Thanks for reply and sorry I didn't see the other rpm message thread, I should have posted there
The reason I ask is...
I picked up a turbine body at a farm equipment auction, no blades hub, tail or controller. The only marking is Y2000 and Xiaxian. I guess a Chinese 2kw unit. Cleaned it up, fitted hub with 3.2 metre blades, made tail unit, mounted it on 6 metre pole, wired to 3 phase rectifier and measured dc voltage out in range 42 to 72 volts. So it seems to be a 48v turbine.
Connected it to a Classic 200 and took a guess at a power curve using Classics existing power curves.
It all worked and I saw 700 watts in a 28km wind.
Now I would like to build a more accurate power curve hence the idea of getting some data on rpm so I could construct a more accurate output watts at various rpm.
The nacelle can be accessed and there seems room to get some rpm detection electronics in there with a small lightweight li-ion battery. I have a flexible 8 watt 12 v solar panel which would wrap nicely over nacelle top hence the solar panel idea. Although placing a small dc motor inside belt driven from main shaft would be nice but would need some fitting..
I can get the slotted opto inside too.
I was also thinking of the clipper I am building to work with this turbine and an rpm data into the clipper logic would help with getting dump resistor values accurate and the voltage width for the classics PWM aux output.
Dgd