Central heating and air conditioning electronic temperature regulator - uses pulses generator which periodically supplies wheatstone bridge including thermistor sensor

摘要

The electronic temp. regulator is in the form of a Wheatstone bridge. In one branch of the bridge is a thermistor. This thermistor measures the temp. to be regulated. In another branch of the bridge is an adjustable resistance used to set the required temp. In the diagonal of the bridge is a detector used to selectively drive control stages of a regulating element. The temp. regulator has a pulse generator which periodically sends, during a predetermined period a supply to the bridge. The detector has two transistors. The bases of these transistors are respectively connected to the ends of the bridge diagonals. The collector-emitter circuits are inserted in shunt between the negative pole of the source and two control lines. Each of these control lines connects the positive pole of the source to an amplification stage. This amplification stage is connected to a terminal of one of the control stages of the regulating element. These stages include a common terminal connected to the positive pole of the source.