Voltage | Vintage Electronics Blogsphere

Archive for the ‘voltage’ tag

Full Wave Rectifiers

Full Wave Rectifiers
What is the peak diode current in a full Wave Rectifier circuit?

I have a question in tutorial where I need to find the peak diode current in a rectifier circuit which has a full wave rectifier, a 50V peak A.C. signal at 50Hz and smoothened by the use of a capacitor of 47uF and a resistor of 4.3kohms.

Help would be much appreciated

Assuming 0.8 volts dropped in each diode, the output voltage would be 48.4 volts, The resistor current would be 48.4V/4.3 k or 11.25 milliamps. This is the average current. After the peak of the sine wave the capacitor will discharge for nearly 10 milliseconds. The RC time constant is 0.20 seconds, after 9 milliseconds V load resistor = 48.4(exp ^-(0.009/0.2) = 46.3 volts. Current starts to flow through the diodes when the peak voltages is about 48 volts or when the sine wave is at 73 degrees. Which occurs 1 millisecond before the maximum peak. Thus the average 11.25 milliamp current must flow for only 1/10 the cycle so the instantaneous current must be 113 milliamps.