Jazzbass5 Posted November 8, 2020 Share Posted November 8, 2020 I'm in the process of making my first chlorate cell and should receive my anode and cathode this week. My question is how do I calculate surface area of an expanded metal sheet anode? Link to comment Share on other sites More sharing options...
WSM Posted November 9, 2020 Share Posted November 9, 2020 I'm in the process of making my first chlorate cell and should receive my anode and cathode this week.My question is how do I calculate surface area of an expanded metal sheet anode? The simplest method is to calculate it as if it were solid. The tremendous surface area of MMO on titanium mesh (on a microscopic level) is nearly equal to MMO plated solid titanium sheet. It's close enough for easy calculations. Read through my Blogs for calculation formulas. WSM 1 Link to comment Share on other sites More sharing options...
Jazzbass5 Posted November 18, 2020 Author Share Posted November 18, 2020 Feeling all mad scientist like today. My cell is running at 5 volts and around 12 to 13 amps. Link to comment Share on other sites More sharing options...
Jazzbass5 Posted November 18, 2020 Author Share Posted November 18, 2020 The PC supply I was using was kicking into protect on the 5vdc rail so I decided to make the power supply out of a (rewound) Microwave transformer instead. Link to comment Share on other sites More sharing options...
Arthur Posted November 18, 2020 Share Posted November 18, 2020 If you use MMO then a transformer supply will likely work but there will be voltage ripple. If you use that supply with a platinum electrode the ripple will likely cause the platinum (it's almost invisible!) to come off the anode and it's then wrecked. Ripple kills Pt electrodes, PC PSUs have nearly zero ripple. The easy way to control the current, assuming you have an ammeter in circuit permanently, is to add a foot of wire into one or both leads, Make yourself a set of leads double your present length and if needed cut a bit off. My first set of leads sent a 60a psu into closedown my second longer set of leads started at 15A and with a trim passed 25A which suits me, the electrodes and the cell best and under runs the psu so it runs cool which is good. You need the cell away from the psu to prevent corrosion from spray/mist. Link to comment Share on other sites More sharing options...
Jazzbass5 Posted November 18, 2020 Author Share Posted November 18, 2020 I'm using a MMO anode, titanium Cathode, and I've filtered the DC output so there's minimal ripple. As far as an ammeter I have a set of leads hooked into the negative side to ground and shunted with a switch, when I want to check the current I just plug in the leads and flip the switch off, check my current, then flip the switch back on. It's pretty consistent at 12 to 13 amps with an average voltage of 4.9 to 5.1 vdc. I found that the PSU worked fine on the 3.3 vdc and 12 vdc rails but it was very touchy on the 5 vdc rail kicking into protect often. It was given to me and may have some issues I don't know about. I'm into my 3 day and there's a very nice layer of crystals on the bottom and I'm looking forward to the harvest! Link to comment Share on other sites More sharing options...
Arthur Posted November 18, 2020 Share Posted November 18, 2020 If you switch the ammeter in and out its certain that the current unmonitored is different from the monitored current. Over current kills electrodes psu's and defeats end point guestimation. Link to comment Share on other sites More sharing options...
Jazzbass5 Posted November 19, 2020 Author Share Posted November 19, 2020 My meter is a decent high end Fluke 87. It shouldn't change the resistance much in the circuit, also, the current average during measurement is well below the maximum current rating of my Electrodes. But I will look into that. Link to comment Share on other sites More sharing options...
Arthur Posted November 19, 2020 Share Posted November 19, 2020 You shouldn't have a decent meter anywhere near a electro cell they like to be clean and dry. Look out a cheap meter that stays in circuit all the time. Link to comment Share on other sites More sharing options...
WSM Posted November 30, 2020 Share Posted November 30, 2020 (edited) You shouldn't have a decent meter anywhere near a electro cell they like to be clean and dry. Look out a cheap meter that stays in circuit all the time. I agree. Using a high quality VOM near the cell risks the meter. To monitor the amperage going into the cell (or coming out of the power supply), I use an inexpensive digital ammeter combined with a matching shunt, purchased on eBay for roughly $10 US. Ebay purchases from China can take a very long time to arrive these days, but I used to get such items delivered in as soon as 10 days in the past. Again, look through my posted blogs to see samples of what I'm describing. My personal favorite digital ammeters are the ones with lighted LCD displays, which have very low power consumption. WSM Edit: the ammeter is typically wired in series with the negative lead from the power supply. The digital meters with a shunt usually come with wiring descriptions or instructions can be downloaded. The shunt runs almost all of the current to the load (the cell in our case) with only a tiny amount of the current diverted to the meter for accurate measurement of the current flow. They are a very good way to track what amount of amperage is used by the cell, and for calculating end-of-run. Edited November 30, 2020 by WSM Link to comment Share on other sites More sharing options...
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