Temp. regulator for thermal cutters - has metal-film resistor which is used as temp. sensor and which is coupled to trigger operating thyristor switch

摘要

The temperature regulator, for thermal cutters, has a variable resistor as temp., sensor and a thyristor as load switch in the heating element's supply circuit. A threshold trigger (2) is connected between the temp., sensing metal-film resistor (11) and the thyristor (42). This trigger may be a Schmitt trigger (21, 22) whose threshold is adjusted by a potentiometer (12). The metal-film resistor has a temp., coe., greater than 3,500 ppM. Alternatively the trigger can also be an operational amplifier with the film resistor at its non-inverting input a and the threshold-setting potentiometer at its inverting input.