half wave rectifiers and ripple factor

Thread Starter

micachu

Joined Oct 13, 2014
15
We constructed the circuit below
upload_2015-3-1_14-53-6.png
and when measuring the output we got a ripple factor of abut 25%.
upload_2015-3-1_14-54-30.png

We then added a 10 ohm resistor next to the capacitor as shown,
upload_2015-3-1_14-56-32.png
and the results were a ripple factor of 29%.
upload_2015-3-1_14-57-26.png

I've been stuck and can't figure out why the ripple factor went up just by adding a small resistor in series with the capacitor.
 

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crutschow

Joined Mar 14, 2008
27,395
Why would you think the resistor would have no effect?
The load is drawing current from the capacitor during the time it's not being charged from the diode.
This current has to flow through the resistor in series with the capacitor which causes a voltage drop across the resistor.
This voltage drop subtracts from the capacitor output voltage so the capacitor voltage is lower than without the resistor.
If you view the resistor voltage you will see this.
 
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