Pigeon-loft ventilation with control of fan speed - governed by two=stage triac circuit with temp.-dependent resistor and photoresistor responsive to oxygen demand

摘要

The fan is driven by a motor (8) supplied from 220 V mains (9) via an on/off switch with a monitor lamp (3). The control circuit (2) incorporates a rotary selector (6) of resistance inserted between an adjustable resistor (7) and a series combination of an NTC resistor (4) and a photoresistor (5). The adjustable resistor (7) sets a basic fan speed dependent on the size of the loft, for modification in accordance with the temp. and brightness to which the other resistors (4,5) are respectively responsive. ADVANTAGE - Optimal ventilation guaranteed with adjustments in response to daylight and temp. variations.