[aprssig] LM7805 and caps

Andrew Rich vk4tec at people.net.au
Sun Aug 26 15:36:50 CDT 2007

Can someone explain to me why this is so:

I have been building some projects now that use LM7805 voltage regulators.

This is now the second time I have had issues with a PIC chip not running.

It is only when I add caps to the input and the output that it settles down.

Looking on the CRO, the DC looked noisy.

I thought that the caps where there to trap AC.

Do caps on an LM7805 player a larger role ? Is there something inside the
reg that needs external C ?


Andrew Rich VK4TEC
vk4tec at people.net.au

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