Power Supply, Full-Wave Rectifier, Center-Tap
Circuit Diagram of a Full-Wave Rectifier, Center-Tap
- D1 - Rectifier Diode
- D2 - Rectifier Diode
- T1 - Transformer (Primary 120V, Secondary 8.5 Volts)
- SW1 - SPDT switch (optional)
- C1 - Electrolytic Capacitor (3,300 mF)
How Full-Wave Center-Tap Rectifier Works
The circuit uses a center-tap transformer in combination with two rectifier diodes in order to harness both half-cycles
of the AC current in the transformer's secondary coil. We "tap" a point at the center of the secondary winding and use
it as the common (ground) connection. The primary coil connects to your household AC power outlet. The switch, SW1, is
optional. A stepped-down AC current is induced at the secondary coil. During the first half-cycle of the AC current in
the secondary coil, the current passes through D1 and on througn the load and back to the center-tap connection of the
transformer, T1. During the second half-cycle of the AC current, the current passes through D2 and on through the load,
then back to the center-tap connection of the transformer, T1. The electrolytic capacitor is connected across the output
voltage of the resulting circuit to "smooth down" the fluctuating DC current at the output of the rectifier circuit.
This is a typical effect of putting converting an AC signal to a DC signal. A capacitor is not required for loads that
are not sensitive to significant DC voltage fluctuations.
A full-wave rectifier power supply is twice as efficient as the half-wave rectifier since it utilizes both half cycles of the
AC current, thereby, not putting one-half of the cycle to waste.