Abstract: The photocathode of an image intensifier is pulsed ON and OFF at a rate determined by a thyristor or SCR having the anode to cathode path coupled to the photocathode and the gate electrode triggered by a variable resistor, capacitor (RC) circuit to cause the photocathode to draw or conduct current only during the OFF interval of the SCR. During the ON interval of the SCR, the photocathode is OFF or non-conducting, wherein the controlled image intensifier tube exhibits a relatively constant resolution over a wide range of input light input values as from 10.sup.-6 to 10.sup.1 foot-candles.

Abstract: The present invention is a knob which attaches to the switch post of a push/pull switch. The knob selectively disengages from the switch post as the knob is inadvertently impacted, thereby isolating the push/pull switch from the impacting force. The knob moves independently of the switch post and contacts the housing supporting the switch. Consequently, the force of impact is directed to the housing through the body of the knob and very little force is directed to the switch.

Abstract: A bright source protection circuit for an image intensifier tube modulates the voltage supplied to the tube's photocathode in response to current drawn by the photocathode such that the photocathode is pulsed on and off until the desired photocathode current is achieved.

Abstract: An improved battery pack for night vision goggles is employed in the cockpit of an aircraft, where RF fields of several hundred volts/meter are present. The improved battery pack includes a shunt circuit for shunting RF signals picked up by any external leads from the battery pack, and a resistor for dissipating electromagnetic energy from the RF signals shunted by the shunt circuit.

Abstract: An image intensifier tube having an electromagnetic interference protection arrangement. The protection is accomplished by shielding the tube and filtering the power supply. Shielding is performed by means of a conductive metallic coating which surrounds the image intensifier tube housing. Filtering is accomplished by using capacitors to short the interference to ground.

Abstract: There is disclosed a high light level cutoff apparatus for use with night vision devices. The apparatus employs a digital method of timing implemented by a divider counter responsive to a crystal controlled input frequency which essentially controls a latch to produce an automatic shutoff of a night vision device during high light ambient conditions which conditions would undesirably reduce the effective life of such a night vision device. The circuitry disclosed utilizes a digital method of clocking and employs the latching relay as indicated which is operated by the digital counter. The circuitry provides a feed back from the latching relay which resets the night vision system so that it will re-operate if a transient accidentally serves to operate the goggles while the light level is in a high state.