Need Help In making power supply! :(

[nobody0725]

Please I really need help here, I don't know where to start, I'm just a college student.

I'm given the facts that:
1. Input AC voltage is 220v (RMS) at 60Hz.
2. Output Dc voltage (unregulated-no regulator)
- 9v, +5%, -5%
3. Maximum Ripple factor 3%
4. Maximum Load Current 250mA

Please help me, As soon as possible.

[star882]

12v wall wart (at least 300mA rating, preferably 500mA or above) and a 7809 regulator.

[Redshift187]

Do you mean you aren't allowed to use a regulator?

Getting 10% regulation (+/- 5%) on a power supply as small as 250mA is not likely without a regulator. The bigger the transformer, the lower the regulation, meaning less variation between idle and load output voltage. If you are able to use a regulator, what star882 said is correct.

[AndrewT]

if the mains varies by +-6% then one has no hope of meeting +-5% voltage tolerance.

[keantoken]

It looks like you need to check back with your teacher and make sure your requirements are correct.

- keantoken

[DougL]

Originally Posted by nobody0725

Please I really need help here, I don't know where to start, I'm just a college student.

I'm given the facts that:
1. Input AC voltage is 220v (RMS) at 60Hz.
2. Output Dc voltage (unregulated-no regulator)
- 9v, +5%, -5%
3. Maximum Ripple factor 3%
4. Maximum Load Current 250mA

Please help me, As soon as possible.

The way I read it is you need to design a 5V ps with 150 mv of ripple, and a 9V ps with 270 mV ripple.

Download PSUD2, and give it a try. There are a couple of articles on the web on how to use it.

HTH

Doug

[Gordy]

Originally Posted by nobody0725

Please I really need help here, I don't know where to start, I'm just a college student.

I'm given the facts that:
1. Input AC voltage is 220v (RMS) at 60Hz.
2. Output Dc voltage (unregulated-no regulator)
- 9v, +5%, -5%
3. Maximum Ripple factor 3%
4. Maximum Load Current 250mA

Please help me, As soon as possible.

This is your first post, right?
You joined the forum for this, right?
You're not actually going to use this, right?
You just want to USE US TO DO YOUR HOMEWORK, right?
And you want us to do it for you 'as soon as possible' so you can hand it in on time, right?
You want to suck on our good will to compensate for your pathetic lazyness, right?
And you think that we have nothing better to do, right?

Learn it the normal way, and use the example in the text book just as your tutor showed you.



(...said Gordy, not known for sitting on fences).

[MJL21193]

Originally Posted by Gordy

(...said Gordy, not known for sitting on fences).

Bravo!

[keantoken]

I would state it more politely, but I do agree that someone going into EE should listen to the professor speaking... Engineering is not for the fainthearted.

- keantoken

[EC8010]

My attention has been drawn to this thread. Please don't let that happen again.