WRE-420 WRE-421 WRE-341 WRE-342 WRE-343 assembly thermocouple, metal film resistance. The alloy is heated in a vacuum, and the alloy evaporates, so that a conductive metal film is formed on the surface of the porcelain rod. Notching and changing the thickness of the metal film can control the resistance. Compared with carbon film resistors, this type of resistors are small in size, low in noise, and good in stability, but they are more expensive. Metal film resistors have high accuracy, good heat resistance, small temperature coefficient, and small electromotive force. use. Its characteristics: good stability, small temperature coefficient, strong heat and humidity resistance, stable and reliable resistance, better voltage coefficient than carbon film resistors, a large operating frequency range, low noise electromotive force, can be used in high-frequency circuits. Disadvantage: Poor load stability.
Carbon resistance, made by pressing carbon black, resin, clay and other mixtures through heat treatment. The color circle on the resistance indicates its resistance value. This kind of resistor has low cost and wide range of resistance value, but has poor performance and is rarely used.