magnets

[ggunn]

Ok, the physics aside. The question begs why use a magnet when there are better, cheaper and easier solutions. My take on it is to use "velcro" which here at least you can get in ribbon form and sticks real good. I use it for loads of things and it definitely wont effect your signal chain.

Aw, c'mon Muttley, don't you want to 'aggle? ;^)

 

[muttley600]

Aw, c'mon Muttley, don't you want to 'aggle? ;^)

Nah mate, I know the answer as well and there is no point doing tests.

I didn't mean to question you it was a slip of the mouse. Still no need to use magnets though. Expensive and not practical for the job in hand they would work however. Learning physics the hard way is fun fun fun.....

 

[ggunn]

Nah mate, I know the answer as well and there is no point doing tests.

I didn't mean to question you it was a slip of the mouse. Still no need to use magnets though. Expensive and not practical for the job in hand they would work however. Learning physics the hard way is fun fun fun.....

No harm, no foul; I didn't take it that way.

What does sort of appeal to me, aside from the abstract argument, is that such an arrangement would allow one to change configurations by just sliding the components around.

Of course, all I've ever used is little wads of reverse-rolled duct tape. That works pretty well, too, and it's really cheap.

 

[Zaphod B]

The electrons in a wire generate a magnetic field, that's right, and in a coil, much moreso, because the fields from the parallel wires reinforce one another. A DC current will generate a steady state field, and an AC current will generate a varying field. This is why I've been talking about AC and DC voltages and currents. The AC component (where the audio info is) is not affected in any way by the DC component, be it electrical current or magnetic field.

If you have, for example, an output transformer of an amplifier driving a speaker, you can drive a DC current through the primary along with the signal and it will not appear on the secondary, even though the DC component is making a non-varying electromagnet of the primary. This is because inductance (which is a magnetic effect) works on AC current but not DC. When you apply Ohm's law to inductors, there's a "dI/dt" term, which is the change in current with respect to time, and if dI/dt = 0 (meaning the current is not changing over time, i.e., it's DC), the inductance term totally falls out of the equation.

The reason a magnet deflects an electron beam in a CRT tube is because the electrons have been accelerated to a high velocity. Electrons in motion generate a magnetic field, and that's a good example of that, but it's an example of two "DC" magnetic fields interacting. If electrons could be moved by magnetism alone, you wouldn't need a battery in your car; all you'd need would be a big permanent magnet.

Did I mention that I have a degree in electrical engineering? Sorry if I get long winded, but that's what engineers do, or so my wife will tell you... ;^)

Good post, ggunn, and I have a degree in EET so I understand it even though I haven't done much practical electronics analysis in quite a few years.

 

[rayc]

Someone PLEASE just try it!
Guitarist are, traditionally, so iffy butty about their sound I thought there'd be a chorus of concern. This matter needs an acid test - all physics & electronics aside - of being tried/applied hence my suggestion re running the mag around the cable at least to see if there's an influence.
I'll be happy to be wrong - I just don't want a youngun to damage something.

 

[muttley600]

No harm, no foul; I didn't take it that way.

What does sort of appeal to me, aside from the abstract argument, is that such an arrangement would allow one to change configurations by just sliding the components around.

Of course, all I've ever used is little wads of reverse-rolled duct tape. That works pretty well, too, and it's really cheap.

You can do that with velcro. The stuff you can get on the roll these days is VERY strong and is backed with carpet tape strength adhesive. Works a charm.

 

[andydeedpoll]

in this case, cost is essentially irrelevant - we have access to the magnets which would otherwise go to waste already, and the metal we'd use to back the base of the board... in fact, it's probably more cost effective than velcro

i still haven't had chance to try this, but i'll be happy to tell you what i find (if anything) when i do i'm hopeful i won't find anything though

Andrew.

 

[ggunn]

You can do that with velcro. The stuff you can get on the roll these days is VERY strong and is backed with carpet tape strength adhesive. Works a charm.

Can you get a wide sheet of either the "vel" or the "cro", so you could completely cover the board in one or the other? If one could do that, then changing configurations wouldn't mean moving or adding strips of the stuff to the board.

 

[Zaphod B]

So muttley and ggunn agree that a magnet - even a bigass magnet attached directly to the metal enclosure of an effects pedal - would have zero effect on the operation of the circuitry, regardless of what's inside? (Unkess it's got a tube in it, like the stuff Damage Control sells)

 

[ggunn]

So muttley and ggunn agree that a magnet - even a bigass magnet attached directly to the metal enclosure of an effects pedal - would have zero effect on the operation of the circuitry, regardless of what's inside? (Unkess it's got a tube in it, like the stuff Damage Control sells)

Actually, I don't think a tube would be affected, either. But even long, long ago when I went to engineering school, tubes were already "obsolete", and tube theory/apps wasn't taught, so I could be wrong. Possibly the electron leap between electrodes would be affected because the idle current is DC, like in the aforementioned CRT tube.

 

[Zaphod B]

Actually, I don't think a tube would be affected, either.

OK. I think I need to go back to school. Or at least reaquaint myself with some of my AC analysis books.

I still like velcro.

 

[Zaphod B]

But even long, long ago when I went to engineering school, tubes were already "obsolete", and tube theory/apps wasn't taught...

I got about 30 minutes total on tubes. All of my electronics education was small-signal stuff, even though I did have to get through all the standard DC and AC analysis. Not that you'd be able to tell, apparently.

Didja ever have to program a Motorola microprocessor in hex?

 

[ggunn]

Didja ever have to program a Motorola microprocessor in hex?

Oh, yeah. I was the proud owner of a Rat Shack Trash 80 with a Moto 6809 chip, and I learned enough assembly language to find out that I did not want to do bit-banging for a living. I did do some independent study on tubes later, though. I blackfaced my '68 Super Reverb and rebuilt an old Supro single ended 6V6 amp.

 

[Zaphod B]

I learned enough assembly language to find out that I did not want to do bit-banging for a living. I did do some independent study on tubes later, though. I blackfaced my '68 Super Reverb and rebuilt an old Supro single ended 6V6 amp.

I hear you loud and clear on the bit-banging, and I'm just thankful that there are people in this world who enjoy it.

One of the things I'd like to pursue after the kids have flown the coop is tube amp design or modification. It'll finally put some of my education to use, and that way I'll have bits and pieces of electronic gear scattered about the place to drive my wife crazy.

 

[ggunn]

One of the things I'd like to pursue after the kids have flown the coop is tube amp design or modification. It'll finally put some of my education to use, and that way I'll have bits and pieces of electronic gear scattered about the place to drive my wife crazy.

I'm already there. My daughter is 24 and out, and my wife is really tolerant of my gear all over the house and my musician friends over to play a couple of times a week, sometimes until 3 or 4 AM. I'm a lucky guy.

 

[Zaphod B]

I'm already there. My daughter is 24 and out, and my wife is really tolerant of my gear all over the house and my musician friends over to play a couple of times a week, sometimes until 3 or 4 AM. I'm a lucky guy.

Sounds like life is good. Here's to you!

 

[muttley600]

Can you get a wide sheet of either the "vel" or the "cro", so you could completely cover the board in one or the other? If one could do that, then changing configurations wouldn't mean moving or adding strips of the stuff to the board.

It comes in widths of about 3 inches so just double up till you have whatever width of base board you need. At least that isn't rocket science

 

[ggunn]

Sounds like life is good. Here's to you!

Thanks. I certainly have no grounds for complaint.