A dual range differential current switch including a differential switch pair of transistors having first and second complementary control inputs which receive first and second complementary signals so as to be controlled by a control signal with equal delay from a clock signal. A first set of switching transistors is coupled to provide the first complementary signal which controls the first complementary control input of the differential switch pair. A second set of switching transistors is coupled to provide the second complementary signal which controls the second complementary control input of the differential switch pair. First delay transistor pairs are coupled to the complementary outputs of the cross coupled inverter and have the characteristic that the fall times of its outputs are greater than the rise time of its outputs. Second delay transistor pairs are coupled to the first delay transistor pairs and have the characteristic that the rise times of its outputs are greater than the fall times of its outputs. The second delay transistor pairs are coupled to the first and second sets of switching transistors such that a first output of the second delay transistor pairs provides a first input signal to the first set of switching transistor pairs and a second input signal of the second set of switching transistor pairs, and a second output of the second delay transistor pairs provides the second input signal to the first set of switching transistor pairs and the first input signal of the second set of switching transistor pairs

A dual-range pressure switch apparatus has a piston member disposed in a switch mechanism containing chamber sealingly pertitioned by a diaphragm in the inner space of a housing, and being movable in the axial direction of chamber. A high-pressure snap disk is placed on the side surface of piston and contacts the diaphragm. In the chamber, a low-pressure snap disk is so arranged that its outer rim engages with the inner periphery of chamber and sandwich the piston between its center and the diaghragm. When the pressure of a pressurized fluid introduced in the inner space is lower than the lower limit of a certain range of values, both low and high snap disks are stable, so that paired resilient switch pieces disposed adjacent to the low snap disk in the chamber separate from each other. When the pressure is set in the certain range, only the low snap disk is transformed to push one switch piece to make it contact the other. When the pressure becomes higher than the upper limit of certain range, the high snap disk is then transformed to push a rod inserted through the piston and the low snap disk, so that the other switch piece is separated from the former transformed one switch piece.

A dual range vacuum switch in which the diaphragm movement with increasing vacuum is opposed by two springs which determine the vacuum required to actuate the switch. As the vacuum subsequently decreases one of the springs is rendered inoperative before the switch resets so the reset vacuum is determined by the one spring remaining effective. The spring which is rendered inoperative is compressed between the actuator and an eyelet which can seat on the actuator (spring ineffective) or the housing (spring effective) and which also functions to limit motion of the actuator relative to the eyelet so the switch operated by the actuator cannot be overstressed.