Weller w101 100w temperature controlled mains soldering iron weller t0056104399n the weller w 101 is a 230v ac mains voltage temperature controlled soldering iron with an output of 100w making it suitable for medium and heavy electrical connections to transistors pcbs heavy duty connectors and sheet metalthe temperature of the iron is controlled by a built in magnastat thermostatic switch as magnets are heated their strength reduces and this principle is used to operate a spring loa