Apparatus for transmitting the output of a musical instrument for amplification

Claim 1

A portable transmitting unit for use with a musical instrument comprising: a vibration detecting electrical transducer mounted on said instrument; a first amplifier stage including a first transistor of p-n-p conductivity type, a first capacitor connected between said transducer and the base of said first transistor, a first bias resistor connected between ground and the emitter of said first transistor, a source of d.c. energy one side of which is connected to ground, a second bias resistor connected between the ungrounded side of said source of d.c. energy and the collector of said first transistor; a second amplifier stage including a second transistor of the p-n-p conductivity type, a first coupling resistor connected between the base of said first transistor and the emitter of said second transistor, a second capacitor connected at one side to the emitter of said first transistor, a third capacitor and a second coupling resistor connected in parallel, the parallel connection of said second coupling resistor and said third capacitor being connected between the other side of said second capacitor and the collector of said second transistor, means directly connecting the collector of said first transistor to the base of said second transistor, a third bias resistor connected between ground and the emitter of said second transistor, a fourth capacitor connected in parallel across said third bias resistor and constituting an r-f bypass for said second transistor, a fourth bias resistor connected between the collector of said second transistor and the ungrounded side of said source of d.c. energy; an oscillator and transmitter stage including a third transistor of the p-n-p conductivity type, a fifth bias resistor connected between the ungrounded side of said source of d.c. energy and the base of said third transistor, a sixth bias resistor connected between ground and the base of said third transistor, a fifth capacitor connected in parallel across said sixth bias resistor, a sixth capacitor connected between the collector of said second transistor and the base of said third transistor, a seventh bias resistor connected between ground and the emitter of said third transistor, a tank circuit consisting of a seventh capacitor and a variable inductor connected in parallel and connected between the ungrounded side of said source of d.c. energy and the collector of said third transistor, said tank circuit functioning to cause said oscillator and transmitter stage to provide an oscillation signal the frequency of which is within the frequency reception band of a nearby f-m radio receiver, said variable inductor also constituting a radiating means for radiating said oscillation signal into the air, an eighth capacitor connected between the collector and emitter of said third transistor to effect frequency modulation of said oscillation signal with the amplified signal from said transducer; a ninth capacitor connected in parallel across said source of d.c. energy and constituting an a.c. bypass for said source of d.c. energy; whereby the radiated oscillation signal is detected and the vibrations of said musical instrument are reproduced and amplified by said f-m radio receiver.