Help building a smokey amp

[ahjm]

Hi all, I recently decided to give building an amp a go, starting with the simplest amp on the planet the smokey. But as I know nothing about electronics I'm a bit confused about one part of it. I'll attach the schematics I'm working with

Basically I don't know how to connect the 3 lugs of the stereo input jack onto the circuit board. I know one goes to the Lm386 and one goes to ground, but I don't know where to connect the last lug. Do I just use a mono input jack?

Also, a very basic question but how to go about grounding in a design like this? Do you just solder all the ground wires together?

[JHow]

You only need a mono jack for this circuit. I would just get a mono jack, they're pretty inexpensive. If you want to try and make stereo work, think about it this way: the signal from the guitar will be going to the tip of the plug, so use the appropriate lug to take the signal off the tip.

Re: grounding, depending on how you set this up (small perf board, small "universal" pcb) you can connect the grounds in a number of ways.

I would suggest you get a 8-pin socket (save you from burning your chip) and a board like below (which oddly seems to be out of stock?!):

Dual General-Purpose IC PC Board - RadioShack.com

You can use the extra holes to connect the external components and small jumper wires.

Make sure the battery negative lead is attached to the circuit grounds, which might not have been obvious in the schematic.

If you want a little bit more refined LM386 take a look here:

Little Gems

Runoffgroove has a lot of good info, and there are links that can send you to pcb layouts and the like, vastly improving your initial chances of success.