New techniques improve wirewound performance

An Ohmite product story

Edited by the Electronicstalk editorial team May 30, 2007

Wirewound resistors offer tolerances down to 0.001% in both axial and leaded versions.

By using newly acquired manufacturing techniques whereby components are wound on plastic bobbins, rather than on ceramic cores, by pile winding with insulated wire, which is commonly used to attain very high resistance values, Ohmite's new range of Ultronix wirewound resistors, offer tolerances down to 0.001%.

Special versions involve the use of very high TCR wire, so the resistors predictably change value as temperature rises; a characteristic sought after in some applications.

Offering minimum values of 0.1ohm for +/-1 and +/-0.5%; 10ohm for +/-0.1% and tighter and resistance tolerance of +/-0.005, +/-0.01, +/-0.02, +/-0.05, +/-0.1, +/-0.5 and +/-1%, depending on style and value, the resistors have a temperature coefficient (TCR) of +/-10ppm/C standard for 10ohm and above.

High TCs up to +6000ppm/C are available.

The operating temperature range is - 60 to +145C.

Ohmite has released two ranges under the Ultronix name.

HPW Series high precision welded resistors are available in both axial and leaded versions, and the HSP Series is an axial leaded hermetically sealed precision ultra-high-stability device.

Other features of the Ultronix range include extremely low thermal EMF and low noise.

Applications for this type of resistor include fuel monitoring, especially in the aircraft industry.