Turning The Makerbot Into A Tattoo Machine

April 3, 2014 by 24 Comments

tattoo

ENSCI les Ateliers, the famous design school in Paris, had a “Public Domain Remix” and hackathon recently, with teams splitting up to remix public domain and other free-to-use IP in projects. Most of the teams came up with similar ideas, but one team went above and beyond the call of duty; they turned a 3D printer into a tattoo machine, capable of inking a real, live human test subject.

The build began by plotting a circle with a pen onto a piece of paper. This evolved into printing a tool holder for a tattoo machine graciously provided by an amateur tattoo artist. Tests with “artificial skin” (any one care to hazard a guess at what that is?) were promising, and the team moved on to a human guinea pig.

The biggest problem the team faced is that humans aren’t flat. They tried a few tricks to tighten the skin around the area to be tattooed – metal rings, elastics, and finally the inner tube from a scooter. In the end, the team was able to tattoo a small circle on the forearm of the test subject.

It’s an extremely simple and small tattoo, and scaling this build up to a sleeve would be difficult. A better solution would be to create a point cloud of an arm before going for a much larger tattoo.

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Fail Of The Week: CPLDs That Release Blue Smoke

April 3, 2014 by 17 Comments

The card you see above is a floppy drive emulator for Macintosh. [Steve Chamberlain] has been hand assembling these and selling them in small runs, but is troubled by about a 4% burn-out rate for the CPLD which has the red ‘X’ on it. He settled into figure out what exactly is leading to this and it’s a real head-scratcher.

He does a very good job of trouble-shooting, starting with a list of all the possible things he thinks could be causing this: defective part, bad PCB, bad uC firmware, damage during assembly, solder short, tolerance issues, over-voltage on the DB connector, or bad VHDL design. He methodically eliminates these, first by swapping out the part and observing the exact same failure (pretty much eliminates assembly, solder short, etc.), then by measuring and scoping around the card.

The fascinating read doesn’t stop with the article. Make sure you work your way through the comments thread. [Steve] thinks he’s eliminated the idea of bad microcontroller code causing damage. He considers putting in-line resistors on the DB connector but we wonder if clamping diodes wouldn’t be a better choice (at least for testing purposes)? This begs the question, why is he observing a higher voltage on those I/O lines during power-up? As always, we want to hear your constructive comments below.

2013-09-05-Hackaday-Fail-tips-tileFail of the Week is a Hackaday column which runs every Wednesday. Help keep the fun rolling by writing about your past failures and sending us a link to the story — or sending in links to fail write ups you find in your Internet travels.

Peltier Mini-Fridge Preserves Chip Quik, Marriage

April 3, 2014 by 48 Comments

[Charles] uses Chip Quik to solder his SMD parts, and that stuff can keep for more than six months if it’s kept cool. His wife banned all non-food items from their refrigerator, so he had to think fast and came up with this Peltier effect Chip Quik cooler.

He first looked into that man cave essential, the mini-fridge, but they’re too expensive and use too much power. [Charles] got a nice wooden box from a hobby store and some reflective insulation from Lowe’s. He first tried using a couple of heat sinks but they weren’t going to cool things down enough. Once he got a Peltier cooling kit, he was in business. The temperature in his workshop averages 80°F, and he says the box gets down to 58°F. This is cold enough to keep his paste fresh.

[Charles] plans to use a PC power supply in the future rather than his bench supply. He estimates that his Peltier cooler uses 25-50% of the power that a mini-fridge would, and now his wife won’t overheat. Many great things can be accomplished with the Peltier effect from air conditioning to sous-vide cooking to LED rings. What have you used it for?

Tearing Down A Cheap External USB Battery

April 3, 2014 by 55 Comments

[cpldcpu] recently received an external USB battery as a promotional gift and thought it would be a good idea to tear it down to see its insides. At first glance, he could see that the device included a USB micro-b socket used as a 5V input (for charging), a USB-A socket for 5V output, a blue LED to indicate active power out and a red one to indicate charging.

Opening the case revealed that most space was taken up by a 2600mAH ICR18650 Li-Ion battery, connected to a tiny PCB. A close inspection and a little googling allowed [cpldcpu] to identify the main components of the latter: a battery mangement IC, a 2A boost converter, a 3A Schottky diode, a few 2A N-Mosfets, a 300mA 2.5V LDO and an unknown 6-pin IC. It is very interesting to learn that every last one of these components seems to be sourced from China, which may explain why this USB battery is given for free. Do you think they designed it in-house and outsourced the manufacturing, or is this a product Digi-Key simply bought and put their name on?

Editorial Note: Digi-Key is an advertiser on Hackaday but this post is not part of that sponsorship. Hackaday does not post sponsored content.

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The Tiny, Awesome Class D Amp

April 3, 2014 by 21 Comments

ClassD

In one of [Hans Peter]’s many idle browsing sessions at a manufacturer’s website, he came across a very cool chip – a 10 Watt class D amplifier chip. After the sample order arrived, he quickly put this chip in a box and forgot about it. A year or so later, he was asked to construct a portable boom box kit for a festival. Time to break out that chip and make a small amplifier, it seems.

The chip in question – a Maxim MAX9768 – is a tiny chip, a 24-pin TQFP with 1mm pitch. Hard to solder freehand, but this chip does have a few cool features. It’s a filterless design, very easy to implement, and perfect for the mono boombox project he was working on. A simple, seven component circuit was laid out on a breadboard and [Hans] got this chip up and running.

For the festival, a breadboarded circuit wouldn’t do. He needed a better solution, something built on a PCB that would work well as a kit. The requirements included the MAX9768 chip, a guitar preamp, stereo to mono summing, and through-hole parts for easy soldering. The completed board ended up being extremely small – 33.6mm by 22.5mm – and works really great.

After the festival, [Hans] found a 20 Watt chip and designed an all-SMD version of the board. Just the thing if you ever want to stuff a tiny amplifier into a crevice of a project.

Arduino Controlled Dahlander Motor Switch

April 2, 2014 by 15 Comments

 

Dahlander Switch

[Jean-Noel] is fixing a broken Lurem woodworking machine. This machine uses a three-phase Dahlander motor, which has three operation modes: stop, half speed, and full speed. The motor uses a special mechanical switch to select the operating mode. Unfortunately, the mechanical bits inside the switch were broken, and the motor couldn’t be turned on.

To solve the problem without sourcing a new switch, [Jean-Noel] built his own Arduino based Dahlander switch. This consists of three relays that select the wiring configuration for each speed mode. There’s also a button to toggle settings, and two lamps to show what mode the motor is currently in.

The Arduino runs a finite-state machine (FSM), ensuring that the device transitions through the modes in the correct order. This is quite important, since the motor could be damaged if certain restrictions aren’t followed. The state machine graph was generated using Fizzim, a free tool that generates not only FSM graphs, but also Verilog and VHDL code for the machines.

The final product is housed in a DIN rail case, which allows it to be securely mounted along with the rest of the wiring. The detailed write-up on this project explains all the details of the motor, and the challenges of building this replacement switch.

Happiness Is Just A Flaming Oxy-Fuel Torch Away

April 2, 2014 by 13 Comments

The Egg-Bot is pretty awesome, we must say. But if you have one, you end up with lot of delicate, round things rolling around your abode and getting underfoot. Warmer weather is just around the corner, so segue from spring gaiety to hot fun in the summertime with the MarshMallowMatic kit from [Evil Mad Scientist].

The MarshMallowMatic is a CNC oxy-fuel precision marshmallow toaster based on the Ostrich Egg-Bot design. Constructed from flame-retardant plywood, it is sure to add an element of delicious danger to children’s birthday parties and weekend wingdings alike. You don’t have to get too specific with those BYOM invitations because this bad boy will torch standard and jumbo marshmallows like a boss.

The kit includes a 5000°F oxy-fuel torch and a 20 ft³ oxygen tank, but the tank comes empty and you’ll have to supply your own propane, acetylene,  or hydrogen. It comes with adapters to fit disposable propane and MAPP cylinders, which are also not included. However, you will receive a fine selection of sample marshmallows to get you started. Watch the MarshMallowMatic fire up some happiness after the break. You could toast a special message and load it into this face-tracking confectionery cannon to show how much you care.

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