Abstract: A temperature sensitive thyristor is incorporated in a relaxation oscillator to provide active temperature sensing. As temperature decreases, the breakover voltage V.sub.BO of the thyristor increases, and when V.sub.BO becomes greater than the supply voltage, oscillations will cease, thus providing a low temperature alarm point. As temperature increases, V.sub.BO decreases and the amplitude of oscillation diminishes, thus providing a high temperature alarm point. This is a "fail-safe" arrangement because component failure also provides a warning condition (absence of oscillation). Frequency of oscillation may also be sensed as an indication of temperature.

Abstract: A temperature sensitive thyristor is incorporated with an astable multivibrator to provide active temperature sensing. Below the switching temperature Tsw of the thyristor, an oscillatory signal is present at the output of the multivibrator. When the temperature exceeds Tsw, oscillation ceases because of the shunt path provided through the thyristor when it intrinsically switches to its low resistance on state above Tsw. Cooling results in resumption of oscillation. This is a "fail-safe" arrangement because component failure also provides a warning condition (absence of oscillation).

Abstract: A chopper for adjustably controlling the average value of the voltage supplied from a D.C. battery source to a motor load for adjustable speed control. The chopper comprises manually-operable spring-biasing means for applying force to close a contact to energize the motor and electromagnetic means simultaneously energized for re-opening the contact. This occurs at a high repetition rate so that the average value of the voltage across the motor determines the motor speed. This average value of voltage is proportional to the closed-to-open time ratio of the contact and is adjustable by manual control. Two versions are disclosed. In the first version, the spring-biasing force is applied to the contact by depressing a trigger. In the second version, the spring-biasing force is applied to the contact by rotation of a knob. Both versions may use either tension or compression spring force.

Abstract: Thermally sensitive silicon thyristors capable of intrinsically switching between high and low resistance states in response to a predetermined temperature in the range -30.degree. C to +150.degree. C; this intrinsic switching temperature being not only lower than heretofore achieved but also predictably determinable. The two terminal breakover voltage is nominally equal to one-half Vmax at a temperature less than 50.degree. C, where Vmax is the maximum value of the two terminal breakover voltage of the thyristor with respect to temperature.

Abstract: A semiconductor device is disclosed comprising a temperature sensitive thyristor thermally coupled to a power switching thyristor and electrically connected in parallel with the gate of the latter. The temperature sensitive thyristor senses the temperature of the power switching thyristor and automatically responds thereto above a predetermined temperature by shunting the gate current to prevent overheating of the power switching thyristor. The device may additionally include a second temperature sensitive thyristor having a lower switching temperature than the first mentioned thyristor and connected in series with the gate of the power switching thyristor whereby the latter may be triggered into conduction only within a defined temperature range bounded by the switching temperatures of the temperature sensitive thyristors. Normally off and normally on devices are also disclosed.

Abstract: A monolithic semiconductor device is disclosed comprising a power switching thyristor and a temperature sensitive thyristor integrated on a common substrate. In preferred form, the temperature sensitive thyristor is electrically connected between the gate terminal and one of the main terminals of the power switching thyristor, and is thermally actuatable to intrinsically switch from a high to a low resistance state above a predetermined temperature of the power switching thyristor sensed through the common substrate, whereby to shunt gate current and automatically inhibit turn-on of the power switching thyristor to prevent overheating thereof. Depending on circuit variations, the power switching thyristor may be rendered conductive above or below a predetermined temperature, or within a defined temperature range. Normally off and normally on devices are disclosed.

Abstract: Germanium semiconductor temperature switches are described which are capable of intrinsically switching between high and low resistance states within a temperature range up to 55.degree.C, and are adapted for operating at voltages up to 400 volts. These temperature switches are disclosed in various configurations. Basic circuits for adjusting the temperatures at which such switches switch within a range are disclosed. Preferred methods of making the same are also disclosed.