Make Presents: The Multimeter

January 26, 2011 by Caleb Kraft 17 Comments

This video falls under the category of things we want to send people when they ask “how do I get started with electronics”, and we get asked that a lot. For those of you who have been working with electronics ~~for years~~ at all, you can skip this entire video. That is, unless you really want to watch an instructional video on multimeters. In the video, which we’ve included after the break, they talk about the differences between different meters, the common uses and how to actually use the meter to get the results you need. Stuffed full of useful information, this video will get those of you who are still reading up to snuff pretty quickly. Now go use your multimeter to do some hacking!

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Magnetic Digital Scale

January 21, 2011 by Mike Szczys 20 Comments

Above you see a solenoid being used as a digital scale. The magnetic field from the coil in the base levitates the platform above, where a load to be measured is place. This floating platform has a permanent magnet in it, hovering above a hall effect sensor in the base. As the distance between that magnet and the sensor changes, the measurable magnetic field changes as well. The hall effect sensor is linear so the measured value can easily be correlated with a weight. In the video after the break [Vsergeev] demonstrates the device using test weights to show off its 0.5 gram resolution. He thinks that with a few hardware improvements he could easily achieve 0.1g accuracy.

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Make Your Own Odometer From Scraps

January 19, 2011 by Greg R. Jacobs 11 Comments

For those out there who would enjoy a quick and interesting weekend project, this odometer made by [PeckLauros] is for you. Featured on Instructables it is made from the simplest of materials including some cardboard, a calculator, wires, glue, hot glue, magnetic drive key, an old CD and a reader, and a rubber band. The magnets, when attached to the CD work in a calculation to add 0.11m to the calculator when a magnet closes the circuit. [PeckLauros] points out that since it is a homebrewed device, it does have flaws such as adding 0.11m twice when the CD is rotated too slowly. It is easily fixed by simply running faster. The video is below the break.

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$20 Fuel Injector Tester

January 16, 2011 by Mike Szczys 39 Comments

[Dino] is an auto mechanic and needed a way to test out fuel injectors. Commercially available tools start well over $100 and go up from there, but he built his own for about $20.

The injectors have a coil in them that needs to be tested. His design calls for a series of 0.008 millisecond pulses to test the coil. He started by setting up a 555 timer to output a one second pulse. This signal is fed into a second 555 chip that outputs the 0.008 pulses and in turn actuates a MOSFET to switch the coil on and off. To use it [Dino] connects to a 12V bench supply and to the injector, using a single button to start the test. See him explain the setup in the video after the break.

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Pin Header Sizing Machine

January 13, 2011 by Mike Szczys 41 Comments

[Ammon Allgaier] built a tool that can break apart pin headers with a high level of precision. In the video after the break he demonstrates the built-in features. They include an adjustable stop to select the number of pins you’d like in each chopped segment. There’s also a small groove in the input side which the plastic frame of the header rides in. Just insert until it is touching the stop, and push down to break the header at the correct location. A couple of springs return the cutting tooth to its resting position, allowing you to make quick work of chipping up a 40-pin blank. This machine will become a nice companion for that automatic wire cutter.

This is great for single headers but we’ve long been on the lookout for a reliable way to snap off double pin headers. Far too often we make mistakes when trying to use two pair of pliers. If you know of a better way, please share your method in the comments.

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Hold, Fast, And Max Features On A Digital Caliper

January 12, 2011 by Mike Szczys 67 Comments

While adding an RJ-11 connector to his digital calipers [BadWolf] slipped, shorting out a pin and accidentally discovered new features. He intended to add a port for reading measurement data electronically, but after the slip-up an ‘H’ appeared on the LCD screen and the measurement was frozen at the same number. At first it seemed like he may have killed the device, but this is actually a hold function. A little bit more playing around and he discovered that a combination of button presses can also enable a fast function which speeds up the rate at which the display changes its reading. There is even a max function that only updates the display if the reading is higher than any previously displayed measurement. These are nice features which he uses by connecting a momentary push switch between two of the output pins, details we gleaned from the annotated video after the break. He doesn’t say which pins work for him, but we’d bet one of them is the ground pin on the port, and the other is one of the two data pins. Do some investigating with your own calipers and let us know what you find in the comments.

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Button Cell Connectors For Breadboarding

January 11, 2011 by Mike Szczys 34 Comments

We’re working on a project that has a battery backup, but we don’t have any more coin cell holders on hand. No problem, we remember seeing a double pin header used for this. But when we tried to shove the CR2032 battery in between the pins it was a no-go. We could swear we’d featured a project that does this but couldn’t find it here at Hackaday. After much searching we came up with the Guerrilla battery holder which is seen on the left. No wonder it wasn’t working, the CR1212 in that picture is a much smaller package. So we figured we’d have to come up with something else, until inspiration struck.

There must be some other way to configure the pin header to work with a fatter cell body. On the right you can see that a diagonal orientation works like a charm. Join us after the break for a couple of close-ups of that connector and our thoughts on using this with a variety of different cells.

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