Looking at the circuit diagram, the ferrite rod antenna is tuned by variable capacitor C1, with the selected signal coupled into the base of TR1.  TR1- 4 form an untuned RC-coupled RF amplifier followed by transistor detector TR5.  TR6, wired as an emitter follower, drives the magnetic earphone.  Waveband switching is accomplished by switch B1 shorting out part of the aerial winding in the medium wave position. The AGC voltage developed at the detector's base controls the gain of TR1.  Being non-regenerative the circuit is stable and results in a receiver more easily used by the layman. This type of circuit was incorporated some years later in the legendary ZN414 radio IC.  Anyone who's used regenerative reflex designs will know that they need skillful setting up to get the best from them.  Specifications are as follows: Power supply, 1.2v NiCad or 1.5v disposable button cell; Coverage 150-408kHz LW, 525-1605kHz MW; Sensitivity 35mV/m, Battery consumption 4mA, power output 50uW.  The case is glued together so I haven't a pic of the works.