Troubleshooting Household Light Timers

December 13, 2011 by Mike Nathan 13 Comments

timer-repair

When [Todd Harrison’s] Christmas lights stayed on well past the pre-defined shut off time, he knew there was something wrong with the timer. He took the device into his workshop and spent some time diagnosing and repairing the device, a process he recorded for all to see.

After busting the screw-less timer open with a hammer, he inspected the PCB for any apparent signs of damage. After seeing what looked like a damaged transistor, he desoldered it from the board for testing. After the transistor passed his tests with flying colors, [Todd] assumed that the fault had to be in the relay which the transistor was responsible for switching.

Sure enough, the relay had shorted out, and upon cutting it open he found that the contact points were fused together. He separated and sanded the contacts down, enabling him to get the timer working – at least for the time being.

Part of [Todd’s] goal with this video was to show off different methods of desoldering, including a manual solder sucker (my favorite), desoldering braid, and a purpose built desoldering iron. If you’re in the market for some desoldering tools, but don’t know what to buy, [Todd] is more than happy to offer his advice.

Continue reading to see a video of [Todd’s] troubleshooting process.

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Simple PCB Vise

December 12, 2011 by Mike Szczys 25 Comments

This one almost got relegated to a links post, but [Ken’s] simple PCB vise (PDF) is just so useful we had to give it a standalone feature. It works so well because he made every design feature count.

For instance, the groove the holds the PCB (almost impossible to see here but look at the diagrams in the PDF linked above) is cut with a dovetail bit, rather than just being a square rabbit. The clamping force is provided by that blue rubber band which simply hooks on a metal shelf peg on each side of the clamping plates. Those plates are machined out of polyethylene and slide nicely along the two nylon rods which keep them aligned. There’s really nothing to break or wear out here, except the rubber band with is easily replaceable. The rubber feet keep it from sliding across the bench as you work.

This is great for soldering, and would go right along with those diy smd parts clamps you made. It’s also a great way to hold onto your prototype boards when you’re working out the firmware.

Aluminum Bending Tutorial And A DIY Brake

December 7, 2011 by Brian Benchoff 10 Comments

What makes a project really exceptional? Part of it is a, ‘gee, that’s clever’ angle with a little bit of, ‘that’s actually possible.’ One thing the Hack a Day crew really appreciates is awesome enclosures. Altoids tins will get you far, but to step up to the big leagues you’ve got to bend some aluminum. Luckily, [Rupert] sent in a great tutorial on bending aluminum sheets for enclosures.

To make his press brake, [Rupert] scavenged a few pieces of 38mm bamboo worktop scraps. After assembling a few of these pieces with some hinges, he was ready to bend some aluminum.

One trick [Rupert] picked up is scoring the sheet metal on the inside of a future bend. For [Rupert]’s project, he sent his 3mm aluminum sheet through a table saw set to cut 1mm deep. Of course this should only be done with a blade designed for non-ferrous metals with as many carbide teeth as possible. Judging from [Rupert]’s homebuilt Hi-Fi that used this construction technique, the results are phenomenal.

Two Telescope Improvements

December 6, 2011 by Brian Benchoff 5 Comments

Despite being a college class everyone regarded as an easy ‘A,’ astronomy is very hard work. Not only do many hours go into capturing a single image, the equipment itself must be constantly monitored well into the freezing cold of night. [Jerry] sent in a few neat projects that have made his nights much more comfortable.

First up is a mod for a focus controller. The focus of a telescope changes constantly with temperature, atmospheric conditions, and especially what filter is being used. The stock USB-nSTEP focuser [Jerry] used required hard-to-find unipolar steppers, so he modded his USB-nSTEM to accept bipolars with a Pololu A4988 driver.

Next up is [Jerry]’s very impressive DIY Off-axis guider that he machined himself. An off-axis guider allows an astronomer to guide the ‘scope without having to deal with a dinky, surprisingly flexible guide scope. We’re really impressed with [Jerry]’s machine skills, but that’s what you get when you’ve got an awesome mill like his.

Building A ’60s Guerilla Homebrew Square Wave Generator

December 3, 2011 by Brian Benchoff 10 Comments

What do you do when you’ve got three broken function generators? Build your own, obviously. Since your workshop has already gone through three of these bad boys, you might find yourself repairing your build. Better not use any fancy ICs and go with a transistor only build.

When [Miroslav] sent in his ‘guerilla homebrew’ square wave generator, we were really impressed. With a relatively simple schematic that uses parts that could be salvaged from old radios, this is a real MacGyver build.

The generator is based around a simple astable multivibrator. It doesn’t provide sine waves, but it’s the easiest circuit to get working. The build started off with a quartet of 2N4401 transistors, but according to the datasheet and the venerable Tektronix 502A, these had a very bad rise time compared to 2N3904s.

[Miroslav]’s project generates square waves up to 2.22 MHz and pulses with a variable duty cycle from 1-49% and 51-99%. Output is either 5 Volt TTL levels or an adjustable 0-3.38 level. The generator is exactly what [Miroslav] needed, so that makes it a great tool in our book.

Cheap DIY Laser Scanner Is Quite Impressive

December 1, 2011 by Mike Nathan 28 Comments

With the introduction of the Kinect, obtaining a 3D representation of a room or object became a much easier task than it had been in the past. If you lack the necessary cash for one however, you have to get creative. Both the techniques and technologies behind 3D scanning are somewhat complicated, though certainly still within reach as maker [Shikai Chen] shows us. (Google Translation)

He wanted to create 3D scanned images, but he didn’t have the resources to purchase a Kinect. Instead, he built his own scanner for about 1/6th the cost. Interestingly enough, the scanner resembles what you might imagine a very early Kinect prototype looked like, though it functions just a little bit differently than Microsoft’s creation. The scanner lacks any sort of IR emitter/camera combo, opting to use a laser and a USB VGA camera instead. While scanning, the laser shines across the target surface, and the reflected light is then picked up by the camera.

So how does this $25 DIY laser scanner measure up? Great, to be honest. Check out the video below to see how well his scanner works, and be sure to take a look through his second writeup (Google Translation) as well for more details on the project.

[via Seeedstudio]

[youtube=http://www.youtube.com/watch?v=jLZ-s9KRzG8&feature=player_embedded&w=470]

OpenPnP Working To Create An Affordable And Completely Open Pick And Place Machine

November 30, 2011 by Mike Nathan 21 Comments

open-pick-and-place

If you happen to do a lot of SMD work, a pick and place machine is an incredible time saver. The problem is that most automated pick and place solutions are well outside of the “small outfit” price range, let alone the budget of a hobbyist.

We have seen some great DIY pick and place implementations around here, though most are lacking professional features or the sort of documentation that would make it easy for others to replicate. The OpenPnP project is looking change things, with a completely open source hardware and software solution with a price target of under $1,000.

Things are already well under way, with plenty of details available in the project’s wiki. According to the development page, a prototype should go into construction in the near future, and development of the pick and place’s control software is coming along nicely.

While things are looking great for the OpenPnP project, they can always use some help to keep things moving. Be sure to check out the project page if you are interested in lending a hand.

To see some of the progress being made, stick around to see a short demo video of the control software and camera in action.

[via Make]

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