Abstract: There is disclosed a cathodic protection system current control apparatus incorporating an IR compensator circuit wherein the electric potential between a reference cell such as a copper-sulfate half-cell and the wall of a tank or other structure being corrosion protected is measured in such a way that nearly all of the potential due to IR voltage drop through the electrolyte is compensated for and eliminated leaving only a voltage measurement representing the true electrolytic potential at the cathodically protected object. This true electrolytic potential is utilized to act as a control input for a conventional current controller to maintain the desired electrolytic potential by changing the current passing through the electrolyte. The compensator circuit includes a rectifier device and a capacitor charged by a constant current source, and thus has a much longer response time for rising voltage values than it does for falling voltage values.

Abstract: There is disclosed electronic apparatus for devitalizing a band of cells girdling a tree trunk to cause the death of an unwanted tree or other plant, including a source of radio-frequency energy, and first and second r.f. electrical couplers to the stem or trunk of the plant or tree; preferably such couplers are flexible chains or the like and are caused to encircle the tree by a first actuator which closes jaws of a portable portion of the apparatus around the tree and a second actuator which draws the flexible couplers snug against the trunk of the tree. Death of the plant is believed caused primarily by devitalization of a band of cells girdling the stem of the plant and in particular the cambium cell layers are devitalized by being elevated in temperature by dielectric heating or induction heating effects.

Abstract: A personal security alarm including a loud speaker powered by an audio frequency signal generator to produce a siren effect and a high intensity flashlamp, both of which are activated upon operation of a remote switch and can be deactivated only by a key switch on the alarm. A generally conical transparent plastic extension from the center of the loud speaker horn encloses the flashlamp and also disperses the sound. Preferably the high voltage power for the flashlamp is derived from a transformer supplied with the audio frequency signal provided to the loud speaker.

Abstract: A radio controlled guidance and speed control system for a vehicle has spaced receivers for receiving magnetic energy signals from a movable energy source. The signals received vary in accordance with the position of the receivers with respect to the energy source, and are electrically processed to control separate motors driving two wheels of the vehicle for starting, stopping and direction controlling. The circuit for processing the received signals comprises a summing amplifier for speed control, two differential amplifiers for direction control and a gate connected to the summing amplifier through a comparator to provide a stop signal. The circuit provides for a gradual acceleration of the motors. One of the receivers is connected to the gate for developing a stop signal to prevent utilization of ambiguous signals from the other signal receivers.