Wiring experiment, bit of a question ;)

[Imp]

hey guys, i fitted a single humbucker into a LP copy, experimenting with splitting options..

basically, i got a les paul pickup selector (just the 3 contacts, bridge/out/neck) and attached the wires like this

Red/white - Output wire - Black

with green/ground attached to earth. now, when the switch selects the black wire, full humbucker mode. with the red/white selected, single coil.

however the middle position (red/white AND black selected) sounds different. does this selection put the coils in parallel?

tom

 

[Artie]

Re: Wiring experiment, bit of a question

What you're hearing is the slight affect of having the unused coil shorted or open. A coil acts as an AC generator. By having it shorted, its trying to generate voltage back into itself. It does have some affect on the field around the coils.

This is how an electrical motor brake works. By shorting the wires of an electric motor, it brings itself to a stop faster.

 

[Breogan]

Re: Wiring experiment, bit of a question

If I understood you correctly you don't have exactly what you think. If we name the positions starting on the black I think you have:

1) Full humbucking (as you stated): since green it's solded to ground, white and red are solded together and black it's solded to the output this a standar humbucker config.
2) Single coil (screw coil): In this selection the black, the white and the red conectors are joined together. Since white and black are sides of the same coil, and they are joined together, this coil can be "seen" as it doesn't exist (it's call a shortcut). So it only remains the red conector with the green on the ground, which it's a "split" humbucker or a single coil.
3) Parallel configuration with a broken ground: Now white and red are conected to the output, green it's conected to ground and black it isn't conected to anything. You have one coil, red and green, working normaly. The other coil, black and white, working with the white conected to the output and black without being conected to anything. When a pickup has a "disconected" ground usually hums a lot. Do you experience this noise?

Hope this helps...

 

[Imp]

Re: Wiring experiment, bit of a question

it does have a bit of buzz, it sounds like you're right breogan hehe

i was just wondering what i had created, i've not tried to wire in parallel before..

cheers guys :burnout:

tom

 

[Artie]

Re: Wiring experiment, bit of a question

The other coil, black and white, working with the white conected to the output and black without being conected to anything. When a pickup has a "disconected" ground usually hums a lot. Do you experience this noise?

Just wanted to clarify this - no wire on a pickup is "ground", until you connect it to ground. A coil that has one wire disconnected will produce no sound, or noise, or anything. It can't, because its not a complete circuit.

If one coil is disconnected, its just a "split".

 

[BlueGuitar]

Re: Wiring experiment, bit of a question

... A coil that has one wire disconnected will produce no sound, or noise, or anything. It can't, because its not a complete circuit.

I hate to disagree with you since you are always so helpful here, but try this experiment: plug in one end of a guitar cable into the input jack of your guitar amp and touch the tip of the other plug with your thumb (without touching the grounded barrel of the plug). Turn your amp way down before doing this because you will get a loud hum even though the circuit is not completed.

With a guitar plugged into an amp, if one end of a pickup coil is connected to the hot output and the other end of the coil is connected to nothing, the guitar will be susceptible to RF noise, etc. (Try turning on the TV or a light dimmer to add to the RF noise).

Now if the guitar is shielded and the pickup has a metal cover, that will keep the guitar quieter during this experiment. Like the Fender Custom Shop 4 way switch for the tele- the neck pickup is always connected to the hot signal lead but the ground is interrupted in the bridge only position. If not for the metal cover that position would be noticeably noisier because the unterminated signal lead going to it.

In any case, to keep the noise down in wiring harnesses I try to avoid unterminated signal leads whenever possible... although sometimes it isn't. Like a coil split switch which connects the HOT to the white and red wires as well as the black wire on a SD pickup. (Not exactly unterminated but there is HOT connected to both ends of the Black and white coil.)

Perhaps someone else can explain the phenomenon better... why an unterminated circuit can create noise (and a lot of it!)

--Thanks!

 

[Artie]

Re: Wiring experiment, bit of a question

I hate to disagree with you since you are always so helpful here, . . .

Thanks . . . and you're absolutely right. Shortly after I posted that, my mistake occured to me.
An unterminated wire, at the end of a coil, makes a great antenna.

It would pull in RF and 60 cycle hum like an old Victrola.

My turn to say . . . my bad! :smack:

Artie

 

[BlueGuitar]

Re: Wiring experiment, bit of a question

Artie:

Awhile back you mentioned having an oscilloscope at work... so what is your "day job", if you don't mind telling us? (I'm an HVAC service tech who loves to design control circuits with relays. It's great not having to worry about the audio and noise issues involved with guitars and amps! :burnout: )

Thanks again for all of your contributions here!

 

[Artie]

Re: Wiring experiment, bit of a question

Hey Steve; I work in a Navy Calibration lab, so I'm surrounded with literally millions of dollars worth of the worlds best measurement standards. Its kinda cool when I can measure my Cool Rails to 10,369.845201662 ohms. :laugh2:

Prior to this I worked in an Air Force cal lab, and I've always been involved in electronics - from guidance systems to pro-audio. I used to do sound work, and even a little time in a very small recording studio. Mostly commercials and stuff.

My current main specialty is infrared and laser guidance systems. I calibrate the console that calibrates the FLIR (Forward Looking InfraRed) pods on aircraft. A lot of what I do is on aircraft carriers and at remote sites, so I get to travel alot.

For fun . . . I try to figure out creative ways to wire up guitars.
Sometimes they work . . . sometimes they don't. :laugh2:

btw - messing with relays and AND/OR, etc., logic gates is one of my favorite "relaxing" techniques.

 

[BlueGuitar]

Re: Wiring experiment, bit of a question

Hey Steve; I work in a Navy Calibration lab, so I'm surrounded with literally millions of dollars worth of the worlds best measurement standards...

... and if you told me any more than that, you'd have to kill me! :smack:

--Thanks for filling us in!

 

[Imp]

Re: Wiring experiment, bit of a question

whoa, cool job! :burnout: