Vinyl Asylum: Re: From Dr. Win's Manual: Theory Of Operation: by Vinylly

"The SDT (Semiconductor Disc Transducer) operates as a modulating devise. It does NOT contain coils or megnets. It consists of two semiconductor strain-gauges connected within cantilevered beams. This semiconductor element is specially treated to become more or less conductive under small pressures and strains, thus changing the resistance of the element.
The stylus beam, through it's linkage, flexes the strain-gauges in proportion to the applied force. Since this change in resistance does not create an output voltage, a DC bias current is fed through the strain-gauges from the external power source. The silicon element thus acts like a valve, with a consequent change in current at efficiencies 10,000 times those of velocity magnetics".

THE POWER SOURCE:
"The SDT is accompanied by a specially designed and electronically matched power source. It supplies a regulated DC voltage limited to 6ma bias to each of the semiconductor strain-gauges. The output voltage from the strain-gauges is then AC coupled to a low noise FET bipolar hybrid preamp of the power source. This amplifies the signal to approximately 0.8 vrms at 3.54 cm/sec to match the high level inputs. This is done because the SDT has an RIAA equilization in its mechanical design, and a phono preamp would over-compensate the frequency responce. The power source will also supply, without loss of frequency response, a minimum signal of 0.4 vrms into a 600 ohm load".
(I'm not an electrical engineer so I can't comment on the details, however, from the illustraitions of the strain-gauges as compared to both mc and mm cartridges, it seems extreamly simple. The cart. seems to be made up mostly of the plastic shell. This also explains it's very light weight.)