MOVING IRON MICROPHONE, 1930's

Probably just a toy for adults or early learners, the unit is of the carbon type. In the base is a matching transformer, and the primary element requires 1.5 volts to operate.
In use it has a unique sound like an early wireless broadcast.

Your comments:

• Made using an ex-GPO 'solid-backed' carbon granule microphone - a GPO 'Transmitter No 1' made in this case by Automatic Telephone Manufacturing Co of Liverpool (indicated by the GPO Manufacturer's code letter 'H' in 1926 (hard to make out the last digit). As used on pillar(candlestick) and wooden wall telephones until introduction of the Transmitter No 22 with removable 'Transmitter Inset No 10' c1930
  .......... Ian J, North Wales, 18th of December 2015
  
  

A0317