Taps

The location of the tap may be specified by:

• The mechanical angle
• The effective electrical angle
• Voltage output
• Resistance value

Wirewound Taps

On wirewound elements, single wire terminations (tap weld) are typically used for intermediate connections (taps) in order to minimize the width of element shorted by the tap, and to provide more accurate placement of the tap. However, it is inherent to wirewound construction that the effect of a tap cannot be limited to a single turn of wire as illustrated in Figure 11.14.

Figure 11.14

Non-Wirewound Taps

On non-wirewound elements, there are two methods of providing taps: voltage tap or current tap.

Voltage tap - is a connection made on the edge of the element. It provides a minimum contact with the element in order to minimize distortion of the current path through the element and to insure that the tap introduces little or no distortion in the output of the potentiometer. A voltage tap can only be used to provide a voltage reference. Current drawn through a voltage tap will distort the potentiometer output and may destroy the tap connection.

Current tap - utilizes a narrow band of conductive material deposited across the full width of the substrate, shorting out the section of the element in a manner similar to SILVERWELD® in wirewound elements. This creates a step in the linearity curve, but will not distort the output while drawing current from the tap.

Unspecified taps are assumed to be voltage taps. If the customer requires a current tap, it must be specified. Figure 11.15 illustrates the two types of taps and the related output.

Figure 11.15

Tap Terminal Position

Tap terminals are placed on the potentiometer housing as closely as possible to the element's tap. However, an alternate location may be specified. Virtually any number of taps may be utilized, within the limits of space available for terminals on the potentiometer case.