ID: 
2088
Maker's Name: 
Ferrocart (A'asia) Pty Ltd
Where made: 
Australia
Dimensions: 
3.7 × 3.7 × 9.4 cm

This mechanical vibrator was specifically designed for the Australian military WWII portable radio equipment.

This vibrator has a steel reed with two isolated halves. The primary and secondary contacts are independent. The reed is driven magnetically by a make and break contact on the reed applying 12 Volts DC to a coil around a steel pole. It cycles at 100 Hertz. The vibrator contacts apply 12 Volts on the primary side of a transformer to the ends of a centre-tapped winding alternately. Synchronously with the primary contacts, contacts on the secondary side of the transformer close to apply the secondary voltage to the radio from the ends of a centre-tapped secondary winding alternately. The secondary output voltage is around 200 Volts DC.

This synchronous arrangement means the system is self-rectifying, requiring no diodes on the transformer secondary. The secondary contacts take the place of the diodes.

Maintenance of the contacts requires a diamond dust wiper to clean and smooth the contacts. Using pointed-nosed pliers, adjust the primary contacts by bending the contact arms so the contact clearances are as near as possible the same. Apply power and adjust the make/break contact to get a pure vibration note. Adjust the secondary contacts to get a maximum secondary voltage. Adjust the value of the buffer capacitor/s across the transformer secondary/ies to get minimum sparking on the secondary contacts (the capacitor/s and secondary winding/s form a tuned circuit, set to the same frequency as the reed). There is also a capacitor across the primary circuit, which tunes the primary winding. Replace this if primary contacts spark excessively. The value of this capacitor may need to be adjusted.