Transcutaneous nerve stimulator

Claim 1

A transcutaneous nerve stimulator comprising in combination: (a) an astable multivibrator having a first resistance/capacitance timing circuit for controlling the frequency of the output pulses produced by said astable multivibrator and a second resistance/capacitance timing circuit for controlling the pulse width of said output pulses; (b) semiconductor current control means coupled by variable impedance means to receive said output pulses from said multivibrator; (c) a source of direct current voltage connected to said multivibrator, said first and second resistance/capacitance circuits and to said semiconductor current control means; (d) a transformer having a primary winding connected in series with said semiconductor current control means, the series combination being connected across said source of direct current voltage, and a secondary winding; (e) means coupling said secondary winding to first and second pairs of output terminals to which stimulator electrodes may be connected; (f) a third resistance/capacitance timing circuit connected across said source of direct current voltage; (g) a voltage divider connected to said source of direct current voltage for sensing the magnitude thereof; (h) indicating means connected to said voltage divider; and (i) a second astable multivibrator energized by said source of direct current voltage having an output terminal coupled to said indicating means and a trigger terminal connected to said third resistance/capacitance timing network, whereby said indicating means is continously energized when the magnitude of said direct current voltage is above a predetermined level and is alternately energized and deenergized when the magnitude of said direct current voltage drops said predetermined level, at a rate determined by said third resistance/capacitance timing circuit.