Star Ground Disc Thingie - wazzit called??

[WBear2GCR]

Ok, for star grounding. Usually a copper disc with holes in it for wires to solder to. Also implemented as multiple solder lugs on a screw... the question is *what is it actually called*? And who sells it??

Regular searches yield nothing, tried lots of variants of terms.

Anyone know if these are commercially made??

                    _-_-bear

[W7TFO]

Metal Singer sewing machine bobbin.

Use a machine screw through a short metal spacer, nut & lockwasher on other side.  The plating takes solder beautifully.

I have seen that exact item in milspec gear, never in raw copper.

73DG

[KM1H]

Try DXE but it will likely be overpriced. Look for grounding plate as it is usually used for radials.

Carl

[KA0HCP]

MFJ, DX Engineering

Copper plated 'plumber's tape' is a heckuva lot cheaper.  Another option is kitchen sink strainers with all the holes in them.

[W7TFO]

Methinks you guys are really off-base .

Here is what the boy is talking about:

#1...Original Rockwell-Collins circuitry.

#2...Me holding said bobbin adjacent.

#3...Object on bench, homebrew.

Jeez.

73DG

[W3RSW]

The Collins lash-up might  look pretty, but All those long cabled runs adjacent to each other carrying GKW and swirly attachments kind of negate a point to point star ground don't you think?

I really like the bobbin idea.

[KM1H]

Methinks you guys are really off-base

A clearer description would have helped; OTOH I dont believe Ive ever seen one of those thingamabobbies

Carl

[WBear2GCR]

Yes, that is the whatchamacallit!

Now the question is what is it properly called, and who ever made it commercially?

Or, who makes such and item today?

I made my own out of some heavy copper flashing years back, that and a hand punch (like a single paper punch but for sheet metal - they still sell them). I used it to help stabilize a commercial copy of the Futterman OTL hifi amplifier (which doubles as a free running RF oscillator).

                      _-_-bear

[KB2WIG]

Its really a round tuit.


klc

[W7TFO]

What's wrong with the bobbin idea?

I swear the factory thing was exactly the same, with two levels of grounds.

Under $.75 per, too.

73DG

[WBear2GCR]

nothing at all wrong with it.
or you can use solder lugs on a screw
or you can make ur own, as I have...

but the question de jour is what is its proper nomenclature??

[VA3AEX]

In building guitar amps, one my of amp 'elmers' swore that star grounds didn't work, and was one of the worst ideas to be impemented when building amps.  When he saw an amp modified to a star ground, he'd rip it out and re-implement the original grounding scheme, typically a wire buss.  I didn't notice an audio difference, but the wire bus did clean alot of wire that was going to the star ground.

[WBear2GCR]

Well what they do is to take current off a single buss, and make each part or section that goes to the star ground have its own path. In the case where there is sufficient current causing Vdrop and/or sufficient ripple, it will be imposed on the other sections along the buss carrying the "ground".

You can think of it as a B+ supply rail, one case everything comes off a single long wire, high current draw and low, the other equivalent to the star ground, each section gets its own wire directly (and preferably with it's own decoupling cap in that case).

Most situations don't require a star ground. But it does tend to make circuits more stable at HF in some situations. Often quieter too, when that matters. Like in a mic preamp or similar case.

                 _-_-

[W3RSW]

1 ea., plate, grounding, double concentric, 1 in., 0. 250 central column, plated. $0.50 each.

[N4LTA]

Sound like the guitar amp Phools. The only right way was the way they used to do it - and those hummed like heck.

Star grounding is the only way to build a guitar amp (unless you are a guru). I have experimented MANY times and tested and tested. Every amp that I build now is quiet and that used to sure as heck not be true.

If you don't do it properly, then it won't work  - You have to isolate the input jacks from the chassis ect.

Pat
N4LTA

[KA0HCP]

When everyone else in electronics works to have the shortest possible ground paths, e.g. using PCB planes or chassis grounds, why are guitar amps so special that a star ground is the best solution?

[kb3ouk]

Probably because having multiple grounding points inside an amplifier creates ground loops, and since guitar amps have a pretty high amount of gain, they're really gonna hum and buzz.

[W3RSW]

Which is what they want... Flangers, warblers, gross IM, Gross harmonic distortion and everything as non-linear as possible. And if that's not enough, flip the "tube sound" switch.

So the real laugh is that in the guitar world, "Linyear" is the exact opposite from what they want, ...or am I confusing that with the 11 meter world?  

Drive those 6L6's baby!

Anyway, back to subject.  Biggest concern is keeping power runs off the signal runs in the grounding loop world.  Whole traces have been vaporized from trace design errors.  Well, would you believe heated and popped beyond recognition?

First time I ran into isolated audio input jacks was in the Dynaco amp kit, then in the Citation II amp kit if I remember correctly.

[WBear2GCR]

1 ea., plate, grounding, double concentric, 1 in., 0. 250 central column, plated. $0.50 each.

No link...

[KK4YY]

http://www.sewingpartsonline.com/bobbins-class-15-metal-10-pack.aspx

[KA0HCP]

So the real laugh is that in the guitar world, "Linyear" is the exact opposite from what they want,

Point well taken!   

[K1JJ]

.

[N4LTA]

They certainly don't want linear - but they sure as hell don't want HUM - especially in a recording studio.

The same goes for a high fidelity amp - tube or solid state.

N4LTA

[W3RSW]

Bear,
No link 'cause I made it up using quasi mil. and commercial purchasing dept. / utility co. Material catalog nomenclature.

Only difference is that in our materials catalog an "x" was placed in front of an item number (missing in my listing) to indicate it was carried as a stock item in the numerous district and central warehouses.

In most companies re-organized after WWII, everything was copied from the military, from the whole org. Chart of line and staff functions, operation divisions, districts and so forth right down to materials purchasing and procurement.

As you can imagine in the gas co. Many catalog pages were devoted to pipe, and several even to wire and cable, including hard drawn #9 copper used in the phone/tele./control line pole line wiring that paralleled pipeline R/W's.  Even wave guide was specified with some surplus from capital projects listed as stock items.

The next control system was Co. Owned and operated microwave/tone , and the latest, of course is internet SCADA, but I digress.

[WBear2GCR]

Ah, right, humor... sorry to have missed it!

If you had dumped in some bogus alpha-numeric string, it would have been more realistic.

One must recall that this was the time of the typewriter and the secretarial pool... thousands of women typing "stuff". The ironic part is that probably 99.999% of all of that stuff is landfill.

                               _-_-