Equatorial Mount

[Dan M]

Among other things (like I need another re project) I've been looking at using parabolic reflectors (dish and/or trough)to generate some heat.

It sounds like the easiest way to do this is with an equatorial mount, a simple led tracker (I've got lots of links) and a single axis control.  I understand I'll still have to adjust the elevation every once-end-a-while.

Questions:

How often do you need to adjust elevation?  Daily? Weekly?  I assume around the solstices it's less often than around an equinox.  If this is wrong let me know.

Also, is there some data table around for the elevation and azimuth for an equatorial mount for different locations of the globe?  I was thinking of installing the axis and sighting down the length of it to line it up with the north star.  Would this be close enough?

Thanks in advance,

-Dan M

[troy]

If you just want to make heat, a visual alignment with Polaris (North star) along the main rotational axis will be fine, depending on the size of your receiver (target at focus).  Your dish most likely will have focus errors larger than any error you get with a careful visual alignment to polaris, due to the approximations in the curve of your reflective surface(s).

Yeah, like you need another project. Just like my house.  My real job is 50 hours a week, it's our anniversary this week, so we want to do something special to celebrate that, I'm getting real close to a functional co-generator, but I need to make just one more fitting for the water jacket connection, etc.

Just when I feel like I'm getting a little bit caught up with all that, my wife calls me from work and says they're cutting down two 70' maples across the street with a big sign that says FREE WOOD.  So now I have five or so tons of black maple in my back yard to cut, split and stack.

Good luck and keep having fun!

troy

[arc]

Thanks for the tip on the alignment with polaris Dan, never really thought about it but sounds like a simple (but very effective) way to "get on track".

Troy,

Is that black maple any good for woodworking projects?

We have mostly big leaf maple here, I often pull pieces from the woodpile, saw them up with the bandsaw and stack them to cure for a while. Later, once seasoned and aclimated to being indoors, I run them thru the plainer to make nice, birdseye or gnarled grain jewelry boxes out of them.

Sorry about getting "off topic" here, just love woodworking, what can I say?

arc

[Dan M]

You're missing the obvious solution to the whole thing.

What wife could possibly resist an anniversary present of a brand new shiny chainsaw and log splitter.

Have Fun,

-Dan M

[Volvo farmer]

If you're using an old sattelite mount, there's a big threaded rod and a couple of nuts on the back to change elevation. This rod can be replaced with a second electric actuator from another satellite dish. Those actuators will run on 12 or 24 volts so when you need to adjust for elevation, it becomes a five second process of bumping the switch. If you want to get really crazy about it, those actuators have a reed switch in them and you can actually count the pulses to know how much it has moved. You could record how many clicks you need to bump the thing through one season and do it from your living room without even looking at it from then on.

And yes, the sun's daily elevation appears to move faster during the equinoxes. It's like a pendulum.

[troy]

In all fairness to my amazing wife, she helped load and unload all of it.  I cut it and split it and she stacks it all on the porch and takes care of the woodstove duties.  

Plus, she let me build my co-generator in the basement, so there's definitely some sound and vibration issues that she puts up with that many "ordinary" wives would absolutely not tolerate.

Have a lovely day,

troy