Auto-Focus assist hack keeps improving

[Adrian Onsen] keeps making improvements on his auto-focus assist hack for DSLR cameras. The module seen above is version 3.0, which makes a few changes to the previous hardware and also presents a much more finished look.

With version 2 [Adrian] was using a defocused laser to illuminate dark subjects so the DSLR auto-focus could be used. It worked, but wasn’t really ideal. This time around he’s swapped out the laser diode for an autofocus assist lamp salvaged from a Canon 550EX he picked up ‘as is’ on eBay. It is mounted on the front of his project enclosure, using two alkaline batteries for power. It sounds like [Adrian] is struggling a bit with his circuit design. He want’s to make it work with either alkaline or rechargeable AA batteries (just two, down the from four AAAs used in version 2) but so far the rechargeable are a no-go. They power the circuit, but must not put out enough light for the sensor to work.

Future plans include getting rid of the external cords by adding a hot shoe connector.

Simple low toner workaround squeezes out a few extra pages when your printer refuses

low-ink-hacking

[Andrew] was getting ready to print out an assignment when his Samsung printer suddenly started blinking a red error light at him. Unable to find any documentation explaining the issue, he called Samsung directly and found that it was indicating the toner cartridge was nearly empty.

He held down the button that prints a test page, which came out just fine despite the printer’s insistence that there was not enough toner left. Annoyed at the fact that he felt Samsung was trying to strong arm him into buying another pricey toner cartridge, he looked for a way around the restriction.

He discovered that his printer’s software allowed him to specify a custom test page document, though it required that the document be in PostScript format. After a few shell commands, he had his document converted and was on to bigger and better things.

While a bit time consuming, his workaround should let him get by on this toner cartridge at least for a little while longer. We imagine that since he’s using Linux, the process could probably be scripted to save time, though we’re not sure if the same can be said for Windows-based PCs.

A doorbell pleasing to both the ears and eyes

campanello-doorbell

When [David] moved into his new house, one of the things he noticed was that his doorbell was pretty lame. Coming from a home equipped with a solenoid and chime bell, his new wireless solid state doorbell sounded terrible to him.

Crummy sound aside, the doorbell hardly ever worked properly, but alas, other projects cropped up and years went by before [David] addressed his doorbell problem. Like many things that take a long time to come to fruition, we think his resonator bell based solution was well worth the wait.

One of his main goals was to make a nice sounding doorbell that also looked great. He mounted a kid’s resonator bell toy on a sheet of wood, creating his own wooden mallets for the job. He initially had a tough time locating actuators for his doorbell, but found a solution in geared pager motors as featured in another xylophone hack on Make. With the hardware taken care of he focused on the electronics, which consist of a pair of Arduino clones – one on the display and one in his basement.

Stick around to see [David’s] Campanello doorbell in action, and be sure to check out his site for more details if this sounds like something you would like to have in your home.

[via Make]

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C bit field structures for microcontroller multitasking

So you’re getting better at programming microcontrollers and now you want to do several things at once? You know better than that, microcontrollers are only capable of processing one thing at a time. But if you’re clever with your coding you can achieve something that behaves as if several things are going on at once. The most common way to do this is to set a flag using an interrupt, then use the main loop to check for that flag. [S1axter] posted a tutorial on this topic where he uses bit field structures to help simplify time sensitive events.

We think [S1axter] did a fantastic job of explaining this moderately difficult topic clearly and quickly. In the video after the break he begins by explaining what a bit field is and how it is defined. Basically you’re using a C structure to track a flag using just one bit of storage. This way the flag is either set or not. We suggest you pay careful attention to how he declares the structures as volatile, so you don’t have unexpected behavior when you try it yourself.

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Kitchen Hacks: Sous Vide builds don’t need to cost an arm and a leg

It’s not that we haven’t seen inexpensive Sous Vide builds. It’s just that we enjoy the fact that [Kelvin's] Sous Vide machine gives new life to unused things. The cooking vessel is a crock pot which he acquired for just $3. He housed it in a large Styrofoam box which he got for free through his local freecycle program. The circulation pump is a $0.99 fish tank part that pushes about ten gallons per hour.

He even hunted around to find the best prices on the control circuitry. The PID controller is obviously the most important part, as it will regulate the cooking temperature. He found a greatly discounted module that set him back just over $30. It even has a self-learning feature that sounds like it’s handy (not sure if all of these have that though).

Check out the video after the break. We like the use of his old RAM heat sinks to help dissipate heat from the solid state relay that drives the heating element. Since that SSR is inside of the foam box we could see heat becoming an issue. This way it’s dissipated, but not wasted.

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The Picture Post – Observe Your World in Extreme Slow Motion

The “Picture Post”, a tool for a program going on through the University of New Hampshire, is a method of taking what amounts to extreme time-lapse photography. The purpose of this project is to observe the world around you with a 360 degree view taken at a regular interval.

The setup is quite simple consisting of a 9 inch diameter post, and an octagon to set your camera against.  Just place your camera one edge, take the picture and repeat around the octagon until done. You can register on their site to make your post official and contribute to society’s general knowledge about the environment and seasonal changes.

Although interesting in itself, this concept could be applied to many situations that one would want to record in this manner.  For instance, a “hacker post” could be set up in a hackerspace for members to record their projects on or even the progress of the building itself.  For another much less developed way to take photos, check out this trigger device using air freshener parts!

via [Make Magazine]

Musical greeting card with minimal parts

We’re all familiar with those musical greeting cards. Give the Hallmark store $10, and you have a card with a microcontroller inside that plays one of several songs available. [Jarv] was playing around with translating MIDI tracks to square wave songs with an Arduino earlier, so he decided to see how cheaply he could reproduce these musical cards. The resulting build allows him to put any song he wants in his card and costs less than the Hallmark offering.

The circuit is extremely minimal – just an ATtiny 85, a battery holder, and two piezo speakers for two-voice harmony. After soldering up the battery and speakers, [Jarv] needed a way to get music on his chip. For this, he used MuseScore, a music notation program that allows [Jarv] to merge multiple voices together.

Once the sheet music was cleaned up, [Jarv] used his XML2H Python script that takes MIDI data and spits out frequencies and delays. In the end, [Jarv] spent less than $5 on his greeting card – almost cheap enough to start thinking about musical throwies to complement the batteries, LEDs and magnets on our window flashing.

Check out the video after the break to hear [Jarv]‘s circuit play the theme from Toy Story.

[Read more...]

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