[Gabe's] been wanting to do some embedded development for years, and his other hobby of playing paintball recently provided him with a test project. He’s been working on a custom driver board for his paintball gun. Don’t be confused by the name, GCode is a mash-up of his name and the fact that he wrote the code for the project. It has nothing to do with the G Code CNC language.
At first this might seem like a trivial hack, but this Viking paintball gun has some serious velocity and throughput so he needs a reliable control that won’t just start shooting randomly. Another thing that [Gabe] took into consideration was monitoring the loading process to make sure the paintball is full seated before firing. All of this is handled by that tiny little Femtoduino board. it interfaces with the guns hardware using the connector board mounted above it.
There are several videos sprinkled throughout the build log. But we found the officially sanctioned 12.5 balls per second mode and the ridiculously fast auto-fire clips the most interesting. It should come in handy when on the run from paintball shotgun wielding opponents.
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Check out all the work going on in the cabinet below this typewriter. The hack which automates a mechanical typewriter is for an art installation, but wouldn’t it be fun to build one of these to use as a résumé printer? It really makes us wish we had an old typewriter sitting around.
It would have been much easier to patch into an electric typewriter, but we have seen the string trick used on those as well. In this case a loop of string attaches to the the bar under each key, allowing a pull from below to type the character. An automotive door lock actuator ([Harvey Moon] tells us they’re not solenoids) connects to the other end of the string for every key. But then you’ve got to have a way to drive the actuators and that’s where the protoboard full of forty relays seen to the right comes into play. That image, which was taken from the demo video after the break, shows the board being testing. We’d guess more wires are added later to multiplex the array as we can’t figure out how the Arduino manages to drive all forty of them as shown. One thing we are sure about, the completed project looks and sounds amazing!
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[Dino's] hack this week seeks to create sunglasses that dim based on the intensity of ambient light. The thought is that this should give you the best light level even with changing brightness like when the sun goes behind a cloud or walking from inside to outside. He started with a pair of 3D shutter glasses. These have lenses that are each a liquid crystal pane. The glasses monitor an IR signal coming from a 3D TV, then alternately black out the lenses so that each eye is seeing a different frame of video to create the stereoscopic effect. In the video after the break he tears down the hardware and builds it back up with his own ambient light sensor circuit.
It only takes 6V to immediately darken one of the LCD panes. The interesting thing is that it takes a few seconds for them to become clear again. It turns out you need to bleed off the voltage in the pane using a resistor in order to have a fast response in both directions. Above you can see the light dependent resistor in the bridge of the frame that is used to trigger the panes. [Dino] shows at the end of his video that they work. But the main protective feature of sunglasses is that they filter out UV rays and he’s not sure if these have any ability to do that or not.
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[Herpity] was getting tired of his cat manipulating him into turning on a lamp above her bed every time she wanted a nap. She likes the warmth put off by the light bulb but he knew he could do better than that so he built a bed which includes an automatic heat lamp. To help introduce her to the new enclosure he set it on the chair where she normally naps.
The bed has two parts, the lower chamber acts as the sleeping area. There is a false bottom underneath the blanket which acts a platform for the weight sensors which detect when the cat is ready for a nap. A PIC microcontroller monitors two sensors and switches on mains voltage to a heat lamp once the pre-calibrated weight threshold has been reached. The upper part of the enclosure holds all of the electronic components and makes room for the recessed light housing. [Herpity] included an exhaust fan for the upper chamber but it turns out a grating is all he needs to keep the temperature at an acceptable level.
When [Antoine] and his family leave home for a few days, they usually have to find a neighbor who is willing to care for their cats while they are away. Instead of bothering the people who live next door, he decided it would be best to build an automatic cat feeder (Translation) instead.
[Antoine] originally tried building an auger to distribute the food, but it didn’t work as well as he had hoped. He opted to build a dispenser out of wood instead, driving the feeding wheel with an old microwave platter motor. The motor did not have enough torque to do the job, so he dismantled an old laminator, which had a more suitable motor inside.
He built a large hopper (Translation) out of wood and left over acrylic sheeting, which stores the cat food and houses all of the electronics used in the feeder. He controls the amount of food and feeding intervals using a pair of buttons and a small LCD display, all of which are controlled by an Arduino Nano.
While [Antoine] has not yet shared the source code that drives the feeder, he does have a demo video which you can watch below.
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If you have livestock or outdoor pets you know how important it is to keep them watered, but also know that sometimes you are not around when the trough runs dry. [Buddy] solves this inconvenience with a trip to the hardware store and some creativity.
The automatic water filler is made from some PVC pipe, brass fittings, a faucet supply and a toilet float valve. The PVC is arranged into a hook shape, a fitting is put on one end for a standard garden hose. On the other end a bit of adapting is needed to convert the PVC into a faucet supply, where the toilet valve is hooked up. Now whenever your thirsty beasts get the water too low, the float lowers and tops off the watering hole with fresh H20. That sure beats running out there every day to make sure, especially with summer just around the bend.
There’s nothing quite like [Elliot]‘s cherubic sense of wonder and maniacal laughter after he tests his fully automatic AA battery-launching air gun. That fires 600 rounds a minute. At 200 feet per second.
We need to take a minute and say [Elliot]‘s gun is stupidly unsafe. He used PVC pipe to hold air pressure, so that may… explode one of these days. Also, the AA batteries coming out of the end of the barrel have the same kinetic energy as a .22 rifle bullet.
The mechanics of the gun is a simple blow forward bolt. When he pulls the trigger, the bolt – and battery – are forced forward due to air pressure. After the bolt has cleared a plug, air is allowed to flow through the bolt pushing the battery along with it. Once the pressure in the barrel is back down to normal, a spring forces the bolt back into place and the 23 round magazine loads another battery. Simple, really. [Elliot] posted some pics of his gun on the spudfiles.com forum.
The gun is accurate to about 100 yards. It’s a very impressive piece of engineering for a bit of PVC pipe, but we don’t feel the need to copy this one. Check out the videos after the break to see this thing in action.
Continue reading “DO NOT build a fully automatic battery-launching air gun”