Topic: Help LM7805 Circuit

[bagtagsell]

In anticipation of a MT, I thought I would build a voltage regulator.  But its not working. 
Q: Did I wire the circuit right? (see picture)

Q: On page 1 on JB3 power2 thread, leegedy shows a schematic thats what I was trying to follow.  Can anyone explain this very slowly.

[bagtagsell]

picture coming soon.

[Brian Skalinder]

Pos (+) wire from battery to 7805 input pin.
Pos (+) wire from 7805 output pin to device's power plug.
Neg (-) wire from battery to ground (GND) pin, and from ground (GND) pin to device's power plug.

[bagtagsell]

I think I messed up somewhere.

is this right?

where do the other caps and resistors go?

[Chuck]

http://www.iguanalabs.com/7805kit.htm

[bagtagsell]

Thanks for the link chuck. 

Where should I put the resistors?

[Chuck]

Thanks for the link chuck. 

Where should I put the resistors?

Let me get my data books out.
If I remember right, you can set up a voltage divider with a couple resistors...
It's been a while... I'll get back to you.

[Chuck]

Here you go:

[Chuck]

I must've been thinking about a variable voltage regulator. The capacitors are used to filter and reduce ripple.

[recordista]

Check out the LM2940, which will work with lower battery pack voltages than the 7805 will.

[bagtagsell]

Update...

I removed all resistors.  I have one capacitor linking pins 2 and 3.

I have the pin of the battery going to pin 1 of the regulator

I have the sleeve of the battery going to pin 2

I have the pin of the output going to pin 3 on the regulator

I have the sleeve of the output going to pin 2 on the regulator

and I got nothing.

As I understand the capacitor is helping stablize the power?  I think if I removed it things might work, but I don't know.  If this is the right wiring is my regulator bad?