Solar Dish Aiming & Tracking System: Electronic System Block Diagram

March 29, 2005

It appears that we are going to have an early spring this year. Birds have returned already and snow is melting rapidly.

On the international scene we just saw another major earthquake hit Indonesia -- that's two major earthquakes within 100 miles of each other in just three months! Volcanic activity is picking up at Mt. St. Helens, and major melting in Greenland and the Arctic Circle is beginning to affect Gulf stream flow.

The handwriting is on the wall, and Nikola Tesla's predictions are coming to pass. In the early 1900's when he was actively developing his turbine, he said that the use of piston engines rather than his turbine for global motive power would lead to widespread pollution-related catastrophes, and now the predictions have come true. -- But this is just the beginning.

By 2008-2010 world oil supplies will begin to fall behind demand. Prices for fuel will skyrocket starting this year, and the U.S. will push to relax coal burning restrictions to take up the slack. Bush's short-sighted energy cartel scheme is to inundate the U.S. countryside with power lines, and create a huge central power production facility just over the Texas-Mexico border. If you think global warming and pollution are bad now, "You ain't seen nothin' yet!"

To counteract a lot of this Howdy-Doody Knucklehead activity, we have a few interesting projects in the works.

Experimenter's Tesla Turbine

Presently we are downsizing our turbine from 10 inches to 4.5 inches. This will allow serious experimenters and developers to create real applications. These smaller turbines require much less energy to spool them up, and they fit better into our philosophy of distributed power down to the individual home level.

We are working with our local laser cutter to begin manufacturing 4.5-inch disk components which will allow us to offer rotor disk kits in the near future. Since disk machining is the most complicated part of building a Tesla turbine, we are soon to offer a complete rotor kit to get more of our club members into the experimental arena.

Solar Turbo-generator

At the same time we are continuing our solar engine design and development efforts as our contribution to global improvements. Ultimately, the world must shift from fossil to renewable fuels. Most people believe that hydrogen is the fuel of the future. By using a free energy such as the sun, we are able to produce that future fuel -- hydrogen -- now. These smaller turbines, from 4.5 to 6 inches, are ideal engines for homebuilt solar concentrators.

Since we can't persuade politicians and industrialists to do the right thing, we can enter into the space age on a grassroots level. Everyone can become an energy producer and cut out the power extortionists.

This month we are going to study a block diagram of the electronic system, which incorporates both the aiming subsystem and dish-concentrator drive subsystem. As we mentioned in last month's discussions, one of our goals is to create a stand-alone sun tracking system. 

Continuing along these lines, we also need a simple, low-cost but intelligent controller that may be easily updated with future enhancements. The best way to accomplish this is with an embedded processor. As we mentioned previously, we intend to use an IBM compatible PC for our development "front end", but it is the target processor (in this case a Microchips PIC processor) that will act as the onboard robotic "brain" to control aiming and tracking functions.

Electronic System Block Diagram

Electronic System Block Diagram Description

The heart of the concentrator tracking system is a PIC 18F84 processor. The CPU is a low-cost component - under $10 - that can be ordered from suppliers like DigiKey. Experimenter project boards can be ordered through ME labs. A complete processor board (not including actuator drivers) can be built for about $20.

The target acquisition module consists of four LDR's (light dependant resistors) or photo-eyes arranged in a quadrature array -- two vertically, two horizontally --  or both pairs mounted diagonally to the sun's path. 

The processor uses the LDR pairs as differential comparators. If light falling on one of the LDR's is stronger than the other, the corresponding actuator moves the concentrator up/down, left/right until the comparator signals are equal.

The actuators and actuator power controllers we are using are surplus components from the C-band satellite dish era. These C-band dishes and satellites are still used today, but are rapidly being replaced with small dish systems. So there should be a lot of this equipment being given away by former owners. You can also check with local dish installers for older C-band equipment. In future editions of the PTBC we'll cover exact components and their interconnections, but for now we are studying the system overview.

System Description

The last part of the system block diagram is the PC serial interface. 

We discussed previously the fact that our embedded processor will drive the concentrator/dish autonomously -- with no intervention on the part of the user. That's true, but there are times when you may want to override the usual cycle and control the dish remotely. That's where the serial interface comes in.

In our design we will incorporate a software "hook" to allow us to take control of dish movement remotely using a PC compatible -- desktop, notebook, etc.

A serial interface will also allow us to patch in other modules like real time clocks, ephemeris data, etc.

Conclusions

So there you have a good first look at an intelligent robotic system for finding and tracking the sun in two dimensions -- azimuth and elevation.  As you have probably already guessed, this same system of tracking could be applied for other purposes such as laser guided missiles, etc. -- but we'll focus our efforts on much more beneficial programs such as power production.

Next month we are going to look at the targeting subsystem in much more detail. We'll show exactly how the discreet electronic components are interconnected and how they interact with the embedded processor.

Until then, continue gathering materials for your solar generator -- Spring is already here and the weather is right for you to begin building your own backyard free-energy turbo generator.

One last thing -- we need your input. As your project progresses, send in your photos and experimental results. We're all in this energy crunch together, and we'll get beyond it through unified action.