Hi All,

This circuit is a 1 minute oscillating timer that reverses the polarity of two electrodes.
As this is my first circuit, I'd like another pair of eyes to review it for corrections or improvements. I also had a question about the power source.

I've assembled and tested everything except the upper two batteries, and I know that everything to the lower side of the blue line works properly. Thanks to this forum, I've ordered an H-bridge IC, and will be replacing the relay when that arrives.

As for the power questions: I want the relay/H-bridge to toggle a 27v circuit. Is it okay to place the two extra 9v batteries as shown?

also... does anyone have suggestions on what app to use for making diagrams? (I used paint... sorry.)

Thanks,
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What is the application? Why not use a wall transformer instead of low-capacity batteries? If changing polarity at the electrodes is necessary, why not use low voltage AC?

 

hi beenthere,

In this case I'm using batteries for 2 reasons: 1) portability 2) so I can compare the results to a similar AC electrolyzer.
Admittedly, I could also rectify AC current but the portability concern won out.

The specific application is to make a colloidal/ionic silver solution from distilled water and 2 silver electrodes. After that I will compare particle sizes and ratio of ionic to colloidal silver in various batches of suspension made with each of the circuits.
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The need for more than just a few milliamps of current may force you to use more capable batteries. As you mention some experimentation, perhaps you could make one with some DC supply and select batteries later, based on effective voltage and necessary current.

If you need to switch polarity at a rate of more than 2 or 3 Hz, an H bridge will do better than a relay.

 

Ack! Thank you for noticing... The way the chemistry works out, I'll need 2.64mA but on the diagram I wrote A instead of mA.

Right now it's switching every minute (.016667 Hz), so I'm looking forward to the H-Bridge. The relay was all I had on hand.

My main concern was how to wire the 27V electrodes and the 9v circuit. Will placing the batteries as shown fry the timer circuit?

-masked

 

Yes, that would create problems. The voltage applied to the electrodes does not have to be related to the voltage running the circuit. Just apply it to the common terminals of the relay.

 

Thanks. I'll just add a 4th battery and have 2 separate power supplies - one 9v and one 27v.