Attiny25 Based Function Generator Causes a Wave

Function generators are a handy bench tool to have around, and while you can usually cobble something together that works, it is much more handy to grab a device when you need it. Thats where this function generator sent to us by [Mohonri]comes in. Based around a ATTiny25 and a rail to rail op amp which is able to replicate frequencies from 1Hz to about 40KHz, in square, triangle, and sinewaves simultaneously.

The function generator also features independent amplitude control on each output. And it’s all on one palm-sized, single-sided PCB. The main part of the code is split into two parts: the main loop gets the inputs and constructs a waveform table in SRAM, and then an ISR reads that table and outputs it to one of the timers, which produces a PWM output, which is low-pass-filtered and then passes through a potentiometer (for amplitude control) and then to an op-amp before landing on a set of terminals.

Though its not 100% perfect, trading speed for a 6 bit resolution, it should be more than enough for most electronic projects. You can pick it up in kit form from the on-line shop, but schematics, software and PCB layouts are also available for download.

Designing a Smarter RF transceiver

Two  months ago we featured a transceiver based on the Microchip MRF49XA, and a lot of feedback was sent to [hpux735] requesting that some brains be added onto the system. [hpux735] decided that if he was going to do it, might as well go the distance and make a make a native USB transceiver.

The prototype model is designed for use with the Atmel AT90USBKey, and uses the LUFA USB framework. The protocol and packet format was revised, and a Hamming Code implementation was built using look-up tables to give error control. Finally once the prototype was ready to go [hpux735] created some awesome little PCB’s that contain the AVR, radio, antenna hookups, and blinky lights (no project is complete without blinky lights) are all ready to go when you are.

This project has come quite a long way, covers 3 blog pages, uses a fair bit of ribbon cable, but you just got to love when a plan comes together.

Hackaday Links: February 8, 2012

Most useless machine

We love ‘em, and we hope you do too. Here’s [Phase2plus'] take on the most useless machine.

Scratching like it’s 1989

[Nick] spent three bucks at the thrift store and ended up buying days worth of fun with this cassette player. He hacked it to scratch like vinyl.

3D printed jawbone

This lady now has her own 3D-printed jawbone. We’re not talking about the Bluetooth headset… it’s an actual bone replacement! And yes, the skeleton for the Terminator was 3D printed… we’re that much closer now. [Thanks Steve]

Hexbug superbowl

Why not let robots decide our sports gambling choices? [Eric] let this slew of HexBugs battle it out as an early indicator for who would win the Super Bowl. Seems he has no shortage of the little toys, all of which received an MSP430 upgrade. The firmware actually implements obstacle avoidance, but he makes a poke at the Chicago Bears who seem to have the same mission.

Foil fix for worn out remotes

[Viktor] found an interesting repair tip. If you’ve got remote controlers whose buttons are not working so well anymore you may be able to fix them with tin foil. He uses a single-hole punch to clip out circles which are attached to the underside of the misbehaving button. Worth a try!

Single hand keyboard for tablets

To us it makes a lot of sense to hold the tablet in one hand and type with the other. That’s exactly how [Adam Kumpf] has implemented this one-handed typing interface which was originally conceived by [Doug Engelbart].

As you can see, there’s a large contextual area for each finger on your right hand. Letters and navigational keystrokes are input through this interface based on single touches, or combinations up to and including all five digits. This offers up 32 possible combinations (including all on and all off) which is enough to cover the modern English alphabet.

[Adam's] demo page works for most tablets so give it a whirl. Yes, it works with iDevices too which is a surprise as we would have thought this was using Flash. If you’re not near a touch-sensitive device you can get the gist of the operation from the demo video embedded after the break.

Now, who’s going to be the first to make this into a replacement keyboard on iOS 5?

[Read more...]

Quadcopter build ready for first flight

[Abhimanyu Kumar] has been hard at work building and posting about his quadcopter. So far he’s published ten installments for this build, letting us relive the adventure vicariously. But it’s number 11 that we’re really excited about as he plans to share the first free-flight footage in that one.

The bug was planted in his brain after hearing that a quadcopter was used to shoot some of the footage in Spiderman 2. He wanted one to call his very own but the cost of a ready-made unit was out of his league. So he decided to build one instead. The first version uses aluminum bracket for the cross making up the motor mounts. He added LEDs to liven things up and even made a demo video of the thing tied to a table (no IMU yet so free flight would be fatal). After this stepping stone he decided to go with a Wii Motion Plus and Wii Nunchuck as the positioning feedback sensors. There is also a body redesign with helps lighten the load.

It’s a fun project, and we can’t wait to see where he goes from here!

Hydroponic strawberries sweeten up winter dolldrums

Add some fruit to your indoor bounty with this hydroponic strawberry farm. [Dino] whipped this up as his 45th hack a week episode (getting pretty close to his year-long goal). He used parts you probably already have sitting around the house somewhere. But even if you bought everything and used it once you still wouldn’t be out much.

A plastic storage container serves as the base. [Dino] also grabbed four identical plastic containers (large yogurt containers would work here) to host the plants. He cut off the bottom half and inserted some netting to keep the plant from falling through. After tracing the size of the container on the enclosure’s lid he cut out holes which will host each plant. This provides a way to dangle the roots into the nutrient solution which is kept oxygen rich with an aquarium pump and two air stones. It certainly deserves a place next to that salad farm you threw together. Don’t miss [Dino's] build video after the break.

[Read more...]

Yet another 3D printer

What would you do if you wanted to demonstrate a linear bearing system? If you’re like [Bart] the obvious solution is building a tiny little 3D printer. [Bart]‘s Quantum ORD Bot is constructed out of a previous project of his, the MakerSlide linear bearing system.

The idea of a printer made out of MakerSlide materials came from [Bart]‘s invitation to ORD Camp. The fact that this build went together in about 5 hours speaks volumes about the simplicity of the MakerSlide system. Right now, the printer is designed for NEMA 14 motors, but for larger builds there’s plenty of room for the larger NEMA 17 stepper motors. [Bart] put up a build log for his printer up on the buildlog.net forums.

The MakerSlide system has already been used in an open source laser cutter project, but [Bart] really just wanted something to demonstrate his linear bearing system. We like the bot anyway; not enough stuff is made out of aluminum extrusion these days.

[Bart] is going to be showing off his bot at the Chicago hackerspace Pumping Station: One tonight, February 8th. Stop by and check it out. Snap a few pictures for us and we’ll put them up.

EDIT: [gigawatts121] was kind enough to send in a picture of the printer at Pumping Station: One. There’s also a video of a calibration cube being printed courtesy of [David] in the comments. Check that out after the break.

[Read more...]

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