PIC 1684A Power Supply

[Dudekiller]

I'm getting ready to build my own PIC circuit but I have a couple of questions about the power supply circuit. I'm planning on using this http://www.pyroelectro.com/tutorials/pic_breadboard/power.html diagram, but I was thinking about using a 10uf capacitor. Is this a good idea? Can anyone explain to me the benefits or the consequences of having a higher powered capacitor?

[Qubix]

While the 7805 will regulate the power down to a nice 5v. The job of the capacitor is to smooth out noise in the power supply. In general the value of the capacitor will determine the frequency of the noise it will smooth out. For a general power supply 10uf should be fine or you could use both 10uf and 1uf if you like.

If you look at the spark tutorial for setting up a power supply they use two different values before and after the regulator (100uf and 10uf).
http://www.sparkfun.com/commerce/tutorial_info.php?tutorials_id=57

Also look at the data sheet for your pic and see what value it suggests.

Hope this helps

David

[superchiku]

capacitor also provides extra charge in case of a sudden need of current...so use a nice and big 220 micro farad capacitor..

[Soeren]

Hi,

On the output, use a 10µF solid tantalum cap or a 22µF standard wet electrolyte.
On the input, use 10µF to 47µF, considering the power source is a 9V PP3.

However, it is not a very good circuit, since the 9V battery is considered empty at 5.4V and the 7805 need 8V to 8.5V in to provide a stable 5V out, so you'll never get more than a small part of the power in the battery.
A possible solution is to use a low drop regulator, then you can use all of the battery up.

Apart from that, a linear regulator is very wastefull and considering the small capacity of a PP3, I wouldn't bother at all - just power it by AA's or AAA's and forget about the regulator.