Schematic question

[DeusM]

Hey guys. So, I already have all the things I need to star building my first "real" pedal, but I have a couple of questions about the schematics. My questions are: 1) The 9V symbol, is it the positive side? Or does it mean both sides of the battery goes there? If so, is it positive to the right and negative to the left?
2) If I choose to use a led that's not red. How do I calculate the resistor for it? And despite the color, how do I calculate the resistor for the LED?
3) SW Is the switch?

Hope you guys can help me like always 

[EBK]

1. Positive.
2. To taste. Really depends on how bright you want it -- 1k to 10k range is a good starting place.  The current through the LED will be (9-Vf)/R, where Vf is the forward voltage of the LED (measured or from specsheet) and R is the resistor value.  Most LEDs you will likely see will tolerate up to 20mA, but would be happier with 15mA or under.  Try to go much lower though, currentwise, or the LED will be annoyingly bright in many cases.
3. Yes.

[rutabaga bob]

Hey!  The 9V symbol is positive (you can see the little + sign in front of it.  Positive all along that top line.

You can start with a 1k resistor...it all depends on how bright the LED is...more resistance will dim the light.  Many folks use 4.7k with a bright LED.

SW is switch.

[DeusM]

Hey!  The 9V symbol is positive (you can see the little + sign in front of it. 

Oh you are right!! I feel so dumb! I need to star wearing my glasses more often.
So I feel kinda dumb asking this but the - side goes to ground right? It's been a couple of months since I made my first prototype so I forgot a couple of things.

[EBK]

Yes, negative side to ground.
It's ok if you feel dumb, as long as it doesn't stop you from asking the questions that are necessary to your continued pedal building .

[DeusM]

Yes, negative side to ground.
It's ok if you feel dumb, as long as it doesn't stop you from asking the questions that are necessary to your continued pedal building .

Hehe. You guys are very nice to me. It's great to see so many people here willing to help guys like me who are just starting.
I think I'll have the pedal finished in a couple of weeks, maybe a month. I'll make a post when I finish so I can show you guys all theprocesss. It's my first pedal so It's a big thing for me 

[GibsonGM]

Hey!  The 9V symbol is positive (you can see the little + sign in front of it. 

Oh you are right!! I feel so dumb! I need to star wearing my glasses more often.
So I feel kinda dumb asking this but the - side goes to ground right? It's been a couple of months since I made my first prototype so I forgot a couple of things.

Don't feel dumb, Deus! We all have to start somewhere!   It is a good intro question - not all circuits use what is called "negative ground".   This one does...and most do, but not all....so we can call that " - "    GROUND.     

If you weren't sure and did it backwards, you could burn up the transistors.   Now you know   


<<Side lesson:  I know you are going to play with it, so.....LEDs are weird...they don't have very much resistance in one direction when they are "on".  The band is the cathode, and goes to "minus", or GROUND in our circuit.    The other side, the + side, is the anode.   

If you have the cathode more negative than anode, and voltage is above the minimum req'd for the LED ("Vf or forward voltage), it will turn on. 

Because of this lack of resistance, they will 'take all the power you can give them' and will destroy themselves if you don't have a resistor along with them.  The resistor can go before or after the LED, by the way         For 9v circuits, you are usually OK if you use a resistor of AT LEAST 470 ohms, and you can always go higher to make it dimmer.  Just always have that minimum resistance there!   The others are 100% correct, you'll want higher, like 1k or more, just putting that minimum out there.   New high brightness ones will blind you, often even with a 1k. 

When I started out I just DID NOT GET IT, that a part could be given the correct voltage but destroy itself!  And that's why.  Ohm's law gives us the answer (about 19mA for 9V/470 ohms), you will see what I'm saying later when you get into it.   

Good luck   

[amptramp]

The switch in this schematic doesn't do much - it simply turns the LED on and off.  The switching is usually set up so that another pin on the input jack goes to ground when the plug is connected and the battery is connected to that pin.  (You could also make it the output pin but input is the more normal connection.)

[GibsonGM]

The switch in this schematic doesn't do much - it simply turns the LED on and off.  The switching is usually set up so that another pin on the input jack goes to ground when the plug is connected and the battery is connected to that pin.  (You could also make it the output pin but input is the more normal connection.)

I didn't want to overload the poor guy 

Take out the switch, run that side of the LED right to ground.    Up where the + 9V comes in...put the switch there.   Then, the LED will only light when the circuit is active, and won't lie to you about it being on! 

One tip - don't make a switch or anything too permanent, just tack it in there to operate.  Or leave it out, incl. the LED.   Later, you'll probably want to, as Amptramp is hinting at, place your Muff in an enclosure and add a stomp switch, plus that trick where when you plug a cord into the input jack, the thing turns "on". 

But early on, to assure that it works, I totally think you should build it (breadboard or perf, whatever), and tack jacks on, maybe just jumpers to the battery...see if it works!    Then deal with switching, so you know that's where your mistake is if it does not work!   K.I.S.S. - keep it simple, stupid!  Works wonders...

[thermionix]

Well the LED switch is correct if you consider that they just omitted the audio bypass switching from that schematic altogether.  And the jacks, and negative end of the battery.  A few component values too.

[Jdansti]

Well the LED switch is correct if you consider that they just omitted the audio bypass switching from that schematic altogether.  And the jacks, and negative end of the battery.  A few component values too.

What he said. The LED and bypass switch are normally not shown on schematics. This one is a fluke. It's normally assumed that the builder will incorporate his own scheme for bypass switching and the LED indicator. For now, omit the LED, resistor and ground connection on the upper left portion of the schematic and get the circuit working without worrying about these things. When you have it on a board and you're ready to box it, if you need help with bypass switching and the LED, ask and you'll get many options from the community.

[DeusM]

For now, omit the LED, resistor and ground connection on the upper left portion of the schematic and get the circuit working without worrying about these things.

You are right. I shloud let the switching for later. I'be been reading about 3pdt and true by pass and milenium by pass so I hope I can make it work