In today’s world most of the electronic appliances needs DC voltages from 3-12 Volts for operation. An adaptor is a device which is used to convert high AC voltages to low DC voltage. Adaptors come in various shapes, sizes & configuration depending on the use. In some cases adaptors are used to provide power to electronic appliances like video games, modems etc and in some cases they are used to charge the primary battery of the electronic device and also act as alternate power source like mobile chargers, laptop chargers, cell chargers etc. A typical adaptor is shown in the figure below.
The left red knob changes the output voltage while the right one is used to change the polarity of output voltage.
An adaptor works in these 3 simple steps:
1.AC voltage is stepped down using a Transformer
2.A rectifier circuit changes the AC signal to DC signal.
3.A capacitor filters the signal to smooth DC waveform.
On removing the outer plastic body of the adaptor, glimpse of transformer and other circuitry is shown in the image above.