GB1275566A - Improvements relating to electric control circuits - Google Patents

Abstract

1275566 Releasable fastenings T M MARGESON and H W DENNY 12 Aug 1969 [15 Aug 1968] 40229/69 Heading E2A An electrical control circuit includes a single frequency generating means 16 forming a first part of said circuit, single frequency matching means 32 forming a second part of said circuit for receiving said single frequency and generating a control signal when said single frequency is received, each of said frequency means including a crystal control element for permitting precise frequency matching, the control element of the first part of said circuit being insertable therein or removable therefrom to activate or deactive the circuit respectively. As shown the means 16 is connected to an amplifier unit 26 which amplifies the oscillations from the means 16 and these are passed along a co-axial cable 28, 30 to the means 32 the crystal control element of which has the same operating frequency as the crystal control element 22 of the means 16 thus the means 32 will only pass a signal through it when the element 22 is in the means 16; from the means 32 the signal is passed through a unit 34 where it is amplified and subsequently rectified and the resulting direct current is carried along lines 36, 38 to the control gate of a thyristor 42 the signal turns the thyristor on so that a relay 46 is energised to cause its contacts 50 to close to control a load connected to the contacts by lines 54, 56. The circuit can be used for controlling the operation of the ignition coil of a motor vehicle in which case the element 22 is mounted in a member similar in shape to a key and which can be plugged into a socket connected to the remainder of the circuit; the member shaped like a key also acts to connect a battery to the circuit when it is plugged into the socket as well as connecting the element 22 into the circuit. The circuit can in addition be used to control a bonnet lock which is only released when the key shaped member is in the socket so that the circuit cannot be bypassed. All the components of the oscillator unit except the crystal and the first amplifier unit can be mounted on the socket with the remainder of the circuit connected to the socket by the co-axial cable.