M. G. Devour wrote: > > Yo Bob!! > > We have heard that the TDS-1 tester is not the best thing to use in > > judging CS and that the TDS meter is junk and doesn't work and is a > waste > of time and we're all *stupid* for being sucked into buying one > and > *you've* got to try to confuse things with facts... > > Actually, I'm wondering if your "ionic current" assertion is actually > entirely compatible with my "conductivity measurement" assertion and > we're just quibbling over semantics?
Hi Mike, thats right, it`s semantics mostly. The TDS-1 does what it was designed to do at a very low price, a most excellent tool. It will not count particles, or tell how big they are, or even tell us if there is dirt in the water. It`s not supposed to do that at all. What it does do is tell us if there are ions in the water, which is a good indication of minerals and/or metals in the water, since they usually produce ions or have ions with them. If the water is *deionized* (distilled) there is not supposed to be any minerals or metals or anything in the water. My distilled water will read 001 ppm which says there is not much of anything in the water. As we run a current through the water with silver electrodes in it some of the silver is released into the water in the form of ions. The TDS-1 tells us these ions are there and in what quantity. Thats all it`s supposed to do. > > I agree with you that it will only measure the charged particles, or > ions. If you measure things like sugar that are non-polar when > dissolved, you'll get nothing, nada, squat. Anything that's charged > (ionic) will show up, more or less well. > > Well how is that different than conductivity, huh? The only reason > something like water conducts is that there are ions in it. In the > case of metals or semiconductors, there are free electrons or holes > that keep the field charges from getting stuck in the lattice and > allow current to pass through. In aqueous solutions, however, it is > all ion transport, no? Thats right Mike, its ionic all the way. As more ions are in the water the conductivity will get better. The ionic reading is just another way of stating conductivity. As we make CS more ions enter the water from the electrodes and the conductivity gets better and the current becomes larger and larger. Because of the low impedance of LVDC supplies the current can runaway (thats not good) and needs to be limited. On the other hand HVAC supplies are high impedance and the current can not run away, they don`t need current limiting. > > I do know that the PWT and TDS both operate on the same electronic > principle. One of their engineers told me that much. One reads in > ppm, the other in units of conductivity. > > Did you measure the voltage on the pins of the TDS in both AC and DC > mode? With an electronic DVM, not analog? I have taken apart one of my TDS-1`s (and put it back together again) to see what is in it. It is a high impedance input operational amplifier (opamp in slang). The input is a bridge with temperature compensation for stable, correct readings at different water temperatures. The thermister is in the little round bump beside the two probes. The output of the opamp is then converted into a digital display via an ADC (analog to digital converter). The probes in contact with the water sense the ionic potential. A current flows in the bridge which the opamp amplifies to a usuable level for display processing. All this for just 15 to 20 dollars, depending where you get it from. > > I've got an oscilloscope buried around here somewhere. It's time for > me to see what kind of signal they're using to probe the sample. I'm > not inclined to believe that there is some effect of ions in the > water that can be measured passively without applying some signal. > I guess I`m being obtuse, here, but what voltage are we talking about? > I > just don`t see how you can get a potential to measure? No electric voltage (potential) or ac signal is at the TDS-1 probes. I have measured them and found nothing. The ionic potential of the water and whats in it provides the voltage which causes a current to flow in the input bridge. The bridge is very high impedance and only a very small micro current (microvoltage) is needed to cause current flow in the bridge circuit. Well where do we get this from in the CS? Anytime we disassociate ions from atoms (electrons) we have a potential (voltage) no matter how small. In a battery we disassociate them at a fast enough rate to get a large current flow. When we don`t the battery will be dead. The ions (electrons) will flow around the circuit trying to equalize the potential caused by the disassociation. Even in the CS we have disassociation taking place (if we didn`t there wouldn`t be any ions) and the small micro potential in the CS will cause a current (micro current) to flow in the TDS-1 bridge. Think of all the ions as small batteries wanting to equalize themselves through the bridge circuit. As a matter of fact, with the starved current technic the water is so saturated with ions I have measured as high as 65 millivolts in the water, just the CS, no power applied. It`s not magic, just think small. And all the TDS-1 needs is microvolts, not millivolts which is a thousand times larger. For your money your getting a heck of a buy. Putting a 4 inch long wire on the TDS-1 probes will cause it to read 5 ppm in the air, and when I blow on the wires the reading changes as the ions in the air I`m blowing cause changes in the air ionization which changes the ion flow in the TDS-1 bridge. Remember we like negative air ions for good health, but thats another subject. > So how would you really use the TDS-1 when you make your CS? I take a current reading every five minutes and a TDS-1 reading at the same time. I draw on paper a graph with a line for the current and a line for the TDS-1 readings. After a while you will be able to see the correlation of current to ppm (ions) and be able to make consistent batches of CS time after time. I have been able to hold several charts up to the light and see them overlay exactly for all batches. > Thats been my belief! I like the spec`s on the PWT model, though. It`s > the > equivalent of a 0-200 ppm TDS-1, I think. The testing range is > much better > matched to what we are doing. Costs about forty-something > bucks. Thats a good choice, but for the money the TDS-1 can`t be beat. I have several, and they all read the same, the agreement is pretty good. > > Mike D. > [Mike Devour, Citizen, Patriot, Libertarian] > [[email protected] ] > [Speaking only for myself... ] Bless you Bob Lee -- oozing on the muggy shore of the gulf coast [email protected] -- The silver-list is a moderated forum for discussion of colloidal silver. To join or quit silver-list or silver-digest send an e-mail message to: [email protected] -or- [email protected] with the word subscribe or unsubscribe in the SUBJECT line. To post, address your message to: [email protected] List maintainer: Mike Devour <[email protected]>
