Abstract: A standby AC electrical power system connected between a load device and the AC line voltage comprises a voltage responsive control circuit connected between the AC line voltage source and a DC to AC inverter circuit. The control circuit generates a continuously pulsating DC control voltage which has an envelope which responds to and follows but at a different rate the increase and decrease in the envelope of the output of a full wave rectifier fed by the AC line voltage. The control voltage remains above a given triggering level when the average value of the rectified output for the current half cycle involved stays above a given monitored level indicating that the average value of the current half cycle of the AC line voltage is above a given low level and drops to the triggering level when the average value of the current half cycle of the AC line voltage drops to the given low level.

Abstract: An electronic peripheral nerve stimulator which may be used to monitor the type of neuromuscular blocks present in a patient following the administration of a muscle relaxant drug. An integrated circuit monostable multivibrator or one-shot is coupled to an amplifier and output stage. Plural integrated astable multivibrators are provided which may be selectively employed to trigger the one-shot circuit to thereby produce stimulating impulses of several predetermined repetition rates and duty cycles useful for producing the so-called "twitch" and "tetanus" responses of a patient's digital members. The peripheral nerve stimulator also includes indicating means for the power-on condition of the unit as well as for a low battery charged condition.

Abstract: A charging stand for a rechargeable battery pack having a receptacle for receiving a battery pack to be charged and/or tested and having indicator means for providing a visual indication of the condition of the battery pack. The charging stand is adapted to be connected to the output of a standard AC to DC converter and includes a circuitry for applying a charging current to the battery pack as well as sensing and indicating that charging is in progress and that the battery potential is low or fully charged. A manually operated switch is also provided to permit the testing of the condition of a battery pack. When the pack to be tested is inserted into the receptacle in the test stand and the switch is operated, a battery, which is partially discharged, will result in a "low" indication being given, but if fully charged, a "high" indication will result.

Abstract: A transcutaneous electrical nerve stimulator in which a unijunction transistor relaxation oscillator is used to produce variable frequency, variable width pulses. The relaxation oscillator drives a two stage transistor amplifier and the output therefrom is transformer coupled to a set of output electrodes which are adapted to be placed on the area of a patient to be treated. The amplitude of the signals applied to the patient as well as the rate and duration thereof are controllable so that the patient may adjust the nerve stimulation to suit his particular needs.