I need a 12v, 1kHz-12kHz variable frequency oscillator circuit, with as high an amperage into a coil as reasonably possible.

I'm considering making a device to test for myself the claims of vendors hawking "salt-free" water conditioning as a substitute for or supplement to traditional, ion-exchange softening. Why not just buy one? Because the vendors are charging $500-1000 for them, and it seems to me they are much simpler than that. They do offer free trial periods, and I may consider that.

This thread is NOT about discussing the merits of the vendor claims, only in the circuitry required to perform a test. I'm aware there's a very good chance this is a scam. Even the design raises an eyebrow; they've put what looks like a huge heat sink on a device that consumes 5W.

One of the leading vendors describes the treatment here and in US Patent 5,074,998 (expired, or expiring in 2011).

As far as I can tell, the idea is to flow your home's water through a solenoid coil made by wrapping wire around your piping. The solenoid is fed an alternating current:
"Electronic water softeners signal produces a unique square wave current that sweeps all the frequency responses from 1,000 - 12,000 Hz at a rate of 20 times a second." (from http://www.promolife.com/water-puri...c-non-chemical-water-softeners/prod_1320.html) The patent above mentions a similar range of 700-3000Hz.

The commercial devices use very little power, less than 10 watts for sure and generally 5W or less. They disclose that the "application voltage" is 12v, although I can't tell what the actual oscillator voltage is. If they are truly pulsing any decent current (and not just selling fish oil), they must be using some sort of efficient oscillator to get that current with so little power consumption.

Any ideas about a circuit design?

 

Gee, I like the ones that just strap on a magnet. No power, and about as likely to work.

Scams always have some condition, like the "square-wave current" description that can't quite be understood. Have fun trying.

 

Yeah, I was actually a lot more receptive to believing this until I saw how low the power draw was. They probably do that to make it more attractive costwise and for the greenies. Of course that also makes it an easier DIY project.

Glad to see you noticed the "unique square wave" comment. How can you not laugh?

The patent describes using a VCO, pulsing it several times a second (20Hz) to sweep over the frequency range. An obvious problem is that a flow of just 2 gpm through a 3/4" copper tube travels at nearly 18 ft/s. That means that a solenoid winding that covers 1' of tube will only "see" an element of the passing water for one cycle of the 20Hz oscillator. Hard to believe much can happen with such a brief treatment time at such low energy.

 

Years ago, a young friend (a computer engineer) got enamored with the idea of a permanent magnet changing hard water's properties to soften it (all the people on wells in our area have hard water). My first reaction when I heard him propose the technology was "What a bunch of BS".

But he was in magnetic treatment lust, so I designed an experiment to test the idea. I happened to have some magnets from a disk drive made by a company I used to work at. I knew those magnets had B fields pushing 1 T. So I soldered a piece of copper tubing to the bottom of a tin can and put the magnet around the copper tubing to treat the water per the published method of the people trying to hawk the magnetic softener hardware. I treated one can of water with the magnet and one without (i.e., the only difference was the magnet). To "measure" the effect, I cleaned a mirror and marked areas for the differently treated waters with a Sharpie marker. Then I used an eye dropper to place one drop each of the differently-treated waters on the mirror, including some distilled water. The results were the visual amount of residue left after the water evaporated. While certainly not quantitative, the results convinced him to go to Costco and buy a regular water softener that used salt.

I certainly won't comment on the basic idea you're evaluating, but I sure understand your desire to do the experiment yourself. I wanted to suggest the mirror method of qualitatively evaluating the treatment because it's so simple to use. Of course, some quantitative measure would be better. A few years back I built a microbalance based on the clever idea (I think it was a Scientific American amateur scientist article) of using the needle of an analog meter and feeding the right current through it to balance a weight load (use a meter with a mirror scale to eliminate parallax). It's a fabulous tool, but the hard part is coming up with mass standards. Nevertheless, they could do things with it like watch the mass loss from a tiny wet piece of thread due to the evaporation of the water. The other problem is that a tiny snort of air from a nostril can blow your carefully-measured little mass standards to hell and gone (guess how I know). I used the guts of a 50 μA meter movement from an HP distortion analyzer that gave up the ghost from some smoke damage from a fire.

You could use such a mass balance to perform careful quantitative analyses of the residual crud left behind after the water evaporates. However, you'll have to find a way to put identical volumes of fluid on the samples. Find a friend in a biochem lab and ask to borrow a micropipette. Check your technique with a low vapor pressure oil first.

 

...
I'm considering making a device to test for myself the claims of vendors hawking "salt-free" water conditioning as a substitute for or supplement to traditional, ion-exchange softening.

Don't try to figure out why fools give away money. Either avoid the 'scam', or join in and get some foolish persons money for yourself. Nothing you devise, no test or demonstration, will convince a fool that he is being foolish for believing these scammers.

I strongly suggest that you not waste time on this, and instead use your energies to do other, more useful things.

Anything else would just be foolish.

 

You could use such a mass balance to perform careful quantitative analyses of the residual crud left behind after the water evaporates.

Well, not really. They make no claim of removing anything, not even hardness, only nucleating crystallization and changing the crystal form of the carbonates, rendering them non-scaling. They even claim that hardness may increase as scale deposits throughout your system are removed. How long does it take? Probably longer than the trial period!

Oh, and kudos for doing actual science to answer the question whether these things work at all. One things certain, they don't truly soften water and they don't remove any other impurities either. So that makes them less useful right off the bat.

 

Don't try to figure out why fools give away money.

Sage advice, to be sure. There are a surprisingly large number of people that think these things are great, though. A placebo might get the same result but the details given in some of the testimonials are hard to explain if nothing at all was happening.

Back to the circuitry though, is there any reason you couldn't build one of these for just a few dollars? I mean, I already have the power supply and copper wire. I can't believe the commercial devices get more than 1A or so in the oscillating loop. Maybe it's more, maybe enough to be beyond a DIY challenge?

 

Of course you can build it, but first you need to determine the effective nucleation frequencies of suspended calcium carbonate crystals given their varied lattice angles and build a square pipe section to closely fit the superconducting square wave transducer coil. I'd recommend including a flow sensor in a VCA feedback loop to dynamically control the amplitude of the VCO and sweep generator.

I'm sorry, I just can't take this stuff seriously.

 

I'd recommend including a flow sensor in a VCA feedback loop to dynamically control the amplitude of the VCO and sweep generator.

Hah! Flow sensors are a part of the early patents in this area.

Well, this thread went straight to where I feared it would, and I'm leaning towards bagging any further work on this. Maybe for fun I'll just strap a couple of my big Neodymium magnets to my water pipe and see what happens. It might be easy to test an electric field approach for myself, but I've got better things to do.

For anyone that follows, I've since found two fairly good reviews of the technology and (big surprise) both conclude that the technology doesn't live up to the claims. Same conclusion as a 1996 Consumer Reports investigation. Sometimes maybe it helps, but not reliably.
http://www.csicop.org/si/show/magnetic_water_and_fuel_treatment_myth_magic_or_mainstream_science/

http://www.nmsr.org/magnetic.htm

 

Sounds like you're reasonably skeptical. Good. But there are pseudo-sentient beings out there who gobble this stuff down with nary a synapse firing. These wonderful products of our current educational system's output of critical thinkers are these charlatan's legitimate prey. I have no doubt that I could go back 50 and 100 years in the popular literature and find similar claims for all sorts of "magnetic" and "electric" treatments to solve or cure some problem. There's a sucka born every minute and another sucka willing to take advantage of the first sucka. Makes you feel good in a twisted sort of way...