Comments on: Why add a capacitor to the Anodizer? http://mrtitanium.info/2008/08/06/why-add-a-capacitor-to-the-anodizer/ Information about art, medicine, and jewelry involving anodized titanium and niobium Tue, 20 Sep 2011 15:44:50 +0000 hourly 1 http://wordpress.com/ By: MrTitanium http://mrtitanium.info/2008/08/06/why-add-a-capacitor-to-the-anodizer/#comment-57 Wed, 06 Aug 2008 16:19:22 +0000 http://mrtitanium.wordpress.com/?p=25#comment-57 It’s not the resistance that changes, but rather the voltage drop at the anode. Specifically across the oxide layer.
I=V/R, but V = (Vsource – Vanode). The resistance doesn’t change, just the effective voltage.

It’s not that a rippled voltage lets you get higher colors (in the short term).
It’s that the rippled voltage displays a deceptive voltage reading.
If you switch the capacitor in and out at a fixed rippled input voltage, there is about a 15% jump between the Peak and RMS values. But the peak (what titanium cares about) doesn’t change significantly.

A 10 amp circuit should be enough for a muffler. You might want to use a big light bulb as a current limiter (maybe a pair of 500w halogen quartz tubes in parallel, or a space heater). Or else, watch the current and turn the voltage up to keep it at the limit until you reach your desired voltage.

]]> By: Tony http://mrtitanium.info/2008/08/06/why-add-a-capacitor-to-the-anodizer/#comment-56 Wed, 06 Aug 2008 14:53:02 +0000 http://mrtitanium.wordpress.com/?p=25#comment-56 Interesting. Resistance increases as the part anodizes and builds the oxide layer?
I didn’t consider that but it makes perfect sense.

Conversely, when you mention the difference between peak values and RMS values (given the same supply power) does this mean unfiltered supplies can potentially anodize to higher levels?

I ask because I have large parts to anodize (polished titanium mufflers) and it may be difficult to achieve the associated current densities.

Thank you,
Tony

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