[Gene Buckle] built himself a nice custom cockpit for playing Flight Simulator, but during use he found that the gimbal he constructed for the pitch and roll controls was nearly unusable. He narrowed the problem down to the potentiometers he used to read the angle of the controls, so he set off to find a suitable and more stable replacement.

He figured that Hall effect sensors would be perfect for the job, so he picked up a pair of Allegro 1302 sensors and began fabricating his new control inputs. He mounted a small section of a pen into a bearing to use as an input shaft, attaching a small neodymium magnet to either side. Since he wanted to use these as a drop-in replacement for the pots, he had to fabricate a set of control arms to fit on the pen segments before installing them into his cockpit.

Once everything was set, he fired up his computer and started the Windows joystick calibration tool. His potentiometer-based controls used to show a constant jitter of +/- 200-400 at center, but now the utility displays a steady “0â€. We consider that a pretty good result!

[Thanks, Keith]

The Massachusetts Institute of Technology just announced the first course offering in their new online classes program. Great news, it’s an analog design course which is right up our alley. The prototype session will be 6.002: Circuits and Electronics.

If you’re a fan of our links posts you may remember hearing about the MITx program a month ago. After seeing the popularity of the Stanford program MIT is throwing their hat into the ring too. So what is this all about? How does it work and what will you learn? There’s bits of information all over the place. We recommend reading the news link at the top of this feature first. Next you should wade through the 6.002x FAQ and if you’re still interested there’s a big maroon enrollment button at the bottom of the course summary page.

Whew, that’s a lot of links. Anyway, expect to spend 10 hours a week on the class; but it’s all free. Future offerings will be free as well, but MIT plans transition to a pay-for-certificate option: “students who complete the mastery requirement on MITx will be able to receive the credential for a modest fee.” If you still haven’t made up your mind take a gander at the promo clip after the jump.

Read the rest of this entry »

[Joe Fernandez] is fairly new to the hardware side of the hobby, but he seems to have easily found his way on this project. He wanted to build his own web-bridge for his Toro lawn sprinkler system. He pulled it off with style and shows off the spoils of his work in the clip after the break.

He started with an Android ADK, crafting some web magic to use a REST interface and JSON packets as a communications scheme. This makes it possible to control the system from anywhere as long as you have an Internet connection. The rest of the hardware evolved as his needs became clear. The first hunk was to add an Ethernet shield so that he didn’t need to have his Android phone connected to the system for it to work. From there he needed to control the solenoid valves on the system and grabbed three relay shields from Seeed Studios for this purpose.

As you can see, all of that hardware has a home on a polyethylene cutting board. The terminal blocks at the bottom keep the connections nice and neat as they interface with the sprinkler system. We were happy to hear that the stock controller still works, this add-on doesn’t permanently alter it in any way. That’s going to be important if he ever wants to sell the home.

Still using a traditional sprinkler instead of an in-ground system? Perhaps this variable range hack is for you.

[Bradley Gawthrop's] biggest gripe about his laser cutter is the lack of Mac support. We don’t think we’d have any gripes if we owned one of these (yeah, that’s a lie…) but we can understand his second biggest issue which is the inability to see the work piece once it’s inside the machine. He figured out a very easy way to light the area as the cutter gets to work.

It occured to him that the optical head is always directly above the part of the work piece he was interested in seeing. He had been using a flashlight to shed some light, but what if he just added lighting to that head? The circuit is certainly nothing hard; some LEDs, resistors and a power source will do the trick. But routing the power is where things get more difficult. You need flexible wiring strung just right so as not to restrict motion on the X/Y axes. Most of his time was spent routing some 14 gauge stranded speaker wire for this task. He added his own 5V DC supply to power the adhesive LED strip which enjoys a resting place on the bottom rail of the head unit. Boom, problem solved.

We’ve featured dozens of digital camera triggers over the years. Very rarely do we come across one as well designed as [Viktor]‘s ‘lil bang sound trigger that snaps a picture whenever a microphone picks up a loud noise.

[Viktor]‘s build is based around a PIC16F microcontroller with an LM386 amp connected to a microphone. On the front of the device, the right knob controls the sensitivity of the microphone and the left knob sets the delay between detection and the trigger.

The ‘lil bang trigger connects to the camera through an opto-isolated 3.5 mm jack that is compatible with all the fancy Canon and Nikon DSLRs. The delay between sound detection can be changed from 0 to 255 ms, allowing for precise control over a high-speed photography rig.

All this work comes after the  light-activated trigger [Viktor] built for taking pictures of lightning. The sound-activated version wouldn’t work for lightning pics, but he thinks it could be useful for collision or explosion photographic studies. Check out the video of [Viktor]‘s ‘lil Bang in action after the break.

Read the rest of this entry »

If you’re forever alone we’d guess you’ve long since stopped crying about it. But if you’re still prone to shed a tear on a dateless Valentine’s day this project’s for you. [Mikeasaurus] spruced up this pillow to play a tune when it senses your lonely soul. It’s got a moisture sensor which triggers an audio greeting card just when your weeping really starts to get soggy.

If you look closely at the top portion of the white fabric in the picture you can see there are rows of stitching. These hold a matrix of conductive wire mesh fabric on the inside of the pillow case. There are two buses made up of alternating rows (think of the tines of two forks pointed together) which make up the probes. When the gap is bridged by moisture a transistor circuit triggers the audio bits from a greeting card to play a song. Check out the demo after the break. We’re not satisfied that [Mikeasaurs'] couldn’t even bring himself to cry real tears for the clip, but maybe years of solder fumes have clogged up those tear ducts.

Read the rest of this entry »

It’s not roses or jewelry, but we hope [Erik]‘s light-up USB heart will be appreciated by his significant other. When the two heart pieces come in contact with each other, each side lights up.

[Erik] started his build by cutting two half-heart shaped pieces out of polycarbonate. After drilling a few holes for LEDs and wires, magnets and reed switches were installed along the ‘broken’ side of the heart. Whenever the hearts come in contact with each other, the magnets trip the reed switches and light up both sides of the heart.

There is USB flash drive embedded in each heart half is loaded with a portable Dropbox. When the USB drive is plugged into a computer, the dropbox steps into action and synchronizes the photo album stored in each heart half. No matter how far apart they are, [Erik] and his SO can share pictures through their glowing LED hearts. Not to come off as a hopeless romantic, but this sounds like something we’d like for Valentine’s day. We’re hoping [Erik]‘s SO thinks that as well.

[Shahriar] is back with a new “The Signal Path†video. It has been a few months but it is okay because his videos are always packed full of good information. Some new equipment has been added to his lab and as an added bonus a quick tour of the equipment is included at the start, which is great if you like drooling over sweet machines.

The real focus of the video is high speed data communications, getting up into the GHz per second range. [Shahriar] covers filtering techniques from simple RC low pass filters to pretty complex microwave filters. Explaining frequency and time domain measurements of a 1.5Gbps signal through a low bandwidth channel. He also shows how equalization can be used to overcome low bandwidth limitations.

It is an hour long video jam packed with information, so you might want to set aside some time and have a pencil on hand before going in. It is well worth it though, so join us after the break.

Read the rest of this entry »