The BS407 is an instrument which is fully optimised for the task of accurate measurement of low resistances with a best resolution of 1µOhm.
Most multimeters offer a best resolution which is at least one thousand poorer than this. A very high resolution multimeter may attempt to resolve fairly low resistances, but it does so by resolving extremely low voltages (typically one nano-volt per micro-ohm), making it subject to severe errors from thermal emf effects and noise.
In contrast, the BS407 generates sufficient test voltage across the unknown resistance to combat noise and reduce thermal emf effects to manageable levels. Current reversal can then be used to eliminate any remaining thermal offset.
|High basic accuracy of 0.1%|
|Wide range of 1µ Ohm to 20k Ohm|
|Current reversal switch for detecting thermal emf effects|
|Current diversion switch for easy zero-ing|
|Four terminal measurement using Kelvin clip leads|
|Battery operation with built-in charger|
|20mV clamp for ‘dry circuit’ testing|