here it is
Hi,
Yeah...I knew something was up when I saw those numbers....that's why I did the Icecap clone....here's another one of my theories...
VHOs are notorious for having massive dropoff in output for the first 100 hours. Say, it starts at 7000 lumens and drops to 5000 lumens. So...that's like going from 100% to 71% output. On top of that, most VHO ballasts are design to operate at 85% maximum output - to save power. So, thats 60.3% output at 100 hours. Now...suppose the Icecap does not drive it as hard...so that it's output dropoff is not as steep...say only 5%-10% loss (typical NO, T8 numbers). We are talking about 50% to 55% of the original VHO .... pretty close to a regular 60.3% VHO. So...that's why it doesn't really pay to drive tons of power in to a VHO. Part of the reason why VHOs fail so fast is the current that is passed through them...1.5A vs 430mA in a NO (regular) or PC (roughly the same current...but not quite).
So...I hope that explains why. It has nothing to do with high frequency drive blah blah blah... That fixes a different design problem. [img]images/smiles/icon_biggrin.gif[/img]
As for your PC vs VHO question...PC has more lumens and it is slightly more efficient than VHOs. The problem with PCs is that the actinics suck and lamps are expensive (55WPC costs more than 1 VHO). If you don't mind power inefficiency...MH is the way to go [img]images/smiles/icon_smile.gif[/img]
Hope that helps.
- Victor.
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