Salty Resistor

petemoore · February 06, 2011, 06:36:10 PM

Just add water...
I was getting V/R between ~0.0k through 20k.
Pile of salt 1'', some water, DMM set to 200k range.
Kind of hard to use, was wondering if there's a substitute for the water, say antifreeze or some solid...
Don't get salty ! I was just playing with:
VCR tape, couldn't get anything useful from this stuff, one dude said yeh, but the tape was too long for his application [a Midi controller], I probably didn't sample the right kind of tape yet or something.
Conductive component package, didn't get anything from the semi-opaque mouser stuff.
Yet to try the conductive foam [that opamps sometimes ship in]...
Open to suggestions, I couldn't find the carbon black pigment around here, and still want to investigate alternatives before ordering a jar of powdery carcenogenic substance.

defaced · February 06, 2011, 09:42:23 PM

QuoteKind of hard to use, was wondering if there's a substitute for the water, say antifreeze or some solid...

Pretty much any fruit/vegetable should be conductive. Pickles and grapes come to mind as two popular ones. Though you're probably not looking for an edible project.

km-r · February 07, 2011, 01:48:54 AM

you should prevent the solution from generating sediments. hahaha! good idea... but i think these resistors will need a voltage limit you might be doing electrolysis there.

PRR · February 07, 2011, 02:07:50 AM

http://www.theatrestrust.org.uk/resources/images/show/7075-salt-water-dimmer-at-the-alexandra-palace-theatre

markeebee · February 07, 2011, 05:50:24 AM

I think Paul gets the prize for the most obscure link on the forum to date. How do you find this stuff?

petemoore · February 07, 2011, 07:15:02 AM

Ghostly cool !
I thought there might be some houshold products which could cobble a resistor up.
Just imagine the ghnarphing I'd have recieved if there hadn't been a historical salt-dimmer for Paul to link to [thanks BTW !
Where does one find this kinda stuff !

R.G. · February 07, 2011, 01:05:41 PM

N.B.
The original dimmers were actually pickle barrels, using the leftover brine. The example at the Alexandra theater is actually a later, customized example.

The resistance varies by moving a plate up and down through the brine further/closer to a plate on the bottom.

I wonder how many stagehands they went through, with adjusting high voltage/high power line current by holding onto and moving a stick attached to electrodes in a salt water bath.

petemoore · February 07, 2011, 08:10:31 PM

It's not funny...

edvard · February 08, 2011, 11:22:08 AM

And another Mojo part is born...

"How does that CluelessTronics SuperCrapFuzzulator get the 'squeezy' high end?"
"They use saltwater resistors in the feedback path of the second op-amp."

emstin1 · February 08, 2011, 06:35:52 PM

I've seen rusty metal plates with a nail as a stylus...playable resistance. Not sure how applicable that is though.

Top Top · February 08, 2011, 11:27:03 PM

Don't be salty just because you can't get that toan...

birt · February 09, 2011, 01:51:50 AM

Quote from: PRR on February 07, 2011, 02:07:50 AM
http://www.theatrestrust.org.uk/resources/images/show/7075-salt-water-dimmer-at-the-alexandra-palace-theatre

that is a very nice website.

i have learned about salt water dimmers at school. (i had a theatre tech education and we also had to know the history of our job

)

Taylor · February 09, 2011, 02:08:13 AM

Probably most people here know this already, but pencil graphite on paper makes a nice fixed or variable resistor. Drawdio makes fun use of this.

buildafriend · February 09, 2011, 02:25:34 AM

my technology teacher recently mentioned that! he said you can use pencil lead as a resistor. i was wondering how many companies have uncoded resistors or things that dont look like resistors in their circuits for protection purposes. i heard fulltone really protects their circuits.

Taylor · February 09, 2011, 02:32:31 AM

See here, but I haven't ever seen anybody do anything that dastardly. Generally if somebody wants to protect their design, they just pour a bunch of black epoxy goop on it.

buildafriend · April 04, 2011, 02:21:17 PM

Quote from: Taylor on February 09, 2011, 02:32:31 AM
See here, but I haven't ever seen anybody do anything that dastardly. Generally if somebody wants to protect their design, they just pour a bunch of black epoxy goop on it.

Hahaha that article was a pretty good laugh. Now I cant help but wonder how many clones we are making that will never be the genuine article.

petemoore · April 04, 2011, 03:16:40 PM

A photocell, or for better precision perhaps adjustable scales of resistors that can add to 10,000 ohms.
So many scale nodes on an adjuster, next range on next adjuster...the scales all aligned as best possible.
That or digital.

News:

Salty Resistor