This invention relates to a circuit for monitoring the presence of a flame of a gas burner, comprising a probe means connectible to a source of alternating signal and locatable in a combustion area of the flame for applying said alternating signal across the area for rectification by the flame when the flame is present, second means operably coupled to said probe means for providing a second alternating signal in dependence upon the generation of the rectified signal, and switch means connected ...

An inverter for supplying alternating current to a load from a direct current supply including a thyristor bridge for connecting the phase load or loads between the terminals of the direct current supply through respective inductors, or parts thereof. A flywheel diode bridge is also provided for returning energy induced by the load to the power supply. A commutation circuit, including a commutation capacitor is arranged for inducing thyristor turn-off voltage pulses in the inductors. The compone...

Printed circuits are produced by an additive technique wherein a metal-loaded resinous ink is first printed on the board, the circuit next being covered with a conductive metal powder while the ink is still wet. The powder is then pressed into the ink and the circuit cured. Next, a solder stratum is alloyed with the powder as by a solder paste printed over the circuit and the board heated to cause the solder to alloy with the ink and powder substrates. A solder resist may then be applied selecti...

Matrix circuit for obtaining a third color difference signal from first and second color difference signals demodulated in a color television receiver, a level compensation circuit rendering the levels of the three color difference signals independent from one another without the use of control loops and by using only two level detection circuits.

Ink compositions especially suitable for printing electronic circuit patterns on a substrate such as a flexible polyester substrate; methods for developing electrolessly and electrolytically the circuit configurations as articles of manufacture; flexographic printing with the ink composition has been disclosed as the preferred method.

A control circuit for controlling the operation of an electrically powered heating device includes supply terminals for connection to a source of d.c. supply, one of the terminals of the heating device being connected to one supply terminal and the other terminal of the device being connected to the other supply terminal by way of a relay contact. The junction of the contact and device is connected by way of a resistor to one plate of a capacitor the other plate of which is connected to the one ...

The buffer circuit is provided with a high sensitivity balanced type flip-flop circuit and a capacative coupling provided by MOS capacitance, and a load drive circuit utilizes bootstrap effect, thus producing complementary signals having a MOS level from a TTL address input signal.

A circuit is disclosed for use in telephone handsets having a line signal node (1), a microphone signal input (20) and an output to an earphone amplifier. There is provided two voltage feedback loops via respective impedance networks (10, 11) and a current feedback loop (5, 7, 14). These feedback loops determine the impedance presented to the line at the signal node with specific voltage/current characteristics and signal frequencies. The first voltage feedback loop in conjunction with the curre...

An integrated circuit having a built-in self test facility, the integrated circuit being partitioned into a number of sub-circuits each of which comprises a combinatorial logic circuit and a register. The sub-circuits are coupled together so that each combinatorial logic circuit has its inputs coupled to at least one register, has its outputs coupled to at least one register, and the output of the overall integrated circuit is taken from one or more registers. Each register has its fucntional mo...

Disclosed is a technique for the protection of micro-electronic circuits. A room temperature vulcanizing silicone rubber is applied over the circuit. While the rubber is in an uncured state, a solvent-resistant cover coating is applied thereon. The resulting structure is then treated so that both layers cure simultaneously. The resulting dual layer provides protection against contaminants and solvents used in the circuit fabrication. In addition, mechanical protection is provided for crossovers ...