what capacitors to use around 7805 and PICs

[pkshima]

LM7805 datasheet says 0.1 and 0.33 uf caps but almost all circuits found online use other values. not just that, some use polarized some use ceramics.

Same for the cap thats supposed to be put as close as possible to PIC on its power supply. what type and value it must be ?

My circuits work fine but just cant make sense whats the way to know the right type and value to use.

 

[Nigel Goodwin]

There is no 'right' type and value, they are there to do a specific job and a wide range of values (and types) do that perfectly well.

 

[pkshima]

Thanks Nigel.
I read today that electrolytic caps are good to be put close to the power supply and ceramics close to the device.
("http://www.sparkfun.com/commerce/tutorial_info.php?tutorials_id=57")

Then I looked at your tutorials again and found electrolytic caps on both the 78L05 and the PICs. So got confused again.

Is it that since all your boards are too small for distance to make much difference ?

 

[Nigel Goodwin]

Thanks Nigel.
I read today that electrolytic caps are good to be put close to the power supply and ceramics close to the device.
("http://www.sparkfun.com/commerce/tutorial_info.php?tutorials_id=57")

Then I looked at your tutorials again and found electrolytic caps on both the 78L05 and the PICs. So got confused again.

Is it that since all your boards are too small for distance to make much difference ?

No, it's because it makes no difference - it's really not at all critical.

 

[pkshima]

Ok great, I will also go with 1uF then.
will use a 100uF on the power supply of the motor controller.
thanks again.