In the later twenties, the radio receiver power supply comprises a set of batteries. Thus, while the A battery supplies the voltage for the valve filament, the B batttery supplies the high voltage and low current for the screen and plate, as known as B (+).
Also a C battery could be used when the power supply used separated bias for the screen.
Fig. 317 - The vibrator a kind of component developed to converter the 6 V CC into high voltage CC.
Such a kind of power supply had several disadvantages: the size as well as the voltage and current required for the B (+). Thus, during the early thirties, a demand ocurred in the radio industry for a substitute of the “B” battteries. Firstly, engineers investigated the possibilities of the motor generator as known as dynamotor. Therefore, due to its size and high manufacturing cost it was unsuitable for such application.
In this way, after many researches, finally it was developed a kind of half-wave buzzer connected to a transformer and a rectifier valve as known as a power supply using a vibrator.
In the following years various types of vibrators were developed such as: the full-wave non-synchronous vibrator and the full-wave, self-rectifying one. Practically these units were used to convert 6 V DC to hight voltage DC.
In the beginning the due to its size and high efficiency, the synchronous vibrator with an incorporated rectifier valve was the most often used unit.
Therefore in order to overcome some difficulties found during the unit operation, since 1932 the vibrator was supplied with a separted rectifier valve. Fig 317
Originally the first valves developed in the USA to be used with vibrator for automobile application were mercury vapour half wave rectifiers which were soon replaced by the high vacuum full wave types.
Since then, the power supply-using vibrator was adopted all over the world up 1960 with the lauching in the market of the first solid-state radios.