In the exemplary embodiments, the processing circuit for supplying the stimulation pulses comprises a series arrangement of capacitors which are chargeable in parallel and dischargeable serially. The goal of the disclosure, given such a heart pacemaker, is to see to the greatest possible variability of the output amplitude given the lowest possible technical outlay. This goal is inventively achieved in that program switches are allocated to the capacitor circuit for interconnecting or, respectively, disconnecting individual capacitors in combination randomly prescribable as needed for parallel charging and/or serial discharge, said interconnection or, respectively, disconnection occurring according to programs of a program generator.

An analgesic noise generator employs a transistor operated to provide a zener action that is broadcast as the active noise source in an integrated circuit amplifier packaged as a portable unit with means to control tone and volume and enhance life of the power source.

A pulse generating circuit suitable for use in an implanted cardiac pacer is described. In its simplest form, the invention comprises a long life, direct current energy source which is connected to an astable multivibrator which produces output pulses of a predetermined duration at a prescribed frequency. Connected to the output of the multivibrator is a voltage multiplying circuit which serves to increase the amplitude of the output pulses from the multivibrator. By employing a novel constant current source in the multivibrator, extremely stable operation is obtained over the useful life of the battery. Further, because of the novel design of the voltage multiplier circuit, the overall efficiency of the pulse generating circuit exceeds that of known prior art devices designed for a similar purpose.

Apparatus for stimulating body tissue and in particular the heart, is disclosed as including a device or circuit responsive to the initiation of stimulation and/or to the failure or pending failure of a component of the stimulating apparatus to provide the patient with a perceivable stimulation to a second, different portion of body tissue. There is disclosed an impedance level detector for sensing the impedance presented between the outputs of the stimulation apparatus to provide a warning signal indicating that the output impedance falls outside a predetermined range. In particular, the impedance level detector output is sensed by a stimulation control logic to apply a first train of pulses at a first rate to an auxiliary electrode for stimulating the second portion of tissue. Further, there is included a voltage level detector for sensing when the power source voltage depletes below a predetermined level, to actuate the stimulation control logic to provide a second train of warning pulses to the auxiliary electrode, at a second, different rate than that of the first train. In this fashion, the patient not only is warned as to the pending failure or failure of a component of his pacemaker, but also is able to identify the failing component.

A free running oscillator clocks a counter, which produces stimulation control signals at a predetermined counter. An output stage includes transistors, energized by the counter, to issue stimulating pulses having a voltage equal to that across a capacitor in parallel with the output stage. The output capacitor is charged, between output pulses, by successive charge sharing cycles with at least one other capacitor, which is enabled by a stored program word, at a rate determined by the oscillator output cycles.