Centre Tap Transformer Question

Thread Starter

Zaraphrax

Joined Mar 21, 2009
49
Hi there,

I'd appreciate if you could check my answer. I only require a simple "right" or "wrong". Thanks.

I need to determine the ripple peak to peak voltage and the average voltage for this transformer, that has a 100 ohm load connected. Voltages supplied are RMS values.





Here's what I've done:

Time constant on capacitor: CR= (100 x 10^-6) x 100 = 10ms

Since RMS voltages are supplied, 12 * (2^0.5) = ~17V

Plotting the output of the circuit (and the capacitor discharge curve), I determined that the average voltage was about 14.5V (~12V minimum to 17V), with a ripple of 5 V.

Is this correct?

Thanks.
 

t06afre

Joined May 11, 2009
5,934
I have not checked your numbers. But did you use 50 or 100 Hz then you calculated the ripple? You use a full wave rectifier and then you have to use mains frequencyX2
 

mik3

Joined Feb 4, 2008
4,843
If you assume that the ripple voltage is small then it can be approximated by a triangular wave.

Thus the ripple frequency is:

Vripple=Vaverage/(2fCR)

Vaverage=Vmax-Vr/2

by using the two above equations you get:

Vaverage=Vmax/[1+1/(4fCR)]

f=mains frequency

Check your results.
 

Thread Starter

Zaraphrax

Joined Mar 21, 2009
49
Thanks guys. The question actually doesn't give a mains frequency, so I'll just assume 50hz since thats what our main is over here. Thanks.
 
Top