# URGENT HELP RQ'D!!!!!!!!!

Discussion in 'Homework Help' started by Matt_B, Dec 5, 2008.

1. ### Matt_B Thread Starter New Member

Dec 5, 2008
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0
I am currently a 2nd year HNC electronics student and am investigating unregulated non-linear power supplies which convert 230v AC I/P supply into 10v D.C supply by means of a transformer, bridge rectifier, reservior capactior and a low pass filter (smoothing circuit), as per the below diagram, except with a resistor in place of the inductor and a Load Resistor placed on the D.C terminals

Under simulation on a software package, changing the Load resistor in decade steps from 1Ω to 10KΩ gave the following results:

1 Ω................................ 99.38 mV.................. 9.38 mA .............60 mV
10 Ω ..............................920.5 mV ..................92.05 mA ...........440 mV
100 Ω .............................5.472 V ....................54.72 mA........... 460 mV
1000 Ω ..........................11.39 V ......................11.4 mA ............100 mV
10000 Ω......................... 12.57 V ....................1.269 mA ............10.8 mV

Now i understand what these results are telling me although i cannot understand or explain why the ripple (A.C component within the D.C supply) increases than decreases again.

Apr 5, 2008
15,801
2,387
Hello,

What value has the resistor, that is in place of the inductor?
This is of influence of the output voltage.

Greetings,
Bertus

3. ### jpanhalt AAC Fanatic!

Jan 18, 2008
5,699
909
Perhaps you should consider the ripple as a percentage of the load voltage. Your load current follows the same pattern. Thus, the left side (including the resistor mentioned by Bertus) is current limiting.

John

4. ### Matt_B Thread Starter New Member

Dec 5, 2008
2
0
Thank you both for your prompt replies.

The values are as follows:

Reservior capacitor: 100μF

Filter: 100Ω and 100μF

These figures stay constant and the only value that changes is the load resistor.

Thanks again.