Electronic heat detector circuit for flat radiators - uses Wheatstone bridge with one branch formed by radiator heat sensor, while another branch contains room temp. sensor

摘要

The circuit is intended for detaching heat emitted by flat radiators during a selectable time period. The radiators carry temperature sensors, firmly screwed at a specified height and connected in series. This series connection form a branch of Wheatstone bridge, whose other branch is formed by a room temperature sensor. The bridge supply voltage is provided by a pulse generator at discrete, equidistant time points only. The generator triggers a scanning and hold circuit, which supplies the bridge diagonal voltage during the time period between two voltage pulses. The output voltage of this circuit is converted into a pulse train by a voltage-frequency converter, the pulse train frequency being proportional to the voltage. The pulses are integrated by a counter. Pref. the series-connected temperature sensors are NTC resistors with practically linear temperature dependence.