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Sure, [Hunter Scott's] Breathalyzer can only differentiate between hammer and sober, but look how nice it came out. He’s using an MQ-3 alcohol sensor which, from previous projects, we know is very difficult to accurately calibrate. But if you want to monkey around with embedded systems you’ve got to have a goal. [Hunter] chose a gorgeous aluminum project enclosure, adding a big LCD display to the to the lit. The switch on the bottom selects between on, off, and charging modes. He’s using a USB charger from Adafruit to top off the lithium battery inside. Everything runs on 3.3V with the exception of the sensor which gets its 5V supply from a boost converter. An Arduino is the brains that pulls everything together.
See [Hunter's] video description of the project embedded after the break.
After [Luke] built a suitcase mini-ITX rig for LAN parties he was left with one problem: he didn’t have any speakers and he didn’t want to use headphones. Not wanting to do something boring like a USB-powered speaker setup, he built a PVC Boombox.
Built around 3 inch PVC pipe, the boombox houses an off the shelf 15 W amplifier, bluetooth receiver, and charge controller. [Luke] found a deal on a dozen 1400mAh lithium ion batteries and despite the standard, “if you don’t know what you’re doing, don’t use lithium” trope commonly given as advice, he forged ahead anyway. [Luke] picked up a power converter that charges the batteries and provides some protection. The batteries are charged though wall power with a transformer and a huge cap scrounged from an ATX power supply.
[Luke] is pretty pleased with his boombox. Not only does it put out some decent quality sound, the battery life should be tremendous. It’s not a ground-up build, but we think it’s a pretty nice project. [Luke] will be taking the ‘boomtube’ to the Detroit Maker Faire next month, so if you see him make sure to say hi.
I knew this was coming out, but [mike] was kind enough to remind me. [Ben Heckendorn]‘s latest How-To is up on engadget. He provides a method of building your own A/V switch with as many inputs as you want, cheap. Each input uses a $.50 bus switch – literally, you could build one with 20 inputs if you really wanted to. (add some shielding if you do) If you’ve got too many game consoles, this might be your ticket. You can probably use the same trick to build a component video switch if HD’s your thing.
[Dave] Had been working on a cell phone activated remote start for his car for a while when we posted the GSM car starter. While both do carry out the same job, we feel that there is enough good information here to share. He’s gone a pretty simple way, by connecting the vibrator motor leads to a headphone jack. He’s using that signal to then activate the remote start by setting off an extra fob. Though it is amazingly simple, this version does have an advantage. As [Dave] points out, his cell phone has several features which could be utilized to automate some of his car starts. He can set alarms as well as recurring calendar events to get his car started without his interaction. Lets just hope he doesn’t forget and let his car run too long unattended, especially if it is in a garage attached to his house.
[Knife141] lets this monkey push him around all day long. It’s a whimsical touch for his scratch-built electric scooter. He started the build without a set of plans, cutting angle iron and clamping it together until the frame looked about right. Once the welding was done, he began adding all the parts to make it functional. There are front and rear brakes, operated by a lever on the handlebars. The rear wheel has a sprocket bolted to it, along with some spacers to give the chain adequate clearance.
Inside the saddle enclosure you’ll find a set of three lead-acid batteries. These are 12 volt 10 amp models that provide 36 volts of juice to the electric motor. The only thing we know about the electronics is that both the motor and the controller were purchased at a surplus store.
The sock monkey that pushes him around is sort of an afterthought. But since it’s just a couple of wheels with the feet attached, this might make a fun project for the kids to add to a bike.