Half wave rectifier
- Diode converts ac input voltage to a pulsed dc output voltage.
- Whenever the ac mput becomes negative at diode’s anode. the diode blocks current flow. o/p voltage become zero.
- Diode introduces a O.6V drop so o/p peak is O.6V smaller than the i/p peak.
- The o/p frequency is same as the i/p frequency.
Full wave rectifier
- A full-wave rectifier does not block negative swings in the i/p voltage, rather it transforms them into positive swings at the o/p.
- To gain an understanding of device operation. follow current flow through pairs of diodes in the bridge circuit.
- It is easily seen that one pair (D3-R0-D2) allows current flow during the +Ve half cycle of Vin while the other pair (D4-R0-D1) allows current flow during the -Ve half cycle of Vin.
- o/p voltage peak is 1.2V below the i/p voltage peak.
- The o/p frequency is twice the i/p frequency.
ac to dc supply :
- An AC2DC power supply is built using a transformer and a full-wave rectifier.
- Transformer is used to step down the voltage i/p.
- Rectifier converts AC to pulsed DC.
- A filter capacitor is used to smooth out the pulses.
- Capacitor must be large enough to store sufficient charge so as to provide a steady current suppiv to the load:
RLoad C >> 1/f,
f is rectified signal’s frequency (120Hz).
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