Moving heavy equipment with your mind

This book was written in 1922 by an artillery school, and includes lots of info on hoisting and moving huge, heavy, delicate machinery, like cannons or machine tools or overturned/stuck vehicles. The book covers knots, leverage principles, and some of the basic tools that can be created to help the task.

Mostly you will be using manpower and simple leverage multipliers of all kinds, along with some good thinking about what you're doing. Thus the 'mind' part. Unfortunately they don't cover pure telekinesis in this volume; I'm still looking out for that book.



Rotary to linear motion with wooden gears

Build a robust, accurate rotary-to-linear motion transfer box within a weekend, without spending any money.

Some projects need an element that moves in a straight line, but this is not always as easy as getting rotary motion straight from a motor, pedals, or crank.

To accomplish this, I read online about mechanical linkages and selected a hypocycloid linkage. It has a very elegant and simple design, with a long linear travel for a small size. Rotary input (like a hand crank or drill) applied to the central shaft is converted to straight line motion across the diameter of the ring gear. The linear motion will be as long as the ring gear is wide.

I hand-cut two plywood gears on the bandsaw and built a frame to run them in. The ring or internal gear has 32 teeth, the round gear has 16 teeth. Using powers of two ensures both good support from the spirit world, and harmony with the geek nature.

My gears were cut from a paper pattern generated with the free online gear calculator at http://woodgears.ca/gear_cutting/template.html , which I printed out and glued right to the plywood.

According to the site's gear-making recommendations, this is sometimes a problem with laser printers -- though not with inkjets, since they have tighter registration requirements. I used a laser printer and measured the gear patterns in several places to ensure that the laser printer didn't stretch the image in any direction.

All parts were cut by hand on a bandsaw, trimmed by hand (very little) with a wood file, and finished and lubed with paste wax. 1/2" bolts and washers were used throughout.

Since the gears are hand cut, and since this is the first time I have made gears like this, there are small variances despite the saw being quite accurate and maneuverable. The dimensions aren't exactly perfect -- they are very close, however, and well within working tolerances.

I clamped all the various layers and spacers together, rotated the movement by hand and tested the path, tuning with a small hammer to tap the pieces into their best fit.

I aligned the teeth to find a combination that gave smooth travel without binding.
I rubbed some wax into the teeth to ease their meshing up during the initial tests.

Then I chucked up a drill on the main shaft and gave a test run, repeating my tuning process and eventually screwing all the layers together when I was satisfied. I then ran it for a few minutes to work in the gears.

The time spent aligning the parts by hand provided a much better end result -- this was time well spent. I haven't finalized this as a working tool, just a prototype, so it's not painted. But it is sanded smooth and finished on all 6 sides, square, and generally nicely worked.

The gearbox is quite stable, and it goes way faster than I would need. I estimate the main shaft got going at 200-240rpm, at the drill's fastest speed in high gear.

This was a successful project and consumed about 10 hours of time to plan and complete. (This includes the time spent taking the laser printer completely apart due to paper slippage problems, servicing the paper feed rollers, and reassembling it.)

This project was purposefully set up with very rough measurements throughout. I used it to improve my skills at eyeballing, guessing correctly without actually measuring anything, and improvising solutions precisely the first time.

I used a divider to copy one measurement --I needed to rebuild the center arm, but with a 1mm increase in length between the main shaft hole and the gear hole.

Everything else was strictly eyeballed, even measuring the center of the main axis hole was an eyeball measurement. This was probably not the best or easiest choice. But that was the point, to do something using basic hand techniques, and have the project come out working as planned despite the lack of laser cutters, CNC tools, or even exact measurements.

Don't be afraid to extend the boundaries of your ability and sharpen your techniques for making good guesses and improvising in your projects. It improves your work when you have more practice at deciding confidently off the cuff, and fixing as you go.

* Add an adjustable counterweight to the main shaft to counter a minor wobble.
- Apply a more attractive, durable finish like battleship grey spray paint.
- Consider making parts in metal or acrylic. Heavier = more stable.
- Add proper bearings for smoother and faster travel. These could be shop built or salvaged.
- Add a better driver, like a crank or built-in electric motor.


Homemade UV LASERs

This week we decided to build lasers. Not just any laser, but one that puts out 100KW pulses of Ultraviolet light. Okay, the pulses only last 1-2ns and it's hard to burn things with it, but it's still pretty cool. It's pretty easy to make from junk, and it uses Nitrogen right out of the atmosphere to lase. Check out the video:

23B TEA Laser



Venus de Cthulhu

Modified this otherwise unremarkable found-statue:

sorry for the sideways pics, maybe you can turn your monitor.

Tool Blocks and Holders

Pliers holder

This plier holder declutters several drawers of jewelry tools. I used a torch to forge and bend the scrap of rebar. I forged the center bar thinner to allow the smaller pliers with sprung handles to rest nicely alongside their larger cousins.

Handmade fids and awls (plus 2 bought ones)

I made up a few sets of hardwood tool blocks for my ever-growing collection of needle files, assorted bits, awls, and knot-tying fids. They get the tools sorted and visible, as well as helping protect sharp points and delicate files from getting the blood of the unfortunate on them, which rusts the metal.

Sandblasted dinosaurs were added for visual interest.

Salvaged pallet wood with nice nail stains and character.

Open Access Control v1.00

Open Access Control v1.00 system prototype

The Open Access Control system is an electronic alarm and door access system currently in development by Arclight at the 23b Shop. It is open-source and open-hardware, meaning you can get in on the fun and build one yourself.

It is currently being tested for duty as a burglar alarm, door chime, and people tracking system. It logs door access data in syslog format, sends the data via ethernet, and has on-board memory as well for data, command, and user storage. Its real-time clock ensures accurate data logs.

A numeric keypad is attached for entering commands -- for example, make the door open , set to chime on open, stay unlocked for x minutes, lock and allow exit only, deny access to a user, add a user, learn an RFID fob, and so forth. More keypads can be added.

Inexpensive RFID readers allow the system to be deployed without compromising the building's doors, windows, or walls to mount a keypad at the entrance, though this could be done as well.

The strike is a standard electromagnetic building strike; there's no sense messing with such a great and overbuilt piece of hardware.

Homebrewed circuit boards allow fast prototyping

The system is built around an Arduino Duemilanova board with an Ethernet shield and custom hardware for the in/out devices. The boards were designed and built at the shop. Laser-printed PCB images and Fab-In-A-Box transfer resists were used to generate prototypes quickly and easily. An inexpensive ID card laminator applied the resists to the board material. A fast accurate etch was obtained by wiping ferric chloride onto the prepared board, which was a novel method that seemed to work more quickly than tank etching with the same chemical, with much less cleanup and chems used.

The power supply board

Users can build their own unit from scratch, or possibly obtain partial, full, or assembled kits by contacting the shop.

Hardware files and Arduino code are available here:

Users would be able to write code to support other functions of their own devising, like releasing poison gas, activating lasers or tranquilizer dart projectors. Of particular interest are the 'talking sentry', 'MOTD', and time-aware Mini-Bake Oven modules, all in various stages of development.


Open Access Control - Board is done!

In a fit of motivation, I got the PCB etched for the Open Access Control. I used the "Fab in a Box" process from this company and got pretty good results. I didn't have quite enough heat on my toner transfer and ended up having to do some re-work with a Sharpie, but it works.

Check it out:

I got the purple base color by boiling in liquid RIT dye concentrate for about 15 minutes.

Hopefully, the Shop Party this weekend won't keep me from at least getting the components on there over the weekend.



Open Access Control v1.00 Board

So the I finally got around to finishing the circuit and PCB layout for the Open Access Control for Hacker Spaces.

Check it out:

The Arduino code and Eagle CAD files for the hardware are available for download at:

Google Code Page

The current version supports:
-2 Wiegand26 RFID door readers
-4 Output relays (5A)
-4 Alarm zones
-Separate 12V (2) and 5v (1) power buses for sensors
-Opto isolated inputs on everything
-Ethernet board ready

Now to get the PCB etched, stuffed, debugged, tested...What could be simpler?



Ruben's Tube

On a whim, I decided to build a Standing Wave Flame Tube, also known as a Ruben's Tube.
I used 1.55m of 4" diameter ABS plastic pipe, capped on one end with a rubber plug and fitted with a machined plastic adapter to accept a speaker on the other. Our first attempt (using a 4" speaker and a PA amplifier) resulted in accidentally blowing out the speaker, so we decided to try a set of Dell PC speakers. This worked out pretty well, as we could hear the sound in addition to seeing it.

Here is it with a pure 252Hz source. Note the nodes and anti-nodes. We used 55x #50 holes, spaced at 1" apart. The top of the tube is covered with Aluminized tape to keep the plastic from melting. Note that this thing flows quite a bit of gas - from what I've read, the total flow rate is determined by the Bernouli principal, and stays at the same average regardless of what is going on with the standing waves.

It appears that it was able to flow several liters per minute, as it had no problem freezing a small 4x16" propane bottle.

The Windows function generator software we used was this:

Marchand Function Generator Lite

The tube responds nicely to music as well, but it is very sensitive to any kind of wind.

A future experiment will be to measure the speed of sound of the flammable gas.



Arduino I/O Shield Project

After trying out a new do-it-yourself PCB fabrication process, we finally have success with the Arduino shield I had been working on. This prototype has:

-2 buttons for input
-2PWM outputs with power MOSFETs
-7-segment display for status

This will be the new test platform for programmed operation of motors, high-powered LEDs, etc.

Check it out!



Droid camera + low light = scary shop night scene

I've discovered that the welding booth lights, microscope, and a few other small light sources can turn the shop into a nice, cave-like environment for coding or studying or whatever.

Here are a couple of scary pictures I got with the 5mp camera on my Droid phone.

Welding booth (red UV curtains):

It seems like the less light you have, the more bizarrely these little camera react.

Now I'll have to get the tripod out and see what happens when there's no shake, and the flash is disabled.


Electro Etch is GO

This article describes my homebuilt AC/DC electro etching device. It's built from plans I got online -- I got the original plans from http://www.knives.mlogiudice.com/knifeshop/etcher/index.shtml . During the design phase, this site was the most helpful for the hardware building. I now know I can go ahead and use any basic power supply design pretty easily, so the next one will surely be a circuit of my own design.

The etcher is mounted in an aluminum case salvaged from a parallel printer sharing switch from the 1980s.

This is the second build of this circuit that I have done. This one has a much better case and a larger capacity transformer than the first, but the components are all salvaged from the first build except for the case and transformer. Total cost was <$30 -- it's only that high because I bought almost everything new the first time around. Just about any power supply will do -- I have used a wall wart transformer with the plug cut off and a couple of alligator clips soldered on to do etching and plating. Stick to lower voltages like 6-24v for sharper results, since the image tends to bloom with higher voltage for longer time. Make sure you get the biggest current rated tramsformer you can, since this circuit can easily put out over 1000 mA of current through your workpiece and a smaller transformer will definitely overheat or short out in an exciting manner. I would recommend looking for at least 1 amp output to avoid overheating.

The plans at http://www.knives.mlogiudice.com/knifeshop/etcher/index.shtml are abundant with parts list, schematic, etc.

Here's a link direct to the schematic: http://www.knives.mlogiudice.com/knifeshop/etcher/electro-etcher_circuit.pdf


Safety glasses on! The first time you start the circuit you risk finding accidental short circuits and bad solder joints, defective components, etc. Please protect your precious eyes so you can keep having fun.

Use your hand (or go to Harbor Freight for a $10 IR thermometer, for safety) to check how warm your components are when you power up for the first time. Check every few minutes on the heat level of the transformer, bridge rectifier, and other heat-generating power components. After it's running stable, you can thus be confident that your circuit runs in a known manner.


For stencils I have used all different things like electrical tape and contact paper; anything electrically insulative will work. Draw your design with a Sharpie or paint pen (or a graphite pencil) and cut ewith a utility or craft knife. You can also cut with stencils or punches; I used a tiny round punch to make dot matrix letters and it worked fine.
You can even paint on the surface or use asphaltum, wax, or almost anything resistive. See a printmaking book for further suggestions.

Currently I have stencil paper that starts out completely insulative, but turns conductive where it's written, typed, or stamped. It's a fine plastic mesh ribbon with blue waxy emulsion which you push out when you impress the ribbon. Thanks to a friend with contacts in the marking industry, I got this for free because they ordered the wrong material.

You can get (or better, make) steel stamps made of your logo or words, for stamping straight onto the stencil paper. The mint box was done this way, using a CNC milled 23b Shop logo as the stamp. (I actually burnished it with the flat of a Sharpie; I didn't stamp it because it is a large and thin milling.)

The stamp doesn't need to be hardened like a metal-marking stamp does, since you are just stamping the paper on a soft wood or plastic surface -- you can use wood or plastic for this kind of stamp, or a piece of softer metal like copper. You could even electro-etch a plate and burnish it into the stencil paper.

Note that a greater exposed surface area of your stencil will mean a slower etch. Same with a larger probe.

Storebought electrolyte solution is probably more effective, but I have table salt and baking soda to work with at the moment, and they both provide good results.

Starting with oil-free metal is a must. Otherwise the oil will insulate parts of your design and ruin the line quality. This means scrub with #0000 steel wool and a bit of dish soap, or use another degreaser of your choice. You can sandblast it as well -- this removes the oil plus a bit of metal, leaving a satiny finish to contrast the smooth melty appearance of electroetching.

Salt water electrolyte rusts metal very quickly, so rinse and brush finished work well and dry thoroughly with forced air, a warm sunny spot, or a heat gun or hair dryer. Apply oil or WD-40 right away.


You can probably use any fabric to protect the probe surface from direct contact. I've used t-shirt fabric and synthetic felt to good effect.

I have made several probes
with stainless welding rod for the conductor and brazing or welding a banana clip lead on, then sliding into a plastic hollow rod for a handle and taping, wedging, or gluing it in place. Favorite shape so far is a hockey stick with about a 3 inch exposed conductor, bent at 60 degrees or so, 1 inch down from the plastic handle. This allows wiping across a roughly 2" swath, or leaving it in place to etch a small design.

I also made a probe from a circle of heavy stainless screen, a few layers of t-shirt material, and a 4" PVC pipe cap. It's used for longer duration etches, flat plates, and larger designs. Wired it all together with a bit of stainless wire and clipped a banana jack into the inside. I can set the probe on a workpiece with the pad downward, and pour electrolyte into the cup shape. This trickles through and collects in a plastic dripcatcher pan, so the electrolyte stays really fresh and the current stays high. It can then be recycled until the current drops too low. This design is win.

A spot probe with a stainless mesh and a felt pad, all on the end of a 3/4" or 1" plastic dowel, will come next.


The workpiece is attached to the positive terminal with a spring clip or wire hook. Stainless steel or titanium are best if the piece is to be immersed in electrolyte. No copper should be exposed to the electrolyte anywhere, or else you risk polluting your solution and plating your workpiece or probe.

The probe is at a negative voltage to the workpiece during DC operation -- so clip the probe on the negative or ground of your output terminals, and the workpiece to the +12 or +5 side. The metal from the workpiece migrates toward the negative terminal, is my understanding.

Avoid touching the probe's metal to the workpiece directly; this maximizes current and minimizes electro-etching action, heating your circuit and possibly shorting components.

You can clean the probe off when it gets gunked up by reversing the voltage and DC-etching the probe; the cruft will collect on your sacrificial workpiece. This is also the basis of a larger electrical de-ruster; plans and pics of our 35 gallon de-rusting device to follow.

I am going to be adding a voltmeter / milliammeter to avoid having DMMs clipped in all over the place, but it runs stable and cool at 10.5VDC out sending about 500mA through the circuit.

Also making more smaller spot probes would be nice, for doing a small touchmark or logo on a tool or knife handle.

I'll be soldering the whole thing permanently together and removing most or all of the spade connectors.

awesome workbench!

Today's workbench of renown is at Willie's Shoes in L.A.
Check the video and enjoy a lot of really amazing old leatherworking tools, amazing historical photos of celebs who've gotten shoes from Willie, and some very nice industrial sewing machines. These tools are old and worn, but they allow craftsmen to create beautiful, useful, and satisfying work because they're just right.



Making PCBs at home - Part 2

The quest for the perfect "fab at home" PCB solution continues. This week, we started playing around with "Direct PCB Printing" for making printed circuit boards (PCBs).

First, here is a quick recap on how to make PCBs at home.

To start with off, you need a layout. I'm currently designing the schematic and PCB layout with Eagle Cad and either outputting image files in monochrome or printing directly from the program. Exporting the images has the advantage that I can put multiple PCBs onto one board or page to save materials. Printing directly from the program is simpler.

Once I have the artwork, I fab the board and drill using a Dremel-brand micro drill press and carbide PCB drills. We buy resharpened carbide PCB drills on eBay. Common sizes are #52-#70. For best results, get a pair of dial calipers and mic the pins on any through-hole components you will be using.

For the fab part, there are basically 3 methods that are practical to do at home:

1. Photo resist:
Laser or inkjet print to transparency paper, expose your image onto a pre-sensitized PCB board (you generally buy them this way), develop, etch. You can buy these from Mouser, Digikey, or your local electronics store.

Advantages: Tried and true method, good resolution.
Disadvantges: Messy, need glass exposure frame and bright sun or a UV light, extra chemicals involved. Double-sided boards are possible but you need to line the images up carefully before exposure.

2. Toner transfer:
Laser print or photocopy your image to Press-n-peel or specific types of glossy paper stock, then iron the image on to your bare copper PCB. Any PCB stock will do, but it must be cleaned with sandpaper and degreased with acetone before applying the transfer. Remove the paper by
soaking in water, tocuh up any bare spots, etch. Works best if you use a laminator or a very hot iron.

Advantages: Cheap, easy, moderate resolution. No chemical needed other than etching solution. Double-sided is easy - you can drill some of the holes after you transfer the pattern for the first side, making it super easy to line up the second side artwork on a light table.

Disadvantages: Can leave pinholes or bare spots that need touching up, paper can be hard to remove. A new 2-step kit called "Fab-in-a-Box" is supposed to address this. I just ordered it, so I will let y'all know how it works when I'm done testing. Works best with medium sized (i.e. 16mil+) traces.

3. Inkjet PCB printing:

This is the new up-and-comer. The basic process involves either printing
on a modified Epson inkjet, or using a stock model that accepts CD-ROMs
and a special adapter. You clean the board like you would for toner
transfer, load it into the printer, and let it do it's thing.

A special refill ink called "MIS PRO Yellow" is typically loaded in
one of those aftermarket refill cartridges. Once printed, the board
is "cured" by heating the ink on a hot plate, and, depending on the
results you are getting, sometimes a second coat is printed and cured.
Etching is the same as above.

In another variation, some toner or powder-coat is dusted onto the wet ink
before cooking. This results in a very strong coating with one pass.

Advantages: Amazing resolution. 8mil traces are possible, although I've
only done 10mil so far. Clean and neat, and misprinted or smudged boards
can be re-used by wiping off the ink with acetone.

Disadvantages: Can only print specific sizes (the adapter I have in mine
does 3.5x2.5" boards at 1/32" thick). Larger boards require modifying the
printer extensively, and attaching a tape leader to feed the board.
Process is a little fiddly and you have to play with the margins, ink
settings, etc for good results.

So far, the results are promising. We bought the kit from Full Spectrum Engineering and then set about finding a suitable inkjet printer. Fortunately for us, there is a Goodwill Industries computer center nearby. For $15, I picked up an Epson R200. This printer has two properties that we need:

1. It accepts CD-ROMs (the boards we use fit into a CD tray adapter)
2. It has an piezo-electric print head that will run a variety of inks.

Ours was missing the CD tray, but it turns out that these are available all day on eBay for around $10. Next, we needed a blank ink cartridge and a bottle of Yellow MIS-PRO ink. We also needed a way to reset the empty cartridges so that the printer will actually try to print.

For about $30, we found all of the necessary supplies at Ink Supply, including a chip resetter tool, a self-resetting empty cartridge, and the ink.

After lining up the adapter in the tray and taping it on, cleaning the 2.5x2.5" PCB blanks with 320 grit sandpaper and acetone, we ran some boards. The first one was less than spectacular, as I failed to read the directions and only ran one coat, then failed to cure at a high enough temperature. The best result (board #4) was obtained by running a pass of MIS-Pro ink, then dusting with power coat powder and heat curing. This created a very solid resist with clearly visible 10mil traces. Photo is below:

And here is the original art work:

So there is still more work to do, but I think this one may be a winner.



Balloon project - Designing a GPS Board

We made more progress on the balloon tracking electronics this weekend. We tested out the Big Red Bee tracking transmitter and made an insulated, ruggedized package for it.

Fore the GPS-based tracker, we have settled on the Byonics Tiny Track 4 APRS system. Since many GPS units do not function above 60,000 feet elevation, we are going with the special "High Altitude Build" of the Inventek ISM300 GPS module.

This unit only comes as a tiny SMD module, so we are integrating the unit, a 25mm active-patch antenna, a MAX2323 driver IC, a backup battery, and assorted other bits into a custom circuit board. Here is the prototype so far:

The board is also almost reach to etch. I found a good Eagle Cad tutorial on making ground planes, and refined the design a bit:

The 2.0 version will probably be all SMD components, but this should get us going, as we have the through-hole versions of all of these parts on hand at the shop.


Shop Day Today!

We will be having another open shop day today from 3:00pm onwards. We will be working on the flight systems and tracking beacons for the high altitude balloon and doign some home breeing. Food will also be served.

Come on down, and bring your projects!



RFID Acces Control - UPS Prototype

This week, we made more progress on the Open Source RFID Access Control project. The 5A power supply with UPS and battery charger has been prototyped (using another toner-transfer resist board) and is undergoing testing.

Check out:

And the board:


Balloon Launch Video

Here is a video of the balloon launch:

20gm payload balloon launch

High Altitude Balloon project

So we've started a new project at the shop: a high altitude balloon. This started when we acquired an 80ft^3 Helium tank when we bought out at an estate full of old tools and supplies. The eventual goal would be to be able to send a package of instruments and a camera up to 100,000' and recover it at will. Rather than risk $100s in electronics right off the bat, we've decided to use a "progressive" approach to gain experience and test systems. Here is what we've done so far:

1. The $1 flight: We bought some 17" "jumbo" party balloons from the balloon wholesaler down the street. (Funtastic on Lemon/Raymond). Some testing shows that this balloon will burst at 24-25" and has a gross lift of just over 35gm. Based on this, we flew one with 22.5gm of payload (sand) and got around 150m/min in climb (estimated). Using the balloon burst calculator, we estimate that this balloon could go to 20-25K feet.

Status: Successful

2. The $10 flight: We launched the same balloon, but added the following:

  • A parachute of 20cm, made from a black trash bag, some 6lb test fishing line and a bit of Scotch tape and a fishing swivel.
  • A small radio beacon, made from leftover parts. Used a 23A battery and a 6" piece of 30ga wire for the antenna. We had trouble getting it to oscillate with a bigger antenna attached, probably due to capacitance issues.
  • 3m of 10lb test fishing line to hold it all together.
  • A 10K thermistor from Sparkfun.com, to change the beacon's tone in response to temperature.
This package got flown last weekend in the Mojave desert. What we learned:

1. This balloon/weight combination has plenty of lift to send the package much farther away than you can see even with binoculars.
2. The tiny radio transmitter, with its inefficient antenna and <20mw output could not be tracked after about 30seconds, even with a good directional antenna and receiver.
3. The white styrofoam package with clear tape and the black 'chute were very visible, even at several miles.
4. Testing the parachute from the roof of the shop shows that it deploys 100% of the time. 60gm of weight could be brought down nicely with a 30cm chute.

We did not get this package back, due to the wind picking up and sending it over a mountain.

Status: Partially successful



Laser Printed Masks for 2-Sided Circuit Boards

Printing on glossy inkjet paper -- 20 cents per sheet -- and ironing the paper onto a clean PB gives an almost perfect transfer of the mirror image as an insulative mask against ferric chloride etching. (I have read that magazine paper also works -- experiment with any claycoated paper or cover stock.

Don't use steel wool to scrub your board, it leaves little scraps that can interfere with etching as they rust. Scotchbrite seems a good solution instead, being nonmetallic. You're scrubbing to degrease so a shot of vinegar or alcohol would help. Wear gloves. Scrub everything bright.

Arclight suggests setting the iron to NUCLEAR for the ironing step. Line up your paper (extra registration steps required for 2-sided boards) and tape it on, then fold back the paper. Preheat the board 30 sec with the iron, flap the paper back, and iron firmly.

Let cool, then soak in water to remove the paper. Pull or roll it off gently at first to make sure it's transferred, which it should be, and rub with a finger to get any excess pulp off. (It shouldn't be too delicate after cooling.)

After mask application, go over it with a nice fresh Sharpie or other resist pen or tool to perform any mask touchup or fix any dropout spots.

Soak the board upside-down a few minutes in warm ferric chloride etching solution. Do this on paper, in the dirty side of the shop, with nitrile gloves and a nonmetallic tray and tools. FC eats all kinds of metals, including your aluminum camera and laptop, it stains absolutely everything -- skin, cloth, tile, cement, metal, etc -- and it is a real stinking mess if you spill it.

Remove the board and neutralize any excess FC with baking soda, then rinse in cold water. Baking soda is a shop staple for many reasons as well as neutralizing acids and removing funky odors from the shop fridge.

That's all that's required to make totally serviceable 2-sided boards.


Reverse Geocache

A while back, a friend of ours asked if we could build one these for him:

Reverse Geocache Puzzle Box

Since I like a challenge, I went for it. I ended up using the EM-406A GPS module from U.S. Globalsat, a standard Arduino 328 board, a backlit 16x2 character display from Futurlec.com, and the Pololu soft power switch from Sparkfun.com. The code will be cleaned up and posted soon.

Here are some pics of the build and completed project:

Initial board:

Open Access Control - Power Board with UPS

Thanks to Martin Wood from the hackerspaces.org mailing list, we have a v1.0 circuit for the UPS/Power supply board. I decided to break this out into a separate board so that it is optional. The basic circuit floats a 12V sealed lead acid battery at around 13.5V, and uses this as the regulated output for sensors and door locks.

Also, it looks like MOVs (metal oxide varistors) are the way to go for clamping the voltage spikes from a door-holding magnet.


Shop Party 4/17 - 4/18

With no layerone this year and a powerful urge for some defcon warmup, we're
going to throw a giant birthday party for Amber who recently moved out of Utah! It's at the 23b shop, there will be TWO POOLS and a CAKE FIGHT.

Bring: girls, booze, fun, swimsuit, stuff to work on at the shop

Invite: Everyone

Pump up: the volume

Sat April 17th, any time (people should be there friday 8pm to sunday 6pm)
no drunk driving! Everyone is welcome to sleep at the shop, bring a pillow/blanket though.

418 E Commonwealth Ave
Fullerton, CA 92832



Open Access Control - Code

The code and v1.0 Eagle file has been posted to Google Code. Check out:


Open Access Control v1.0

The hardware design for the Open Access Control for Hacker Spaces is nearly done.
This system uses the Arduino Duemilanova board with Atmega 328, and provides:

-Shield compatible with Arduino
-DS1307 Real-time clock with battery backup
-(2) Wiegand26 reader inputs (optoisolated)
-(4) Alarm zone monitor ports using Analog0..3 (optoisolated)
-(4) Relay outputs, rated to 10A/220VAC
-Spare pins 10..13 to enable Ethernet shield use
-Built in 12V unregulated, 5V regulated, 12V regulated supplies for alarm sensors, door hardware
-Built in UPS (smart charger in next design)
-Separate fuse protection for everything

Check out: