Abstract: A non-toxic, non-chemical, non-polluting, inexpensive electronic apparatus (10) which controls the fly population within an animal or poultry enclosure which kills by destroying the nervous system of the fly with a short pulse of a high voltage that is applied to a pair of conductors (80) and (81) every 1 to 5 seconds.

Abstract: Normally closed ventilating elements of a poultry building or the like are opened in response to failure of the supply of electric power to the building ventilating system by a control system which includes a source of direct current electricity arranged so as normally to energize an electromagnet and thereby to secure its armature to the electromagnet. The armature is secured to the handle of a winch which is arranged to operate the building shades. Power to the electromagnetic device is controlled through a MOSFET acting as a switch and which is controlled by a parallel combination of a capacitor and a resistor which are connected in parallel with the MOSFET gate. When power is lost, the capacitor discharges through the resistor and deenergizes the electromagnet so as to free its armature to rotate with the winch handle to open the building curtains.