Lots of noise and hummmmmm.

[sushyoshi]

Hi

I´m new to this kind of DIY stuff.

I have a breadboard that i use to test all this small circuits that i might like. The ones i´ve tryed in my breadboard are:
- Electra Distorcion
- May treble boost
- Vox treble boost
All of them worked fine on the breadboard but only got one problem, lots of HUMMMM. Even at low volume lots of loud humm.

So my questions are:
- Is this normal if i use a breadboard( i´ve read other posts about this telling that breadboards are noisy but i think my noise is a little bit too much).
- I´ve read here that this sometimes happens when the circuit is not proprelly grounded. So how do i ground it? I allways connect the ground to a common one between all grounds and then connect that common to the ground of the input and output jack. I´ve even tried stick the output and input jack sockets into a metal plate to see if the noise would go away without any luck at all.
- Is it the wires that are doing this? Is my breadboard that sucks? Is it my guitar or amp that are not good grounded? Cause when i play guitar directly connected to the amp i only get some noise when i turn the volume up to lots of sound( between medium and max range).

I´d really like to get all the help i could and to know if anyone else is having this kind of trouble and if is there any solution for it.

[R.G.]

It's almost certain that your ground wires are not all connected.

[sushyoshi]

Nop.
I´ve triple checked that every ground wires is connceted to a common ground that connects to both jacks input and output ground.

And when i touch the guitar strings i get less humm but still theres lot of humm and strange noise

[puretube]

*some* larger breadboard`s busses (rails) on the sides have an interruption in the middle...    (?)

[sushyoshi]

No i dont think my breadboard is one of those. Its a really small one. Heres a pic of it (its kind of bad quality sorry  )

[The Tone God]

I think that maybe one of the types of boards with split rails. Why not jumper the rails at the centre just to shut us up ?

Andrew

[R.G.]

Nop.
I´ve triple checked that every ground wires is connceted to a common ground that connects to both jacks input and output ground.
And when i touch the guitar strings i get less humm but still theres lot of humm and strange noise

It's almost certain that your ground wires are not all connected. 

Have you measured that with an ohmmeter? As TG says, just to shut us up?

[sushyoshi]

Ok ive put all ground in the same common rail and still no diference in that. The thing is i can get the effects to work but the noise is too loud.

R.G. : What do you mean with that? Measure te ground for ohms? is the ground supposed to have high resistance? How do i mesure it?

Sorry for such newb questions but this problem is really annyoing.

I´ve read that sometimes the cause of noise is when output is getting some DC voltage . Can this be happening?

Any more suggestions?

[puretube]

No i dont think my breadboard is one of those. Its a really small one. Heres a pic of it (its kind of bad quality sorry  )

exactly where that light reflection in your pic shows up,
that`s where the interruption is...
(in my - what I call "larger" breadboards)


see that little vertical black jumperwire bottom row below on the right breadboard?:


(took me a while to find out, where that connexion was missin` )

[sushyoshi]

puretube: I´ve put the jumper on that and tested to see if there was a common connection on that ground row and it was well connected but with still no luck at all.
Could you guys tell me whats the usually normal values of DC in the transistors legs?
Do you guys think i should try solder everything in a perfboard to cheack if the noise goes away? I have a small box, some perfboard and solder just readdy to start solder. I just wanted to make sure im not getting all that noise even after its all solded.

[R.G.]

It's always frustrating to have noise problems, especially ones that don't go away easily.

What do you mean with that? Measure te ground for ohms?is the ground supposed to have high resistance?

What I mean is that all points marked "ground" on a schematic are conceptually supposed to be connected by zero ohms of resistance. We get hum when one or more of them is left unconnected, or when one section between two parts of the circuit is left open or high resistance.

How do i mesure it?

Take your Digital Multi Meter (DMM) and set it to read resistance (ohms). Connect one probe to the input jack ground terminal. Now take the other probe and touch every single place which has "ground" connected on the schematic. Every single place where the schematic shows "ground" must be very low resistance, less than one ohm. If any one of them has a high resistance you WILL have hum. There are other ways to get hum, but this is the one to check first.

Sorry for such newb questions but this problem is really annyoing.

What is what we call a "non sequiteur", a term borrowed from ancient Latin language meaning "It does not follow". Those are not connected concepts.

First, as a newb, you don't know what you are doing, by definition. That is not something to apologize for. You seem to be trying to learn as quickly as possible, and that is something I respect a great deal. What I find offensive is people who pretend to know more than they do and also people who will not ask when they have a question.

Problems like this are always annoying, perhaps more so to the long-experienced person than to the newb. It would make me crazy if I had a hum problem I could not solve; it's much worse for me than you because I have all of this experience to fall back on.

I´ve read that sometimes the cause of noise is when output is getting some DC voltage . Can this be happening?

It may be, but that is almost never the cause of hum. It makes other kinds of noise.

Test your grounding with the DMM measurement. If you don't have a meter, borrow one or buy one. It's really impossible to do much in electronics without at least this most basic instrument.

[sushyoshi]

i checked to see if there was any resistance in every ground point and only got about 0.7 ohms in every ground connection. You said that it should be lower than 1 ohm so i guess the circuit is well grounded. I dont know if it makes any difference bue whenever a touch any ground point that makes some humm goe away but still there is plenty on humm even in that. I´m using low volume on my amp so there shouldnt be any loud humm.
Anyone got any more sugestions? Just tell me from your experience all sources of humm that you know.

[oldschoolanalog]

Is your workbench in close proximity to fluorescent lighting?
Have you ruled out your power supply as the source of hum?

[sushyoshi]

oldschoolanalog: It isnt close to a fluorescent light. How can i check to see if the power supply is the source of the hum?

I was thinking this: My amp produces a little hum when connecting directly to the guitar and when i touch any guitar chord the hum disappears. If transistors are amplifying my input signal the is it possible that the clean guitar low humm is being amplifyed causing an output loud hum? Its just a theory since that i thought of but i would like to hear more suggestions besides this one.

[Mark Hammer]

It doesn't have to be close to a fluorescent light.  It only has to be in the same room.  My workshop/office has both my computer and CRT monitor AND fluorescent lights.  EVERYTHING I make hums!

[puretube]

it`s handy to have a grounded sheetmetal under the workbench, when playing with "rats nest" circuits...

[Mark Hammer]

Question.

The surface of my desk has enough chips in it that I should probably glue a new sheet of formica on top.  A surplus place near me has nice big sheets of copper shim.  Would it be a good idea to glue a big sheet of that down first (with a handy ground connection off to the side) before gluing a sheet of formica over top?

[johngreene]

Question.

The surface of my desk has enough chips in it that I should probably glue a new sheet of formica on top.  A surplus place near me has nice big sheets of copper shim.  Would it be a good idea to glue a big sheet of that down first (with a handy ground connection off to the side) before gluing a sheet of formica over top?

I don't think there would be any advantage since you are covering it with formica anyway.

Use the sheets of copper shim to make a still instead.

--john

[oldschoolanalog]

How can i check to see if the power supply is the source of the hum?

Brute force filtering. Put a nice big cap, 1000uf should do it, across the power supply,  right where the power supply enters the breadboard, to keep it simple. (+) side of cap to the (+) side of the power supply; (-) side of the cap to the (-) side of the power supply. I'm sure there are more "elegant" ways of doing this, but IMHO this is the quickest way to tell right away. The hum will either be reduced, or not. After trying this, you can take your troubleshooting "to the next level", if necessary. BTW, double check cap orientation. You do not want to put this in backwards.

Use the sheets of copper shim to make a still instead.

--john

Just make sure it's RoHS compliant !

osa

[runmikeyrun]

I have a bad hum at my workbench, it comes from a few sources:

-cheap pickups in my even cheaper guitar

-on breadboards, from all the leads and connectors which amplify even small sources of hum

-the two banks of fluorescent shop lights above my bench, which is a minor source compared to the next one-

-the 100 watt fluorescent light bulb 20 feet away at the bottom of the basement steps.  When i shut it off there is a huge reduction in hum and it's 20 feet away!  I think it has something do to with how the new bulbs meant for a common socket generate the voltage for the bulb.  I even notice some hum go away if i turn off the 3 bulbs in my kitchen fixture which is at the top of the stairs.

-i think the fuse box being right above the bench also has something to do with it.

So check your grounds but also check your environment.  My old house used to be about 1/4 mile from a 50,000 watt AM radio disney transmitter tower.  I had every frickin kids song memorized because they played through my circuit whenever it was plugged into the amp and not inside a box. countless hours playing while substituting diodes or trannies was torture.  Boxed it up and no more radio disney.

Also check your cables for bad connections, amp ground, guitar ground, and outlet ground.  Could be one of a lot of grounds gone bad.  If it doesn't do it with any other pedal then it's the pedal.  If it does it with other pedals you've got an envioronmental or one of the aforementioned problems.  Hums can be very irritating and hard to track down.  Make sure you're not by a computer, electrical box, fuse panel, anything.