It comprises of a spring mounted steel vibrator arm which carries a contact connected in series with a solenoid. The free end of the vibrator carries a marking point which strikes the paper tape through a
disc of carbon paper, thus making the tapes once for each oscillation. It works on 6-9 volt, 1Amp. A.C. power supply. The instrument is mounted upon a thick bakelite base and 4 mm brass socket terminals
are provided for electrical connection. Complete with one dozen round carbon papers and roll of aper strip alongwith AC power supply of 6V to 9V, 1A.