Here's a wiring diagram, where's the hum coming from!

lightandmind · **Joined:** Mon Jan 16, 2012 6:59 pm **Posts:** 11

Here is a very crude wiring diagram. I'm getting hum when the AC adapter is plugged in, but it's silent with battery use. This is my first build! It's an SHO copy, (Mosfet circuit), with B.Y.O.C. parts & enclosure, I had to figure out the wiring myself and I think I'm missing something, can you tell me what I'm doing wrong? Any other changes you would make to the wiring? Thanks!!!

GrindCustoms · **Posted:** Tue Feb 28, 2012 3:04 am

I see that the circuit input on 3pdt is not grounded when in bypass. Link that lug to the remaining LED ground lug.

Hope it helps! :wink:

Stephen · **Posted:** Tue Feb 28, 2012 4:59 am

If the circuit is silent with a battery and noisy with a power supply it's the PS that is the problem. It's most likely a poorly filtered un-regulated wall wart type PS and should not be used to power audio circuitry.

lightandmind · **Joined:** Mon Jan 16, 2012 6:59 pm **Posts:** 11

Quote:

I see that the circuit input on 3pdt is not grounded when in bypass. Link that lug to the remaining LED ground lug.

By running a jumper from the circuit input on the 3pdt to the unused section in the lower right-hand corner? But that's positive, right?

lightandmind · **Joined:** Mon Jan 16, 2012 6:59 pm **Posts:** 11

Quote:

If the circuit is silent with a battery and noisy with a power supply it's the PS that is the problem. It's most likely a poorly filtered un-regulated wall wart type PS and should not be used to power audio circuitry.

i think you nailed it

TNblueshawk · **Posted:** Tue Feb 28, 2012 6:56 am

Stephen wrote:

If the circuit is silent with a battery and noisy with a power supply it's the PS that is the problem. It's most likely a poorly filtered un-regulated wall wart type PS and should not be used to power audio circuitry.

Stephen, why would you not ground the switch too? Just looking to understand.

GrindCustoms · **Posted:** Tue Feb 28, 2012 7:00 am

TNblueshawk wrote:

Stephen wrote:

If the circuit is silent with a battery and noisy with a power supply it's the PS that is the problem. It's most likely a poorly filtered un-regulated wall wart type PS and should not be used to power audio circuitry.

Stephen, why would you not ground the switch too? Just looking to understand.

I'd like to know too.... :roll:

Stephen · **Posted:** Tue Feb 28, 2012 7:05 am

Definitely ground the stomp switch. This provides a path to ground for the LED. It also provides a connection to ground for the input of the circuit which helps to prevent turn ON pops. Whether the ground connection is there or not wouldn't have anything to do with the power supply noise.

I do not recommend using the switch wiring shown in the diagram above. It does not short the circuit's input to ground in bypass mode and is very likely to cause a pop when you turn the pedal ON & OFF. I recommend this method of wiring the stomp switch which does short the circuit input to ground.

GrindCustoms · **Posted:** Tue Feb 28, 2012 7:16 am

And here's one going with your drawing!

SUPER SIZE PICS!! :lol:

sjaustin · **Posted:** Tue Feb 28, 2012 7:24 am

Hijack: Grind, what software are you using for your layout?

GrindCustoms · **Posted:** Tue Feb 28, 2012 7:28 am

sjaustin wrote:

Hijack: Grind, what software are you using for your layout?

DIYLC3, DoItYourselfLayoutCreator3.

Pretty fun to use!

I don't have any download links, it's free, but the downloads where'nt working with my pc....so i got the zipfile from a member.

If i remember well, search for stormsoftware.... :roll:

lightandmind · **Joined:** Mon Jan 16, 2012 6:59 pm **Posts:** 11

You guys are freaking awwwwwweeeeesome.

lightandmind · **Joined:** Mon Jan 16, 2012 6:59 pm **Posts:** 11

Hey, the LED resistor is rated 1/2-watt, 5% tolerance, Max Working Voltage 350V, (as seen here: http://www.radioshack.com/product/index.jsp?productId=2062318#), should I be using a different one? The specs for the LED itself are FW current: 20mA; FW supply: 3.2 (typical), 3.8V (maximum), (as seen here: http://www.radioshack.com/product/index.jsp?productId=3107633), would you recommend a different one? Thank you, and sorry for my newbiness

TNblueshawk · **Posted:** Fri Mar 02, 2012 10:46 pm

You want 1/4w and not 1/2w. You can use the 1/2w but it is larger and may not fit well depending on the board. You need something more than 270ohms too. Maybe 4.7k is popular but you could go up to 10k.

That LED will work. It will be bright.

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Here's a wiring diagram, where's the hum coming from!

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