Hello,
I have two questions and I’m unsure on how to solve them.
Question 1
A 1KΩ load resistance is connected across a half-wave rectifier. The input supply voltage is 12V (rms) at 50 Hz, a 1000µF filter capacitor is added across the load resistor. Determine:
The ripple frequency.
The ripple factor.
The ripple voltage.

Question 2
Design the full-wave rectifier circuit with the CLC filter, when the ripple voltage is 0.118 V, the input frequency is 50Hz, and the rms voltage for the source is 12V, assuming the load is a pure resistor which is equal to 1KΩ, C1 is 100µF, C2 is 1000µF and the voltage drop across the diode is 0.7V.

 

Start by drawing your circuit and sketching the waveforms you expect to see in sufficient detail to show the parameters you need to measure. Then start analyzing the circuit and putting numbers to those parameters, relating them to the component values.

 

Hello,
I have two questions and I’m unsure on how to solve them.
Question 1
A 1KΩ load resistance is connected across a half-wave rectifier. The input supply voltage is 12V (rms) at 50 Hz, a 1000µF filter capacitor is added across the load resistor. Determine:
The ripple frequency.
The ripple factor.
The ripple voltage.

Question 2
Design the full-wave rectifier circuit with the CLC filter, when the ripple voltage is 0.118 V, the input frequency is 50Hz, and the rms voltage for the source is 12V, assuming the load is a pure resistor which is equal to 1KΩ, C1 is 100µF, C2 is 1000µF and the voltage drop across the diode is 0.7V.

Hello there,

Compared to many other circuits, the seemingly simple rectifier circuits are very hard to analyze if you need *exact* answers mostly because we have to solve for time values as well as voltage (or current) values, but many times we see *approximate* answers that are accepted as good enough, and often times they are not that bad anyway.

So, my question to you is how accurate you need the answers to be. Alternately, what have you done in the past with this kind of circuit and what did you find was acceptable in the past. Knowing this would be an enormous help in order for anyone here to understand what you are required to do to answer these questions.

 

In Question 1, is the 12V rms a sine wave?
In Question 2, is the reading of 0.118V peak, peak-to-peak or rms?
Is the rectifier silicon, germanium or schottky?

 

In Question 1, is the 12V rms a sine wave?
In Question 2, is the reading of 0.118V peak, peak-to-peak or rms?
Is the rectifier silicon, germanium or schottky?

Yes, in question 1 it is a sine wave and in question 2 the rectifier is germanium.

 

Hello there,

Compared to many other circuits, the seemingly simple rectifier circuits are very hard to analyze if you need *exact* answers mostly because we have to solve for time values as well as voltage (or current) values, but many times we see *approximate* answers that are accepted as good enough, and often times they are not that bad anyway.

So, my question to you is how accurate you need the answers to be. Alternately, what have you done in the past with this kind of circuit and what did you find was acceptable in the past. Knowing this would be an enormous help in order for anyone here to understand what you are required to do to answer these questions.

I haven’t had any problems like this before, it was given to us in class with a formula for ripple voltage but upon further research there were different formulas for different filters used and none of them matched the formula given in class. For accuracy, as accurate as possible.

 

I haven’t had any problems like this before, it was given to us in class with a formula for ripple voltage but upon further research there were different formulas for different filters used and none of them matched the formula given in class. For accuracy, as accurate as possible.

Ok, so what formula was given in class?
If they gave you the formula, what is the problem then?
Post the formula(s) and we'll take a look, especially the one they gave you for this.

 

I haven’t had any problems like this before, it was given to us in class with a formula for ripple voltage but upon further research there were different formulas for different filters used and none of them matched the formula given in class. For accuracy, as accurate as possible.

As already stated, this is a very difficult problem to solve analytically.
Hence, approximations are made and "as accurate as possible" is an unreachable goal.

In order to solve this, you need to know the shape of the output waveform and this is not easy.
Take a stab at this by assuming that the shape resembles a saw-tooth wave.
Determine the amount of charge being transferred from the capacitor to the load.

(In my electronics class, we were given the exact same question and no formula or background on how to solve it. We were expected to come up with a solution all on our own, just as you are asked to do.)

Another important question to solve is, What is the peak current through the rectifier?

 

Think about this from a practical point of view. The supply in real life will come from the mains via a power transformer. The mains can vary by ±10%. Transformer regulation may be as much as another 10%. The diode will have a series impedance as well as a voltage drop, and the capacitor will have ESR, all of which influence how fast it charges and how much voltage will be across it.
For anyone designing a power supply, the ripple voltage isn‘t something that needs to be known accurately, and because it is difficult to calculate, no-one does.
Just make the assumption that the capacitor charges to Vpeak in no time at all once every cycle (or half-cycle for a full wave rectifier) and discharges at a constant current for the length of the cycle, and you will be near enough for most purposes.

 

Hello again,

I did not mean to imply that the exact solution was not possible for a capacitor-only filtered rectifier circuit, but it's not usually done in earlier electrical classes. I guess it could be though because this is one of the simpler rectifier problems. The more difficult ones involve things like capacitor ESR and the like.

That would be for the first question.
The second question seems to involve an inductor also.

Another question for the thread starter would be, are you allowed to use a simulator to find the answers.