Summer wrap-up part 2 (The problem with shade)

If you’ve noticed in the image of the solar panels in their natural habitat (my backyard) you’ll see that much of it is shaded.  This isn’t always the case, however it’s very much the case after mid-August once the sun has declined enough in the sky and the foliage from the trees is in its fullest bloom.

This presents a problem for those that might be in slightly more wooded areas that still would want to use the power of the sun to gather electricity.  So how does one get around that?

Cells could be mounted higher, certainly, but that might be an impossibility for land that’s surrounded by very tall trees.  Cells could be spread out to various sunny areas, but they’re not going to be efficient as they’ll most likely only be in sunny areas for part of the year.  Additionally, spreading them out means longer wires being run and an increase in power loss along this wiring.  Plus, solar panels get pretty gross over time and they need to be accessible enough to give a good cleaning.

So let’s make a solar panel that goes where the sun is. The concept goes like this:

  1. An array of batteries is stored in a housing, all of equal physical size and capacity
  2. A robotic arm takes a discharged battery out of the housing and places it on a mobile bot
  3. The robot navigates the land using GPS, radio communication to a central server, and various sonar/infrared sensors to avoid obstacles and find a nice sunny spot.
  4. It parks on the spot and deploys a solar panel to charge the battery it’s been assigned, along with its internal power source.
  5. Once charged, it navigates back home where the robotic arm takes the fully charged battery and places it back in the bank.
  6. It then loads another discharged battery onto the bot and the cycle repeats.

Seems simple enough, right?  Doesn’t seem economically practical at all unless the swarm of bots doing this is big enough.  Probably still isn’t a break-even point in there.  Don’t care, it’s neat.  So let’s get started.

 This is the basic construct for a platform that will bear the weight of the battery.  It will not have a motorized drive-train as there would be a huge draw of power just bearing the weight of what is above it.  It’s made up of a few parts from a Tamiya Tracked Vehicle Chassis.  For this project I used a total of three of them.  They’re about $15 a pop on eBay.

Through this base I run two 3/16″ smooth and one 1/8″ threaded rods.  This will connect to the drive trains and allow it to move closer and further from them, allowing the power of the chassis and the weight of the battery as an anchor to articulate the panel.

 

Here it is tied to the chassis, each of these have a drive train and motors attached.

 

 

 

A motor is attached to the back with gearing to turn the threaded rod which is held in place at the connection point to the drive train chassis, articulating back and forth respective to the circuit’s polarity.

 

The wiring is snugged inside of some acrylic tubing and housed above to keep things nice and neat.  What isn’t pictured at this point is an additional drive-train attached to the front and mounting brackets for the panel.  Because I’m lazy and didn’t take any more pics.

The battery you’ll notice has securing brackets.  These are spring-loaded so that lifting the battery swings them away from the terminals and lowering the battery connects it to the terminals automatically.  Once complete, the system will detect a power-on with the connection of the battery, secure it with additional articulating power-driven latches (not pictured, but done) and run some self-tests.

Time to see how this thing handles the backyard terrain.  As I’m writing this I know the results of said tests but you’ll just have to wait until I get around to telling you about them.

 

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No, I said I need some “juice”

One of the things I’ve noticed about electronic devices is that they all, unequivocally, run on electricity.  Microcontrollers and small motors and actuators and sensors and such are also fairly picky regarding the voltages they’re interested in using.  Primarily, microcontrollers require either 5V or 3.3V of power with very little tolerance away from their ideal supply.  The flow thus needs to be very regulated.

To do this efficiently a specialized power supply is often required.  Hobbyists with too much money at their disposal opt for bench supplies that have perfect little power nubs at different voltages and lots of fancy meters.

I don’t have too much money so I decided to see what I could do to make my own:

You’ll note that by checking out the back of it, it’s actually just an ATX power supply I’ve re-purposed from an old PC.  The wooden carriage for it is a few slabs cut from a desk that has long ago been retired.  One of those ones that you have to put together yourself alone in the dark of your apartment while you wonder about what might have been as you scrawl through useless misdirections and absent hardware.  The stain for the wood is called “Anything But Particle Board” and doesn’t match at all with the PCB mill I’m working on that’s positioned next to it.  The front piece isn’t attached yet, so the wiring is a little exposed at the moment.  Makes for a better picture/story.

The top of it has a power switch, a voltage supply indicator light, which is illuminated when the supply is able to maintain all regulated voltages given the current power draw on it.  It’s basically an “all is well” light.  Above that is a reset button, and to the left are 4 terminals, for 3.3V, 5V, 12V and ground.

A nice aspect of ATX supplies is that they are wired with a non-mechanical on/off feature that allows you to turn it on by sinking the power on one of it’s pins.  It also has a constant standby 5V output.  By grounding the power pin the supply is turned on with the switch I’ve installed.  By shorting that with the standby output, the reset button allows it to power down and restart.

Another bonus feature of the ATX supply is that it will cut off its voltage if it detects a short circuit or an unsafe draw of power.  This means that it will shut down as soon as it detects itself firing watt upon watt of electricity through your overweight, out of shape shell of forgotten dreams so that you can live another day to ponder the decisions in your life that led to this point.

Sleepless boys make all the toys

Not finishing projects is sort of my thing.  Finishing them and taking them apart when I’m done is also my thing.  But against all odds work as recommenced on the CNC mill.  Primarily because I really actually need it to get done so I can put it to work manufacturing parts for other projects.

Now all three axis are running on balanced threaded rod, powered by three 1.8°/step stepper motors:

Back side with cat in background offering look of approval.

The z-axis has a ridiculous gear ratio to ensure that lifting the mechanism is pretty strain-free.

Each motor was tested, everything runs, and holy shit the thing is loud.  Some dampening will be needed but for a prototype, no complaints.  The motor is being readied for mounting.  It is a 6.2v motor that will be cranked up to 12-14v for a little extra rage.  Unfortunately, the actual area it has to work with is 7″x5″x1″, which isn’t huge.  But this is a proof of concept and if it works I’ll make one that’s much (much) larger.  A greater z-axis is  going to prove critical I suspect.

To actually run this, I have a few stepper motor drivers from Texas Instruments.  Or I might just make it run directly from a dozen or so transistors and some serious power switching that will be coupled with a computer’s USB port and special drivers (that I’ll have to make) to stream bits of data directly to shift registers.

Bedtime now though.

Green machine

One of the nicest things about not having a woman around when you’re trying to get stuff done is not having a woman around when you’re trying to get stuff done.

With that in mind I started tossing together a CNC machine that will be able to mill wood, plastics, and PCBs using the RepStrap idea of tossing something together to make the parts for a more permanent machine.  This will be used mainly to create parts for a 3D printer and to properly mill a replica of itself that will be perfectly machined.  Once complete it will be dismantled and its parts will be recycled to make something that runs much more efficiently and looks a fuck of a lot prettier.

Also I’m doing it entirely with hand tools.  Just a hand saw, power drill, and battery-powered Dremel.  With batteries charged off of the solar panel.  Hence the title.  Fuck it.

Here’s a quick pic of what I have so far.  More later, maybe with plans or something:

Yes, that’s a first aid kit in the background. Yes, I cut my thumb open. Yes, it was a hand saw. Yep, that’s pretty sad.