(4) A rectifier circuit converts AC voltage to DC voltage. A bridge rectifier ci
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Question
(4) A rectifier circuit converts AC voltage to DC voltage. A bridge rectifier circuit consists of 4 diodes and a capacitor as shown below (the circuit on the left). This circuit's operation can be simulated by the circuit on the right. The switch in this circuit is closed momentarily over a very short period of time every 1/120 second. This short interval is long enough to charge the capacitor voltage Vo(t) to Vs (since the Rs is very mall so the charging time constant is very short). The purpose of the capacitor is to 'hold' the voltage Vo(t) over the time period 1/120 second while the switch is open. A resistor RL 10?, is used to simulate the circuit (such as a stereo amplifier circuit) that draws power from the capacitor. Find the minimum value of the capacitor (in Farad) such that Vo(t) does not drop below 95% of Vs over the time period of I/120 second If the capacitor is too small, the 120Hz 'ripple' on the Vo(t) can be high enough to cause problem. In the case of a stereo amplifier, this ripple can cause the 'hum' noise from the speaker which is a common problem for older amplifiers where the capacitors deteriorated over time and the capacitance decreases to a fraction of its designed value. Rs Vs AnswerExplanation / Answer
The minimum value of the capacitor can be calculated using the formula
Vdc = vm(1-(idc/4fC))
Where Vm is the maximum voltage obtained after diode rectification. That is input to the filter. Here the frequency should be considered as 60hz because ripple frequency will be 2*input frequency =120hz.
Make sure that ripple voltage is not greater than 1.0 V. That that your required parameter is achieved.
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