Don’t let the friendly smile on this RC cart fool you, it will take your strawberries away — though that’s kinda the point. It’s an RC car that [transistor-man] and a few friends modified for carrying freshly picked strawberries at strawberry fields so that you don’t have to.
They started with an older Traxxas Emaxx, a 4-wheel drive RC monster truck. The team also bought a suitable sized water cooler at a local hardware store. A quick load test showed that 5lbs collapsed the springs and shock absorbers, causing the chassis to sink close to the ground. The team had two options: switching to stronger springs or locking out the springs altogether. They decided to replace one set of shocks with metal plates effectively locking them. After that it was time for some CAD work, followed by the use of a water jet to cut some aluminum plate. They soon had a mounting plate for the water cooler to sit in. This mounting plate was attached to 4 posts which originally held the vehicle’s Lexan body. A bungee cord wrapped around the cooler and posts on the mounting plate holds the cooler in place.
Some initial testing showed that the vehicle moved too fast even in low gear and tended to tip over, as you can see in the first video below. Some practice helped but a 3:1 reduction planetary gearbox brought the vehicle down to walking speed, making a big difference. A trip was arranged to go to local strawberry picking field at Red Fire Farms, but not without some excitement first. At 1AM the UNIK 320A High Voltage Speed controller emitted some magic smoke. A quick check with a thermal-camera found the culprit, one of the MOSFETs had failed, and after swapping it with one that was close enough they were back in business.
As you can see in the second video below, testing in the strawberry field went very well, though it wasn’t without some tipping. Kids also found it a fun diversion from picking strawberries, alternating between mock fright and delight.
We’ve covered many thermoelectric beverage coolers in the past, but none come close to the insane power of the AbsolutZero. [Ilan Moyer] set out to design a beverage cooler that chills a drink from room temperature to 5 degrees Celsius as quickly as possible, and it looks like he succeeded. The AbsolutZero consumes around 2.5kW of power and runs 8 water-cooled thermoelectric modules to quickly chill a drink.
[Ilan] put his machinist skills to work and fabricated many custom parts for this build. He machined water blocks for each thermoelectric cooler out of solid copper which draw heat away from each thermoelectric cooler. He also fabricated his own bus bars to handle the 200A+ of current the system draws. To transfer heat from the beverage to the thermoelectric modules, he turned and milled a heat spreader that perfectly fits a can of any beverage.
[Ilan]’s design uses a closed-loop water cooling system and 4 radiators to dissipate all of the heat the system produces, which is quite a lot: thermoelectric modules are typically only 10-15% efficient. The whole design is buttoned up in a custom polycarbonate enclosure with a carrying handle so you can conveniently lug the massive setup wherever quickly chilled beverages are needed. Be sure to check out [Ilan]’s build photos to see his excellent machining work.
If you are looking for a way to spice up your summertime parties, try following [Pastryboy’s] lead. After letting the idea rattle around in his head for a few years, he finally built himself the cooler he always dreamed of.
[Pastryboy] was originally inspired by a YouTube video he found a few years ago. He took the basic concept and rolled with it. He started out with a mini fridge he found for $10. He removed the compressor and other plumbing bits. He also removed all of the internal shelving. Any leftover holes were patched up with silicone. Now when the fridge is laid on its back, it’s essentially the same as an ordinary cooler.
Next [Pastryboy] purchased two 6.5″ Boss speakers and an inexpensive head unit. He drilled a few pilot holes in the side of the refrigerator and then used a jigsaw to cut the holes to the proper sizes. Once the speakers were mounted in place, he needed to find a way to waterproof the inside. This was accomplished by using some small plastic bowls. The edges of the bowls were attached to the cooler wall using silicone.
[Pastryboy] was able to run most of the cabling through the inside of the cooler’s walls. The system is powered by a 12V lead acid battery. He chose a specific model of battery that can be stored in any orientation and that can handle being knocked around a little bit.
Next he added a couple of handles to the sides to make it easier to transport. A small bit of ski rope was attached to the inside of the lid, preventing the lid from flopping completely open. [Pastryboy] also added a drain to the bottom to make it easier for one person to empty the cooler. The final touch was to pretty it up a bit. He sanded down the entire thing and gave it several coats of red paint. The end result looks very slick.
When you go to the beach or on a camping trip this summer, notice how you pack your cooler. Your beverages already come in a box, yet you remove them and put them in a larger, insulated box. [Jason] thought it would be a great idea to just add insulation to a case of soda (or other beverages, we assume) and ended up making a custom soda cooler.
The fabrication of this cooler is actually pretty simple. A layer of flexible foam is sandwiched between two layers of waterproof vinyl with spray glue. After tracing out a pattern, [Jason] then cut this fabric into panels and glued them together into a soda box-sized cooler. Simple, elegant, and something even hackers that didn’t take home ec can put together in a few hours.
As an aside, we at Hackaday seem to forget the ‘softer’ builds of fabric, foam, and paper far too often. That doesn’t mean we eschew these projects; I have a barely post-war Singer 15 sewing machine right above my workbench. Send us a tip if you have one of these soft hacks. We’d love to see it.
The image on the left shows the first iteration of the system which pumped cool water from a large jug through a loop of plastic tubing which he wears around his neck. To refine the design he build the version on the right. As a reservoir he grabbed a water-proof ID container meant to keep your valuables dry in the pool or ocean. Inside there’s a pump which he runs off of a 5V battery supply. It circulates water through the neck strap which is a piece of plastic tubing.
This will work for a time, but as the cold water picks up your body’s heat the effect will be lost. We think he needs to add a Peltier cooler to the reservoir in the next iteration. It might help to refine the loop to increase its ability to transfer heat where it touches your skin.
There’s demo of the most recent version embedded after the break.
Members of theTransistor, a Provo, Utah based Hackerspace, are showing off their entry in the Red Bull Creation contest. This is an all-in-one energy drink delivery system. It can take a warm can of Red Bull from a reserve rack and turn it into a chilled cup of goodness in no time. And it (kind of) cleans up after itself too!
The process starts when a can is opened by lancing it through the side walls. At the upper right corner of the rig you can see the apparatus that is responsible for this beverage extraction technique. The drink drains from the newly created openings into a funnel below. It then enters a heat exchanger the team built by surrounding an aluminum pipe with several copper pipes. The copper has ice water circulating through them from the orange bucket that serves as the reservoir. By the time the drink gets to the cup on the bottom left it is ready to drink. The empty can is crush, falling into a bin and making space for the next in the 16-can backup supply.
It’s not a proper humidor in the technical sense (there isn’t any specific way to moderate the humidity) but [Dzzie] came up with a couple of ways to keep his cigars cool in the summer heat.
Both versions use a Coleman electric cooler as the enclosure. This hardware uses a Peltier device to keep it cool inside. The first attempt at use a thermostat with this worked by adding an external relay to switch mains power. A thermostat dial hangs out inside the cooler to give feedback to the relay board. This worked, but it’s a really roundabout approach since the cooler operates on 12V, and this method uses a mains-to-12V adapter. If [Dzzie] decides to hit the road the relay won’t work when the cooler is powered from a 12V cigarette lighter in the car.
The second rendition fixes that issue. He moved to a 12V relay, and used a car cellphone charger to supply the 5V of regulated power his control circuitry needs to operate.