Using newly acquired manufacturing techniques, Ohmite’s new range of Ultronix wirewound resistors offer tolerances down to 0.001%. The technique involves winding components on plastic bobbins, rather than on ceramic cores, by ‘pile winding’ with insulated wire, which is commonly used to attain very high resistance values.

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 0.1 Ohm for ±1% and ±0.5%; 10 Ohm 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/degC standard for 10 Ohm and above. High TCs up to +6000ppm/degC are available. The operating temperature range is -60 to 145degC.