I originally sent this in private e-mail by mistake. Will forward Vikki's reply shortly...
Welcome aboard, Vikki! I haven't had a chance to make your acquaintance before now. I have a long time hobbyist's interest in electronics myself, so I really appreciate your experiments and tinkering. I think what you saw happening was the usual fluffy buildup and dark roughened coating on the neg and pos electrodes, respectively, being dislodged and falling off when the polarity changed. I think Bob will encourage you to shorten the switching period to only a minute or two, per his experiments. The faster rate doesn't let much buildup occur before the states change so everything that's being driven off the electrodes stays smaller and doesn't have much chance to fall out of suspension. I have a question: Why are we even worried about H-bridges and relays, anyway? Aren't the logic outputs on a STAMP microcontroller or CMOS logic chip thoroughly capable of sourcing *and* sinking at least a milliamp or two? There's nothing that says you have to use 30 volts. Folks have used everything from a few volts on up with success. The only difference is how quickly the stuff gets made. Do you maybe have analog inputs for current monitoring and outputs that also could be tricked to sink/source current if cross connected? There's lots of possibilities there if so. In the system I've been running lately, I limit the current to only a couple of milliamps or so, to keep current density low enough to keep the particle size down, per Trem Williams suggestions. I use a simple current limiting resistor of a few kilohms in series with my 30 volt supply. I'm not switching polarity at all, but that would be the next step. So why not toss a couple of resistors in series with two logic pins that, combined, limit the output current to a milliamp or two when they're cross-connected through the cell? Then switch 'em every minute and see what you get. Try pulse modulating the two digital outputs with R/C networks on them to get an adjustable voltage to control cell current. Might be a problem with the switching transient, but, hey, who says you can't program a delay to let the current drop to zero before powering up the other side? Of course your analog outputs could do the same thing with a lower parts count. Lots of possibilities, there! Of all the low voltage ideas discussed to date, I believe that Bob's polarity switching combined with Trem's current limiting might make a very consistent and easy to run low voltage design. It would take longer to make CS, but would require a *lot* less monitoring. You would have minimal or no buildup on the electrodes and could run until you had as much silver in the water as you wanted to. You could do time or conductivity based shut-off with your controller as well, and perhaps even cell current integration for total silver content. Really deluxe stuff! It's the sort of stuff I'd like to see tried next. Anybody's welcome to give it a shot. Let us all know what you learn. Be well, Mike Devour silver-list owner [Mike Devour, Citizen, Patriot, Libertarian] [[email protected] ] [Speaking only for myself... ] -- 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]>
