. When used as an adjustable voltage device, it is called a potentiometer. These devices can be used in general-purpose, non-critical applications, as well as in precision applications; the end application determines which type of trimmer is most appropriate.

There are four categories of characteristics that are generally considered when selecting a trimmer: mechanical, electrical, operational, and economic. While some of these categories may be interrelated, it is generally the operational characteristics which are of paramount concern, and are also the most elusive in high-precision applications. Consequently, Vishay's webinar concentrates primarily on operational characteristics and, to some extent, the technological factors which affect them.

In addition to the webinar, Vishay offers a new three-minute video which compares the stability of different trimmer technologies when subjected to mechanical shock and vibration. The demonstration shows that while mechanical shock and vibration will cause most trimmers to drift over time, Vishay's Bulk Metal Foil trimmers have a life stability that can rival fixed resistors.

To demonstrate the differences in resistor technologies, Vishay's website offers videos that feature an accelerated life test, demonstrate the in-circuit performance of Vishay Bulk Metal Foil resistors when subjected to ESD, and highlight the Temperature Coefficient of Resistance (TCR) performance of Bulk Metal Foil devices.

TCR is the best-known parameter used to specify a resistor's stability, and is used to depict the resistive element's sensitivity to temperature change due to ambient temperature variations. TCR shows how resistors will behave under cold operating (- 50 °C) and high operating temperatures (+ 150 °C).

Power Coefficient of Resistance (PCR) is a lesser-known but still extremely important parameter, especially for current-sensing applications. This parameter quantifies the resistance change due to self-heating when power is applied. Vishay has introduced a new four-minute video that demonstrates the effect of PCR on different resistor technologies.

This new demonstration provides a directly perceivable explanation of the primary factors that influence resistor stability in a real environment, compared to the specifications on a datasheet, and shows how Bulk Metal Foil resistors offer exceptional reliability and long-term stability compared to other resistor technologies.