I had some indirect correspondence with Ron Newman (via Mike) on 10/05/03 regarding LCD and PAR detection. I sent Ron my response, I also invited Ron to direct all LCD/PAR questions to me, more technical the better. I never received a response. This is the gist of it:
1. "Impedance". Ron asserts that rectified AC; as comes from a 25A Caswell rectifier, a battery charger, or any and all of the big stuff (100 Amps+) in commercial use is not actually DC, but rather "half of an AC sine wave". This is technically wrong. By definition; since the waveform (half-sine or otherwise) does not cross zero volts and become the opposite polarity it is DC. This defines a resistance, not an impedance.
2. It doesn't matter if the resistance changes with temperature, it will a little. When dissolution overtakes the anodic layer growth the resistance will go down. We are not looking for a specific value of PAR for detection; we are looking for a change in the direction of PAR, the resistance starts going down instead of up.
3. If you are anodizing a piece large enough to really raise the electrolyte temperature at 6A/sq.ft. , something around 10 sq.ft., you better have some type of cooling system. 10 sq.ft. will dump 15V x 60A = 900W of heat dissipation into the tank. If you were using standard anodizing (12A/sq.ft.) the heat load would be 1.8KW. Again; even in this extreme condition, when dissolution overtakes growth whatever resistance you have will go down.
It's clear that Ron has never tried to detect PAR; if he did he would see that it works, but he has his own commercial axe to grind. It's also clear you haven't either Potsked, but I don't know your reason.
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