66% or better

Beach stereo

[Adam] wanted a stereo that could stand up to rain and keep sand out. He ended up building this beach stereo out of a cooler. The cooler’s already made to be water tight. He cut holes in the front and back for marine speakers and added a water-tight bezel and cover for the controls on the deck. Inside you’ll find a marine battery to power the unit. Now he and his friends can rock-out even in poor weather thanks to this portable and rugged unit.

Hack together a Coffee Roaster

For most people, making coffee entails taking a couple scoops out of a can of pre-ground coffee, adding water, and pressing “Go” on the drip machine. To others coffee brewing is an artform, and want as much control over the process as possible. For those without an overflowing bank account for a home roasting machine, Evil Mad Scientist Labs have put together a general guide for throwing together a Coffee Bean Roaster and cooler (which is apparently just as important as roasting) from a low cost hot air popcorn popper. The home roasting scene is even big enough to warrant its own Wikipedia page, which also mentions using a popcorn popper as a bean roaster.

The guide includes some great simple circuit diagrams to keep in mind when hacking your own, as well as a good explanation why you shouldn’t just clip out the heating coil for cooling mode.

Peltier-based cooling/heating backpack

[Max Weisel] recently created a Peltier-based cooling/heating system that fits into a backpack. The system uses two Peltier units, each running at 91.2 watts, with computer heat sinks mounted on one side of the unit to dissipate the excessive amounts of heat generated. While he was originally trying to build a cooling backpack, the use of the Peltier units meant that the cool side would become warm when the direction of current was switched, meaning that the backpack could become a heating backpack with the flip of a switch. In order to power the two Peltier units, he uses two 12v motorcycle batteries, weighing in at around 5 pounds each. While this backpack might be a little heavy for your back, it looks promising for anyone who needs to keep things cool (or warm) on the go.

Solder paste fridge


MightyOhm’s laboratories have recently decided to start tackling more surface mount work. As part of this upgrade to SMD hot air reflow stations, they’re handling a lot of solder paste. Solder paste is happy at less than 50degF and above freezing, and [Jeff] didn’t want to chance that lead infiltrating his Manwich, so he built this solder paste fridge. The main unit is a standard 12V peltier based travel cooler. He attached a surplus PID controller with a K-type thermocouple to maintain the temperature while preventing the cooler from being always on. The only adjustment he really had to make was adding a bleed resistor to force the MOSFET to turn off. You can find more pictures of his project on Flickr.

Portable air conditioner


The dog days of Summer are looming just over the horizon like a hot sticky wave of impending doom, but you don’t have to take it lying down. Building a portable air conditioner is cheap easy, and we daresay refreshing.

You’ll need the following materials: a condenser, heater core, or radiator, a styrofoam cooler, a submersible water pump, a few case fans, some adapters to power the works, and a few other materials. The pump circulates cold water through the condenser as the fan pushes air through it and the rest of the box.

We’ve never been huge fans of swamp coolers like this one since they offer no true refrigeration cycle. What’s more, they pump a good deal of humidity into the air, which makes the heat worse in the long run, or creates a vicious cycle of cooling and humidifying. Still, when the heat is scrambling our brains, it’s hard to say no to any relief, however ephemeral.