Re: Thank you ken Martindale

[sfortt@ozemail.com.au (shayne)]

>Shayne,
>
>I use pressure compensation with a Scuba regulator so I don't need any
>modification of the seals. Also by placing the regulator at the lowest point
>in the Sub I have a slight positive pressure in the air spaces in my Sub,
>assuming the regulator stays at the lowest point.
>
>I think Minkota motors have enough room along the shaft to possibly install
>two seals although I have not tried it. Be aware that if you don't use some
>sort of active current limit in series with the motor a locked shaft will draw
>enough current to demagnetize the permanent magnets and effectively ruin the
>motor. The controllers offered by Minnkota have this feature  as well as my
>design and use the same switching frequency as my motor controller at 20 Khz.
>I'm not sure if all their motors have this problem but the one I am using
>does. It's a 70 pound thrust 24 volt motor. I didn't want to use their
>controller since it was $169 and mine cost me about $50 and I can fix or
>change it as I wish (as well as interface to a computer).
>
>Good Luck with your ROVs, if I can help any futher I will. Don't forget about
>the other vendors. Surf or crawl the Web for their Websites. I just got
>Minnkota's latest brochure which I ordered over their Website and they are now
>listing a 96 pound thrust motor that only draws 56 ampere from 24 volts. It's
>listed on page 25 of their brochure.
>
>Ken Martindale 
>
>Thanks again for your info. I have just received 2 Minnkota motors, 12 volt
model t-50 without the controller. You state above that you made your own
controller. Where can I get the information to make my own controllers. My
father is involved with the project and was an electronic tech for an
airline, so building it would not be too difficult if the information was
readlly available. I'm assuming this controller is a pcm controller.