Chopper (electronics)

The term referred to in the electrical vibrator, an electromechanical device, which serves to generate a DC voltage a square-wave AC voltage to then transform these to. Because of their susceptibility to error, they were replaced by transistorized inverters in motor vehicles.

Also fluorescent lamps could be operated using such a mechanical inverter DC voltage.

Another application is to change the direction of weak signals in order to amplify drift-free with the help of AC voltage amplifiers can. For such application, the electro-mechanical solution is advantageous because active electronic components arbitrarily small voltages can not necessarily turn.

Chopper today are no longer in use. They have been functionally replaced by switching power supplies or inverters, which with semiconductor switches such as transistors work.

However, be choppers in different versions, since they can easily be built with commercially available relay, occasionally used by hobbyists for generating high voltages with batteries.

Function

The DC voltage (typically 12 or 24 V) in this case flows through a coil ( electromagnet) which actuates a switch on an armature, interrupts the circuit to the coil. However, the switch closes again, as a restoring spring back to move the armature, resulting in a new current flow. The result is a periodic closing and opening the switch with eg 50 Hz ( principle of Wagner's hammer as well as in DC-operated electric bells or radio inductors ).

One or more additional contacts generate an AC voltage in a transformer, on the required voltage (for example, the anode voltage) is transformed. After the secondary winding can be obtained by the same chopper with further contacts also a rectification done ( synchronous rectifier ). Simple devices for low currents carried the secondary winding directly to the stimulating coil.

Such chopper are no longer in use due to the noise, the low life and sparking ( spurious emissions ). They were replaced by transistorized inverters.

They were once used to (eg in vehicles ) to operate tube devices (radios, taxi radios) even from batteries. The choppers were equipped due to their wear with a plug-in base to easily replace at end of life can.

Vibration generation

The device shown is an inverter that can produce an AC voltage of 220 volts from a DC voltage of 6 volts (on-board voltage older passenger cars). Meanwhile circuit shown above is explained below:

Transformation

The positive pole of the supply voltage is less alternately at rest and working contact of the switch. The two winding halves of the transformer are thereby connected alternately to the DC voltage. Their winding sense is such that the primary side ( left side ) of the transformer, an alternating voltage is produced. In the secondary winding, an AC voltage of typically a few hundred volts is induced. This can be rectified with a rectifier ( or a further pair of contacts of the chopper ), and serves as the anode voltage. The capacitor on the secondary side in the picture above is for debugging, but especially the reactive current compensation; he is such that the contact load (switching sparking ) is minimized.