In electronics prior to the development of switching power supplies and the introduction of semiconductor devices operating at low voltage, it was necessary to generate voltages of about 50 to 250 V of the vehicle batteries. Electro-mechanical components known as vibrators were used in a circuit similar to modern solid-state inverter circuits to provide a pulsating DC that could be converted into a higher voltage with a transformer, rectified and filtered to create higher voltage DC. This "vibrator" is essentially a relay that uses normally closed contacts to supply power to the relay coil, thus breaking the connection immediately, only to be reconnected very quickly through the normally closed contacts. It happens so fast that it vibrates, and it sounds like a buzzer. This same fast pulse contact applies the DC up and down voltage to the transformer that can be raised to a higher voltage.
The main use of this type of circuit was to operate vacuum tube radios in vehicles, but also used other mobile electronic devices with 6 or 12V accumulator, especially in places without power supply like farms. These vibrator power supplies became popular in the 1940s, replacing the more bulky motor-generator systems for the generation of AC voltages for such applications. Vacuum tubes require plate voltages ranging from about 45 volts to 250 volts in electronic devices such as radios. For portable radios, headphones and similar equipment, B batteries were manufactured with varying degrees of voltage. In order to provide the voltage needed for a typical 6 or 12 volt DC source available in a car or on a farm lighting battery, it was necessary to convert the constant DC source to a pulsating DC and use a Transformer to increase the voltage voltage.
Vibrators often experience mechanical dysfunctions, being constantly in motion, like springs that lose tension, and the points of contact wear out. [3] As the tubes began to be replaced by electrical systems based on transistors, the need to generate such high voltages began to decrease. Mechanical vibrators dropped out of production near the end of the 20th century, but solid state electronic vibrators are still manufactured to be backward compatible with older units.