While hobby brush motors are pretty cheap now adays, there’s always that feeling of why replace when you can rebuild and reuse. As such [John Carr] presents how to change the brush position in motors to revive a dead motor. So long as the motor dies from natural causes commutator wear, the idea is the brushes can be moved along the axes and fixed to a new portion of commutator that’s not worn at all. [John] also goes through the details of some tricky reassembly, but we think to make this complete a guide on brush replacement and commutator replacement might be in order hint hint.
adafruit industries’ latest product is an adjustable breadboard power supply kit. We’ve seen breadboard supplies before, but like most of adafruit’s kits, this is the best design you’re going to encounter. It uses an MIC2941 voltage regulator instead of the more commonplace LM317. It has a very low dropout which means your output voltage can be much closer to the input voltage. Their example is using 3AAA or a Li-Ion battery for an output of 3.3V. Input can be through a barrel jack or terminal blocks. There is a selection switch for 3.3, 5, and adjustable voltage. Using the adjustment pot you can select an output voltage anywhere from 1.3V to within .5V of the 20V maximum input. The adjusted output voltage will remain the same even if you increase the input voltage. Like all of their kits, you can find schematics, assembly and usage instructions, on their project site.
[Chris Paget] is going to be presenting at ShmooCon 2009 in Washington D.C. this week. He gave a preview of his RFID talk to The Register. The video above demos reading and logging unique IDs of random tags and Passport Cards while cruising around San Francisco. He’s using a Symbol XR400 RFID reader and a Motorola AN400 patch antenna mounted inside of his car. This is industrial gear usually used to track the movement of packages or livestock. It’s a generation newer than what Flexilis used to set their distance reading records in 2005.
The unique ID number on Passport Cards doesn’t divulge the owners private details, but it’s still unique to them. It can be used to track the owner and when combined with other details, like their RFID credit card, a profile of that person can be built. This is why the ACLU opposes Passport Cards in their current form. The US does provide a shielding sleeve for the card… of course it’s mailed to you with the card placed outside of the sleeve.
Technology exists to generate a random ID every time an RFID card is being read. The RFIDIOt tools were recently updated for RANDOM_UID support.
What you see above is the culmination of [Zach Smith]’s work building a pinch wheel style extruder for the RepRap. The current RepRap 3D printer uses a screw mechanism to push 3mm polymer filament into a heating barrel where it is melted and then extruded through a fine nozzle. [Zach]’s new version uses a drive gear from SDP/SI mounted directly to the DC motor we saw him teardown earlier. He’s redesigned the carrier for the extruder as well. It’s now much lighter and has provisions for mounting current and future controller electronics along with a magnetic rotary encoder. In the last two days, he’s been doing real world testing. It’s been doing well, but he’s learning to do things like always using a full spool and not trying to run short lengths back to back.
[glacialwanderer], who you may remember from his CNC machine build, recently completed an electric spinning wheel. Spinning wheels are used by knitters to turn raw sheep’s wool into yarn. He went through several iterations before arriving at a good design. Besides the motor, there are two major components to the spinning wheel: the flyer and the bobbin. A Scotch tension brake is used to slow the rotation of the bobbin in relation to the flyer. This causes the wool to twist as it’s pulled on.
He initially tried to just use a dimmer switch with an AC motor. That quickly burnt up. The next version used a sewing machine motor since they’re designed with a variable speed control. Unfortunately, it didn’t have enough torque at low speeds. The final design used a DC motor with a SyRen motor controller. It offered plenty of power and at ~$150 it’s still less than the cheapest commercial models on eBay. You can see a video of it and the spinning process embedded below.
Continue reading “Electric spinning wheel”