Author Topic: introduction  (Read 938 times)

vibert c

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introduction
« on: June 08, 2014, 07:33:42 PM »


Interested tree hugger from Ottawa Canada
You have aroused the curiosity of a 79 yr old radio amateur that has had ambitions since 1993 to intensify the solar flux on water heating panels.

This work by Gabriel may just inspire me to pick up the soldering iron and delve back into electronics once again.  My background has been varied from ďJack of all tradesĒ to internet junkie as I mastered touch typing back in 1951.

As a new student of the arduino Iíll be slow getting up to speed.  The magic that escapes when a prototyped circuit finally blooms into life has always been as satisfying to the ego as learning to ride a bicycle/unicycle.

Whilst digesting every word of text under the heading Understanding Heliostat Targets, Targetís Altitude; ďThe input range for a targetís altitude is greater than or equal to -90 degrees and less than or equal to 90 degrees. (-90 ?  targetís altitude  ? 90)Ē,  my brain .faded.

Please verify the greater than & less than symbols are correct in the bracketed text clipped above.
Less than or equal to; more than or equal to; how can the identical symbol mean two different things?

Please tell me it is a typo that word processors canít handle.

It appears again under the heading Azimuth

The input range for target azimuth angles is greater than or equal to -180 degrees and less than or
equal to 180 degrees. (-180 ? targetís azimuth ? 180)Ē


Vibert C


Gabriel

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Re: introduction
« Reply #1 on: June 09, 2014, 05:04:26 AM »
Hi Vibert, and welcome to the forums!

The Arduino is generally pretty easy to use. The hardest part I think is probably just figuring out how to install drivers and upload your first program. Well OK, maybe it's not the hardest part, but it is at least one place to get stuck.

The less than and greater symbols are definitely worded correctly, albeit confusingly I guess.

You could say either "the target's altitude is greater than or equal to -90 degrees"
Or you could say either "-90 degrees is less than or equal to the target's altitude"
If you think about it they do mean the same thing.

I have a B.S. degrees in mathematics with a minor in physics, so I have had a LOT of classes based heavily in math. I may have picked up the phrasing from one of my professors, or maybe all of them, or maybe it's just how I pronounce things in my head since it makes more sense to me to put the subject of the sentence first. I don't know, I've never really thought about it before. :)

Either way, it might be easier for me to just say something like "you can set the target's altitude value anywhere between -90 and 90 degrees".

Gabriel


vibert c

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Re: introduction
« Reply #2 on: June 11, 2014, 06:53:15 PM »
Thanks for the welcome Gabriel.
How heavy are these mirrors that you are moving with the available stepper motors?

My hot water heating panels might weigh 22 lbs each and I have three of them.

I have found that wheel chair dc motor drives are available free to those who ask in the proper place for them.  The have built in worm drives.  Max rpm with the built in controller is 70 forward and much less in reverse.

Is there a way you know about to utilize these for heavier duty?






Gabriel

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Re: introduction
« Reply #3 on: June 12, 2014, 06:24:01 AM »
I guess the mirror is probably around 20lbs-30lbs. Theoretically, as long as you counterbalance the weight of the collector it's more of a matter of overcoming the inertia to get the thing moving. The Arduino program has acceleration built into it which helps. Having a large gear ratio also makes a big difference obviously.

In my experience though getting the gears to mesh together and making sure things line up really well so that everything moves smoothly is the ticket to avoiding problems. If things don't line up right, having more powerful stepper motors doesn't seem to really matter.

I don't have any experience with wheelchair worm drives. I would suspect that the quality would vary considerably depending on the manufacturer. Some might be fine, others not so much.

I personally have taken the route of building the worm drive from scratch. I get the gears from sdp-si. They have plastic gears which are pretty reasonably, but you can also get the gear made in brass and the worm made in steel. They are a lot more expensive, but I'm sure they can hold up to a lot more abuse.

I have an assortment of basic machine shop tools that help me make things accurately though. Building the worm drive from scratch might be too much of a pain otherwise.
« Last Edit: June 12, 2014, 06:28:54 PM by Gabriel »

Paul L

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Re: introduction
« Reply #4 on: June 12, 2014, 09:10:21 AM »
Hey Vibert C,

It's always nice to see a fellow canadian treehugger on the site!  Welcome aboard! :)

It sounds like you're thinking of directly moving your solar water heating panels using the "sun tracking" option.  You may have your reasons as to why you'd want to do this, but as an alternative, I might suggest you use the heliostat setting instead to direct the light towards the heaters.   That way, you could mount a large mylar mirror that weighs significantly less (though the mylar would most likely have to be replaced each year...).  In my opinion, using it as a heliostat is a more versatile setting since you can select multiple targets - i.e. if you have enough hot water saved up, you can switch targets to daylight or heat a small room or dry fruits and veggies or get that tan you always wanted or.....you get the idea.

As far as the wheelchair worm drives - the program works using stepper motors.  I'm not sure if there's a workaround that uses regular DC motors that are used in the wheelchairs, which is why I removed the original motors from mine and replaced them with stepper motors.  It was a fairly easy process that involved drilling and tapping a few holes and grinding down the shaft of the stepper motors to fit into a slot in the gearbox, but I can't say for certain that they will all be that easy.  If you do choose to use a wheelchair gearbox though, I recommend you try and find one that has the drive shaft that extends to both sides of the gearbox like the one seen in this video - https://www.youtube.com/watch?v=zDQ2MCK4T4M, since it will make it easier to balance and attach either your water heaters or mirror.

Cheers,
Paul