LiPo Battery Ruggedized Power Module

A while back, we decided that we needed a 24v power source for various “testing” applications. This source needed to be durable enough for daily use by a wide variety of people without becoming damaged. It also needed to protect the device being powered, and be easy to maintain.

Given that tall list, Ben suggested a HobbyKing LiPo pack, 6S, 5Ah. With that start, we decided that it should have volt and amp meters for monitoring, as well as a circuit breaker to provide positive power disconnect, and protect the battery (easily capable of 150A into a dead short).Meters were ordered from Ebay and the breaker was something out of an old UPS.

The blue enclosure is a waterproof storage box from Walmart, modified to pass through various connectors.  It’s not waterproof at this point, but we’re more after the durability of the polycarbonate than the waterproof aspect anyhow.

Internally, there’s quite a bit going on.  The battery is packed into a foamed-off area, while the other side contains the electronics, including the circuit breaker,ammeter shunt and all the connectors.

Charging is accomplished via a modified ATX connector (which re-presents the balance plug and main power leads), with a fuse to protect against abuse. The idea is that it’s virtually impossible to charge the battery improperly, or to break a relatively fragile balance connector.

Overall, it was a pretty straight-forward build, and cost around $90, including the battery and all the connectors.

Omaha Creative Week Spark Event – Tuesday September 4th, 7pm.

Just a reminder, the Omaha Maker Group’s regular meeting on Tuesday, September 4th is an Omaha Creative Week Spark Event. We have several presentations on the docket, including a summary of the Omaha Maker Group (and Making as a whole), as well as a hands-on presentation on manipulating your car’s onboard computer for diagnostics and customization.

Hope to see everyone there!  If you have questions, don’t hesitate to email info@omahamakergroup.org.

Straw Tower Contest – Results

As part of the recent OMGWTFBBQ festivities9, a contest was held, pitting the forces of gravity against the weight of cold hard cash (pennies, to be specific).  The goal of the contest was to use soda straws to support as much currency as possible in as high of a position as possible, thus racking up the most “inch-cents” of score.

As it turns out, we ended up going to “foot-dollars” and using weights that weren’t exactly copper, given the engineering of some of the entries. Check out the results below.

Team Inches Cents Inch-Cents Foot-Dollars
Brandon 8.25 2898 23908.5 19.92
Stephanie & Cait 8.25 2898 23908.5 19.92
John & Don 11.25 271.5 3054.38 2.55
Claire & Dad 7.5 271.5 2036.25 1.70
Jess & Company 14.25 45 641.25 0.53
Patrick & Travis 19.375 14 271.25 0.23
Ben & Dave 11.5 0 0 0

KC Maker Faire 2012

This past weekend, Dave and Eric and I met up with quite a few Omaha Maker Group members at the KC Maker Faire, and had a blast.  We were initially going to have a booth to show off the awesome projects from around the Makery, but had far more people who wanted to go See the Faire instead of Work At the Faire.  Somehow, this change was miscommunicated to the Powers that Be, and we ended up with a booth and sign anyhow (notably unmanned).

We definitely got to see some neat stuff, including one of those optical-resin based 3D printers. ArcAttack was pretty awesome as well, if amazingly loud.

Beyond that,  it was an excellent a venue to share ideas… Looking through my pictures, I think Eric and I had identified at least 3 or 4 projects we want to try, and dozens of smaller ideas.  I saw a few 3d printer innovations, a “bubble printer” (by ArchReactor),  a portable whiteboard cart (For the Makery, at Hammerspace); We also a “waterflow table” (aka a Sluice Box) at Science City, where it pumps water down a trough, and you insert dividers to change the flow paths.  It seems pretty trivial, but would be one of those “fun to mess with” sorts of things.

I was a bit surprised that there wasn’t more merchandise (specifically Arduino kits and whatnot), although I’m not sure that this was a bad thing, in retrospect.

 Overall? Probably one of the more amazing Making experiences I’ve had. I got to see neat things, talk to interesting people and generally have a good time with friends, old and new.
I’ll be back next year, and would seriously consider making the trek to one of the larger Faires on the coasts.

Egg Drop Contest – Results

Last Sunday (April 1st) was the first Omaha Maker Group Egg Drop.  The competition was much in the same style as the Nerf Gun Mod Contest run last fall; This competition had a lower entry barrier, and thus far greater turnout, with 10 total entries (Eric entered twice).  All the eggs survived the drop, but Stephanie was the big winner, with a score that bested the next entrant by a factor of 4. Click through for full results, and a little high-speed video, thanks to Ben. Continue reading

Microscope Photography – Integrated Circuits

On Tuesday night, we were disassembling some old printers, and salvaged some large ROM chips. Patrick got the idea to use the mill to remove the top layer of the case, and expose the IC inside.  Here are some photos we took of the chip’s insides with a microscope. Magnifications range between 4x and 40x, thought the 40x were pretty difficult to illuminate properly, because the lens obscures most of the light. As for the cameras, we  used a little point and shoot and a cell phone camera, both just held up to the microscope’s eyepiece.

Contacting the International Space Station

Last Wednesday, OMG member Pat Joseph (KØCTU) stopped by the Makery to see if we could make contact with the International Space Station, as it passed overhead.

The Space Station has a few amateur radio operations on board, and the one we were making contacts with was an automatic mode known as APRS. The automated station heard my transmission and sent back an acknowledgement three times during the pass.

About a  half-dozen people took part in the attempt.  James and Rick manned the antenna, while Pat ran the radio.  The rest of us provided moral support :)

The antenna that Pat brought down was pretty innovative. The main body was made from plastic conduit, and the elements were built from bits of metal tape measure.  The result is a quick-setting antenna that is difficult to damage, yet easy to fold up and store.

 

What is this “Variac” Thing?

A Variac (also known as an Autotransformer) is a variable transformer, which allows the user a convenient way to control the power to an AC appliance.  In our context, it’s typically used to adjust the output of a heating device. The variac currently at the Makery is a 20-amp model manufactured by PowerStat.  We’ve configured it to scale voltage only in the down direction, so that the output range is 0-110vac (or whatever line voltage happens to be).  The transformer is outfitted with standard AC outlet fittings, and is mounted to a board for easy transport.  It should be noted that this transformer is NOT isolated, so the output could still be hazardous, regardless of how low the voltage happens to be set.  As with most other equipment, the variac is stored in the TOOLS cabinet.

Easier Vacuforming with Sintra

One of the other projects enhanced by the Variac is the vacuformer.  It consists of two parts: a box with a heating element that melts plastic (background) and a perforated box which sucks the softened plastic down over a heat-resistant form (foreground).  Prior to the Variac, we’d had problems damaging the plastic sheet, because it was heated too rapidly.  Now, we can adjust the heat very precisely and results are much better.

Note: The reason for the incomplete formations in the black plastic (Sintra) is that both the objects used as forms were heavy, metal and cold; The plastic cooled too rapidly, before a good impression could be achieved.

The vacuforming equipment (both the heater box and vacuum bed) are stored in the “TOOLS” cabinet.  There are several shop vacs to be had, typically stored below one of the benches in the “less clean” area.

Acrylic Bender

The Makery’s recent acquisition of a Variac has rekindled interest in a few projects that had been on hold.  One of those projects was the Acrylic Bender that James had been working on. At it’s core, the bender is just a halogen bulb between two aluminum tubes full of circulating water. The idea is to create a line of focused heat to allow plastics to be bent accurately.  We found that it works equally well for acrylic and Sintra (Foamed PVC).  The Bender (along with the Variac) is currently stored in the “TOOLS” cabinet.