Solder Fume Extractor With Heat Recovery


When snow covers the landscape outside, you do your best to preserve the heat inside. [Tom] came up with a smart design for a solder fume extractor that includes a heat recovery ventilator. He created a housing which contains input and output sections. A fan is used to bring in outside air, passing it through a heat exchanger made of alternating panels of coroplast. (See diagrams of his setup after the break) This is really a simple design, and could be built in a couple of hours.

A little digging turns up some good information on making a heat exchanger like this one. [Tom] doesn’t mention the indoor temperature, so it’s difficult to calculate the efficiency he’s getting out of it. Apparently they can attain up to 70% heat transfer, depending on the size of the heat exchanger.

In the video, [Tom] mentions some obvious improvements that could be made, including more efficient fans, and a better housing that allows the core to be removed for cleaning. Still, this is a simple setup that provides a good proof of concept. Perhaps we’ll get to see a more permanent installation from [Tom] in the future.

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A Touch Scroll Wheel via OpenSCAD


Recent experiments with the Arduino CapSense library led [Bryan] around the Internet looking for interesting applications. He hit upon a very cool touch scroll wheel made entirely with PCB traces, but the geometry – three interleaved zig zags is impossible to build in the decidedly ungeometric Eagle PCB package. One thing leads to another and now [Bryan] has a cap touch wheel Eagle part designed entirely in OpenSCAD.

The touch scroll wheel implementation [Bryan] found came from an ST touch controller datasheet and used oddly-shaped patterns to create a capacities sensor. Eagle is terrible for designing anything that isn’t laid out at a 45 degree angle, so he fired up OpenSCAD to draw these triangles. Importing into Eagle was another challenge, but a quick Ruby script to convert a DXF file into a set of coordinates for Eagle’s POLYGON command made everything very easy.

If OpenSCADing touch sensors isn’t your thing, there’s also an Eagle library full of them - something we found last week.

Hackaday Links: December 8, 2013


Let’s start off with some high voltage. Here’s a sweet Jacob’s Ladder build from [Robert]. The site hosting his short writeup has been up and down for us so here’s a cache link.

Speaking of high voltage, if you want to switch mains with your project [Tom] has a breakout board for cheap mechanical relays. [via Dangerous Prototypes]

[Dario] made his own version of an electronic Advent calendar [translated]. There are no numbers, you must solve the mystery of the flashing LEDs to figure out which package goes with each day.

If you ever work with lighted arcade buttons here’s a guide for swapping out the light for an RGB LED. This hack uses through-hole LEDs. We’ve actually seen a surface mount hack that includes a PCB to mimic the old bulbs.

Next time you stay overnight at an event you can give yourself the best view in the campground. This tiny little camper was mounted on a scissor lift! That first step on the way to the Porta Potty is a doozy! [via Adafruit]

[Žiga] was nice enough to demonstrate this smart-watch hack by displaying our name and logo (we love pandering!). It features the MSP-WDS430 which is a surprisingly stylish offering from Texas Instruments. In addition to analog clock hands it has an OLED display driven by the MSP430 inside.

Here’s a quick PIC-based metal detector which [Nicholas] built.

And finally, [Chet] saw the oil tank level sensor we featured this week. He built a nearly identical system earlier this year. The oil level sensor works in conjunction with the custom thermostat he built around an Android tablet.

$50 Backyard Rollercoaster

backyard rollercoaster

This is great. What happens when you bet a group of friends they can’t build a roller coaster in their backyard for under $50? They build one.

They built it almost entirely out of old forklift pallets, some wood from Home Depot, assorted nails and screws, some caster wheels and a folding seat from an old arena. It was built in just over 9 hours by three people. Once assembled they tested it with a 15lb cinder block — safety first right? The cinder block survived the ride, and by that logic, a 160lb+ person should be fine as well!

Well… they were right! To finish it up and get into the holiday spirit they also decked it out in Christmas lights and let the neighborhood kids use it all night. The total came to $49.27 from Home Depot for the wood and wheels.

Stick around after the break to see a .GIF of it in action!

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OpenMV: The Camera For Your Next Project


Last month we saw [Ibrahim] tackle the lack of cheap, high speed, high resolution serial cameras with full force. He designed a serial camera based on the STM32F4 microcontroller that’s the perfect solution to anyone wanting to add visual processing or machine vision to a project. It’s cheap, too: instead of the $100 or so you’d spend on a high-end serial camera, [Ibrahim]‘s version only has about $15 in parts.

Now he’s back at it again, with 25 FPS face detection, 30 FPS color detection, a new board with a micro SD socket, and support for USB OTG full speed. [Ibrahim] has been hard at work deep in the bowels of the STM32F4 micro, playing around with the core coupled memory. This allows for some very fast image processing, combined with the micro running at 168 MHz makes for very fast face and color detection.

As for a few benchmarks for this camera, the maximum resolution is 1280×1024, and at 88×72 resolution this little board can output at 60 FPS. Of course everything is limited by the speed of the serial connection, but there’s a lot of potential in this small serial camera.

No word on how much this board will cost, but [Ibrahim] may be putting a few boards up on Tindie shortly. Here’s to hoping he’ll send us an email telling us when his store is open.

An Awesome Electric Bike


Converting a motorcycle to electric is always a favorite project of ours, and [Peter]‘s build is up there with the rest of them.

The bike is a 2002 ZX6E he bought from a salvage shop. It had been parted out over the years and for $250 this very light aluminum frame made the for the perfect electric conversion frame. After learning MIG welding from his brother, [Peter] cut up a few plates and built a motor mount for his new 4.2 kW power plant.

The controller is a 300 amp IGBT he found on eBay, with an extraordinarily sturdy looking circuit built into an ammo box. The motor from the bike was replaced with 16 60Ah LiFe cells providing 52 volts. [Peter] also built his own battery management system using a Cypress PSoC 3 microcontroller and a beautiful custom PCB.

It’s still a long way from being finished, but already [Peter] has a great looking bike and an awesome weekend project on his hands.

Four Cable Drawing Machine Pulls Our Strings


[David] has created a four cable drawing machine for the Telus Spark Science Centre in Canada. Hackaday has featured [David's] unconventional drawing contraptions before, specifically his center pivot pen plotter. The drawing machine is a new take on a drawbot, and could be considered to be close cousins with [Dan's] SkyCam. The premise is simple: A stepper motor with a reel of string is placed at each corner of a square. The strings for all four motors come together at a center weight. When all four strings are taut, the weight is lifted off the drawing surface. When a bit of slack is added into the strings, gravity pulls the weight down to touch the sand.

It’s at this point that a simple premise becomes a complex implementation. Moving the weight in one direction is a matter of reeling out string on one motor, and reeling in string on the other. But what about the two “un driven” strings? They have to be slack enough to allow movement in the driven direction, but not so slack that the weight can dig in and tumble on the sand, causing a tangle. To handle some of these questions, [David] called on [Kevin] to write some software. [Kevin] created a custom kinematics module for LinuxCNC to control the drawing machine. The drawing machine runs on Gerber Code, similar to a CNC. Simply feed the machine Cartesian coordinates, and [Kevin's] module converts to steps.

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