Little Gem / Ruby amp - IC's and resistor ratings

[Floyd]

Hello there! Awesome site.

This is my first post here. I hope this is the right place for this.

I'm going to be building my first amps when the rest of my components get her via mail.

I've rewired my strat and breadboarded some stuff before, but my actual knowledge of electronics in general is pretty limited so far, so please keep that in mind.

I'm going to be using a LM386N-3 in my Little Gem and Ruby amps. According to wiki the LM386N-3 has a minimum output power of 500mW and a typical output power of 700mW.

Keeping this in mind should I use 1/4 watt resistors or 1/2 watt resistors? Does the output power of the IC even dictate the watt rating of the resistors?

I've searched for hours online and still haven't found an answer to this seemingly simple question. I found 2 parts lists that call for 1/2 watt resistors on the little gem. Then I found some guy on another board who said 1/4 watt is fine. Then I read the GGG PDF layout and parts list for the Ruby and it says 1/4 watt resistors. Considering the Ruby is an improved version of the little gem I would assume 1/4 is fine, but I'm still not sure.

I'm holding off on my final components purchase until I can get some clear info on this, so I can add 1/2 watt resistors to my order if necessary.


Also are there any additional safety precautions I should take when working with an IC or these amps in general? Any power storage/discharge, shock hazards, or overheating concerns?
I figure that these are low enough power amps that they are fairly safe to work on, but I would rather not fry my noob ass by doing something blatantly stupid


Thanks,

Floyd

[waltk]

Hi - Welcome.

Yep, this is the right place.

1/4 watt resistors are fine for just about anything you would find here.
As long as you stick with a 9-volt battery power source, there's not much you can do to hurt yourself.
You probably shouldn't use your tongue as a circuit probe  , but other than that...

If you were to short the battery terminals together (directly or inadvertently in the circuit), something would get warm/hot - more of a learning experience than a real danger.
Soldering irons are hot.
Using big power tools to drill enclosures can be hazardous.  Be sure to clamp your work down and be familiar with your tools.  Protect your eyes.

[Floyd]

Thanks for the quick response

I'll give the 1/4 watt resistors a whirl then.


"If you were to short the battery terminals together (directly or inadvertently in the circuit), something would get warm/hot - more of a learning experience than a real danger."

Haha yeah I did that on my first breadboarding project. That was one hot battery


One last stupid question:

When I was breadboarding a fuzz face recently I had it all up and running and was playing my guitar through it to test it out on my amp.

I was switching components out by hand while playing to see what it did to the tone. Is it a bad idea to do this when breadboarding a fuzz and other pedal types? Should I actually unplug from my amp, disconnect my battery, change a component, reconnect my battery, and plug back into the amp every time? Or is this just plain overkill?

I'm not asking what the textbook "according to blah blah blah" response is on this one. I'd like a real life response if possible. What do YOU guys personally do?


Thank you all again very much for taking the time to help me out. It is very much appreciated.

[waltk]

I was switching components out by hand while playing to see what it did to the tone. Is it a bad idea to do this when breadboarding a fuzz and other pedal types?

This sort of swapping/trial-and-error is the purpose of breadboarding.  I usually disconnect the battery before swapping components (a switch in your power connection is good for this).  Most of the time nothing bad would happen, but if you inadvertently brush the wrong leads together while doing it, you could fry a sensitive component.  Unplugging and disconnecting everything is overkill - IMHO.  I usually take a little more care the first time I power up something new.  I monitor the current draw and keep a finger on the power switch just in case I miswired something.