WRR-330 WRR-321 WRR-322 WRR-323 WRR-331 B thermocouples
WRR-330 WRR-321 WRR-322 WRR-323 WRR-331 B thermocouples, the current source needs a sampling current for feedback. Although there are other methods for sampling, the most stable and accurate method is still resistance sampling.
Popular knowledge: The resistance power used for sampling is at least 20 times greater than the sampling power, so that no obvious drift due to heat is caused.
Continuing last time, the current of 100mA_ level is a very common current value, but it is usually an awkward current value for resistance sampling.
A_ grade current does not usually require too high accuracy. It is mainly sampled with a shunt, as long as the power is sufficient.
The mA / 10mA_ level current is relatively simple. Since it does not produce significant sampling power, the usual precision metal film resistors can meet the requirements.
The current of 100mA_ is not small or small. It does not have such a large resistance value with a shunt, and it does not have such high power with a precision metal film resistor.