Apple Mac power supply

[meddyliol]

I have an Apple power supply which gives out around 16-18V. I want to use it and reduce the voltage to 9V regulated. Would an LM7805 do the job (with a few extra bits of course) or would another regulator be better. Another idea might be to have a choice of either 12V or 9V. If anyone has a circuit it would be helpful .

Any suggestions would be appreciated

Thanks

Brian

 

[heydonms]

The 7805 is a 5V reg. A 7809 might be suitable but you don't provide much detail. Do you need to supply 50mA or 5A? Do you need low ripple? Is heat an issue? Is efficiency important?

Personally my first choice would be a switcher, they are cheap enough now to compete with linear regs so unless you are doing audio work there aren't many reasons to go for a 78xx.

 

[meddyliol]

Thanks for your prompt reply. I just need a general purpose PS with 9-12V at about 1A. What type of switching regulator would do?

I just found one of these, would it do?

**broken link removed**

 

[heydonms]

Yep. They say you need heatsinking if you go over 2A, but I would keep an eye on the temps once you start pulling about 1A just to be on the safe side.

 

[meddyliol]

OK, thanks for that. I have decided to go for this one:
**broken link removed**

Cheers

Brian