Hello Mike and Members of the List! If you are going to use two co-cathodes anyway, you might as well switch between them. This can be done by a custom modification of the AC full-wave rectifier circuit. The advantage is that it should produce a new way of mixing, electrical agitation of the charged particles in transit through the liquid. The power source to the modified full-wave rectification can be whatever AC voltage is desired from the wide variety of wallwarts available. The rectifier circuit can be breadboarded using a general-purpose diode like the 1N4002. Four will be need unless two LM334Z devices are used for a dual purpose as rectifiers as well as current limiters.
The added insulation can be avoided by simply mounting the coin so its perforated edge is above the water surface. Problems of variable contact resistance between coin and hook have not occurred in my experience, but might be avoided by the use of LM334Z's in the unlikely case it does occur. Sophisticated timing can be done with the newer types of Christmas light controllers. I just bought one at Lowes for about seventeen dollars. It is a Timex 7 day timer that can hold 20 different switching schedules. Whether your specifications can be met remains to be seen through experiments. Mixing by electronic agitation may not be strong enough by itself. Thermal mixing is axial and vertical. Rotomechanical mixing is horizontal and tangential. Electrical agitation is horizontal and parallelogram-zigzag, depending on placement of electrodes. Maybe some combination of mixing methods is for the best. Best regards, and Happy Thanksgiving to all! Matthew
