Take two old scanners, two VCR’s, a stereo amplifier and tape deck. Place on a table with an ample supply of screwdrivers, wire cutters and other tools. Mix in a dozen middle school kids and observe the results!
As you might expect a little chaos appears. Chaos is good… Embrace the chaos! Use the result to have a little fun while learning.
A few electronic sacrifices await the arrival of the students.The event is STEMpede, a day filled with science, technology, engineering and math at the Parker School here in Waimea. With Keck Observatory essentially right next door, it makes sense that our engineers and astronomers can put on quite a day for the kids.We were joined by one of the engineers from Liquid Robotics and a couple local physicians and paramedics for a variety of activities and talks.
I was not going to simply talk, I have always believed learning is best done by hand. Some of the gear was from my own garage, some off the electronics disposal pallet at work. A lineup of old electronics greeted the kids, then I opened the tool-bag!
This is the rule for household appliances. I would just prefer that it not be a two year old microwave that I had installed into the kitchen cabinetry. Yes, I can probably fix it… after I dismount it and lower it out of place. A task much easier typed than done. No matter, I am on-call this weekend. I will be around the house all day anyway, may as well get something productive done.
An over-the-stove microwave costs a few hundred dollars, too much to just run out and buy a new one. Not enough to justify a repair call. I do not even want to think of what it would cost to get a repairman out to the house. Driving from Kona? Hawaiian rates? I can think of few easier ways to get robbed.
Microwaves are pretty easy to work on, just get the cover off and everything is right thereI can fix this. Microwaves are relatively easy. Plus, it is an LG, you can actually buy the parts without going through an authorized extortionist. I have long ago learned not to buy certain brands, restricting appliance purchases to companies for whom you can actually find the manuals and buy the parts.
Another exhibit built for public outreach functions. It was completed and used for the recent W. M. Keck Observatory open house. You will also be able to see it at the upcoming AstroDay fun in Hilo.
Ray-tracing is a standard way to analyze optical designs. The technique allows the optical designer to follow the path of each ray of light through a system of lenses and mirrors. While ray tracing used to be done with pencil and paper, it is now done on a computer screen. What I had never seen was this process done in the physical. But I can figure out how…
A laser ray trace table used to demonstrate the focal point of a simple lensTake a few laser line modules, a bit of sheet metal and paint, a bit of circuitry and we can do this!
In the photo you can see the idea… Five red laser line modules are aligned across a table. Stick a lens section in the beams and you can observe refraction as it happens. Using a double convex lens, all of the beams converge to a focus. A clear demonstration of the basic principles of optics!
A DS1013S delay line IC photographed for an eBay saleMy big project over the last month has been cleaning out the garage. Not the easy part either, but going through the pile of electronics parts I have on hand and organizing. Part of that organization is culling out and reducing the pile, a task that must be done every few years. I have repeatedly filled the trash can beside my workbench. Scrapping or simply throwing out some of the accumulated parts and bits. Some stuff is just obsolete, some is well past any sort of reasonable shelf life, some I just do not need anymore.
There is some stuff that could have some value. Components and gear that could be sold, for that stuff there is eBay. I have eight listings active right now, and a few more I need to set up. Much of the stuff is electronic components, ICs and DC-DC converters. I am making some money from this stuff, not a lot, a few hundred dollars so far, perhaps enough to buy a few new toys.
In an age of cost cutting on products to compete in a very competitive market place, some producers seem to go too far. Reducing the quality of the product to the very edge in order to shave a few pennies. One consequence of this has been more battery leaks, with Duracell being by far the worst offender. Seriously, why does anyone still buy Duracell products! This time it was a friend who brought me the latest corrosive disaster, a Wii Balance Board with a mess in the battery compartment.
The battery compartment of a Wii Balance Board after the repairAt least the balance board was easy to get apart, just a mess of screws on the back to remove, a few minutes with a phillips screwdriver. First remove the feet with three screws each, then the backplate with another ten screws. The unit is essentially a fancy bathroom scale with load cells in each foot. Rather nicely made, the engineers did a good job here.
Opening the case reveals the good news and the bad news. Good… The battery compartment is removable with just another couple screws. Bad… The damage here is severe, the small circuit board under the battery compartment is heavily corroded, traces and components destroyed. Good… The complex circuits for the unit, the processor and transmitter, are on another circuit board on the other side of the balance board and are untouched. Bad… The battery contact plating is gone, these are unusable. Even the wiring harness is damaged.
The usual engineering minutia takes up much of my week… Paperwork, documentation, purchase orders, meetings, etc. There are the occasional chances to just have a little electronic fun. Thus I greeted a request from a couple of our support astronomers with some enthusiasm. They needed a variable intensity light source for calibration of the OSIRIS spectrograph. This source sits inside an integrating sphere on the AO bench along with four spectral sources, small tubes of neon, argon, xenon and krypton.
The remote current controller PCB and case prior to final assemblyThere was already a white light source in the calibration sphere, but control was limited to simply on or off. The spectrograph uses various filters that each let through differing amounts of light from the calibration source. This created problems during calibration, some sort of variable intensity source was needed. It also needed to be quite precise, with a well regulated output that would not vary during the hours a calibration script could run.
I set aside a bit of time each day to design and build the source. The last couple hours of the afternoon are best, at this point I have had quite enough paperwork. A chance to practice my trade sketching out the circuit, or simply sitting at the bench and soldering… Perfect.
With an upcoming open house, everyone around the observatory is frantically trying to get everything in place. There will be all manner of science exhibits throughout the observatory headquarters complex. Exhibits about our research, controlling the telescopes, an IR camera display (Get your portrait in IR!), liquid nitrogen ice-cream, just a lot of fun.
A two mirror laser spirograph buildI am coordinating an exhibit we named Optics Lab… As you would expect, most of the exhibits in our area teach basic optics, light, lenses, etc. Understanding light and optics is a basic skill in a large observatory. We will have a few lenses on rails, a laser ray-trace table with acrylic lenses, an exhibit on polarization, and even a simple laser interferometer.
When attempting to teach something, a little eye-candy is helpful to catch the attention of the audience, particularly kids. Our group includes a laser engineer and a laser tech, so the use of lasers was obvious. There is little that catches the eyes of a kid faster than a bright laser beam. One of the first ideas they tossed on the table was a laser spirograph. After a few moments thought the answer was clear… I can build that!
Schematic for the SpiroLaser control PCBTime to dig about in the scrap box! Actually more than a few boxes in my case, I am a bit of an electronics pack rat. A green laser module… Check! Small DC motors… Check! A few voltage regulators… Check! A couple potentiometers… Check! First surface mirrors… Check! In an hour of rummaging about I quickly located everything that was needed.
