Resistors
- HIGH ACCURACY
- LOW TEMPERATURE COEFFICIENTS
- HIGH IMMUNITY FROM ENVIRONMENTAL EFFECTS
- HIGH RELIABILITY - FROM 0.01 Ω TO 10 MΩ
- BY SPECIAL ORDER ONLY
- PRECISION HIGH POWER RESISTORS AVAILABLE
Ohm-Labs' can supply critical resistor components to customers who require the highest quality and reliability.
Our acquisition of Leeds & Northrup's, Honeywell's and Julie Research Labs' resistor manufacturing materials and wire allows us to continue to offer wire wound resistors using these designs and materials.
Ohm-Labs can supply and support all of L&N, Honeywell and Julie Research Labs resistor products. Please provide us with their OEM part number for a quotation.
To specify precision resistors, please refer to the chart below.
- First, select the type: either 'R' (epoxy encapsulated), 'H' (hermetically sealed and oil filled), or 'T' (top hat, or radial lead).
- Then, select the desired size (diameter and length) - recommended sizes for small resistors are R24 & R32, for larger resistors R44, R46 or R48 (or H type).
- Specify 2-wire or 4- wire construction (4-wire is recommended below 10 ohms).
- Specify your desired accuracy and TCR (Temperature Coefficient of Resistance).
- Finally, specify the resistance.
- Smaller resistors <34 size are typically 1/2 W; 44 and larger size are typically 1 W.
- For higher power, specify -HK heat sink type.
Precision Resistor Part Number Guide - Type and Size Selection
| Type | Diameter in 1/8ths | Length in ¼'s |
Leads |
| R = Epoxy | 2/8 = ¼" | 2/4 = ½" | 2- Wire |
| H = Oil Filled Herm. Sealed | 3/8" |
3/4" 4/4 = 1" |
2- Wire 4 - Wire |
| T = Top Hat (Radial) | 4/4 = 1" 6/4 = 1.5" 8/4 = 2" |
||
| Tolerance and Resistance Selection | |||
| Accuracy* | TCR ppm/°C |
Resistance | |
| A = 0.1% | Specify resistance | ||
| B = 0.05% | A = <20 | ||
| C = 0.025% | B = <10 | ||
| D = 0.01% | C = <5 | ||
| E = 0.005% | D = <3 | ||
| F = 0.0025% | E = <1 | ||
| G = 0.001% | |||
*Stated accuracy is at time of manufacture. 12-month stability is typically <20 ppm
Examples
- R462DC-1M = Epoxy ½" x 1.5" 2-wire 0.01% 5 ppm TCR 1 Meg
- H484AD-1 = Oil filled ½" x 2" 4-wire 0.1% 3 ppm TCR 1 Ohm
- T422BB-25.5 = Radial ½" x ½" 2-wire 0.05% 10 ppm TCR 25.5
Precision Power Resistors - HK Heat Sink Type
- H484DC-[ohms]-HK are heat sink mounted precision power resistors
- Common values range from 0.1 to 100 ohms
Please note that due to wire size restrictions, not all resistance values are available in all sizes.
Ohm-Labs can manufacture custom-matched resistor sets for precision ratio applications.
On a special-order basis, Ohm-Labs can manufacture Leeds & Northrup and Julie Research Labs type wire wound resistors, including ratio sets and OEM replacement parts. Please contact us for more information.
