Power Supplies And Transformers; A Learning Experience

October 27, 2010 by Mike Szczys 38 Comments

[Ladyada] is working on a tutorial series covering power supplies. If you’ve ever built an electronic project you’ve used some type of power supply but we think that most people have no idea how you get from mains power to the DC voltages that most small projects use. So if you want to learn, get started with the first installment which covers AC/DC converters based on a transformer like the one seen above.

These transformers are inside the heavy and hot wall-wart plugs that come with many electronics. We used one along with a breadboard power supply when building the pumpkin LED matrix. They use a pair of coils to step down the voltage to a much smaller level. From there it’s a matter of rectifying the AC into DC power, which she talks about in an easy to follow discussion.

We understand this type of converter quite well but we’re a bit foggy on switch-mode AC/DC converters that don’t use a transformer. They’re much better because you don’t have to build a regulator into the target project like you do with wall-warts. Can’t wait until she gets to that part of the series!

Bench Supply With Current Limiting

October 8, 2010 by Mike Szczys 14 Comments

This is a bench power supply with adjustable voltage and current limiting. [Sylvain’s] creation can regulate 0-25 volts while sourcing 0-5 amps. Current limiting is a nice feature as it will allow you to test your prototypes to ensure the power regulator you choose will not be over or underpowered.

This supply is really a two-in-one. The case has two separate circuits so that you can have different power rails going at the same time. There is a microcontroller involved, but the ATmega32 doesn’t do anything more than measure the voltage and amperage and drive the graphic LCD screen. Two potentiometers are responsible for setting the voltage and limiting the current.

[Thanks Sargonout]

Replacement Refrigerator Controller

December 26, 2009 by Mike Szczys 17 Comments

[Michael] got his hands on a refrigerator that he intended to store beer in but found that it ran constantly. Instead of buying a new thermostat he and his friend [Doug] set out to build an Arduino-based controller for the fridge.

The finished project will switch 240v so they’ve used a transformer to power the logic circuitry and a solid state relay to handle the load switching, with a Dallas 1820 for temperature data. Because the Arduino offers more capabilities than the average thermostat hack they also decided to tap into its potential by adding an Ethernet shield. We see the Arduino as a prototyping device and so do these folks. Once the bugs in their first PCB prototype are worked out the circuit will use the ATmega328 and do away with the Arduino.

[via @littlebirdceo]

Ionocraft Aka Lifters

December 8, 2009 by Mike Szczys 40 Comments

It’s hard to believe that in five years we haven’t covered lifters before. This realization was sparked when [Tyler] tipped us off about a lifter project demonstrated at the Kansas City hackerspace called CCCKC.

Lifters, the casual name for ionocraft, fly without combustion or moving parts. We’re not going to tackle the particulars of what makes flight possible, but high voltage is required to feed the phenomenon that provides the lift. One of the first comments when we asked what to do with old CRT monitors was to use them for lifters. The flyback transformer puts out plenty of voltage if you can tap into it without killing yourself (no, seriously, that’s an issue).

This is the method that the CCCKC folks used. Take a peek at the video after the break. If you’re thirsting for more fun with lifters, stop by the Lifter Project.

Continue reading “Ionocraft Aka Lifters” →

A Bright Way To Cycle

October 4, 2009 by Jake W 19 Comments

[youtube=http://www.youtube.com/watch?v=FQrNmnU8kJk]

Want to be visible when cycling at night? [Neon Dean] came up with this possible solution, which he cruised on at Nuit Blanche. Its a bicycle with neon lights mounted on every surface possible. [Dean], who gave a similar treatment to his car, explained how it worked. All of the tubes take their power from a 12VDC battery he carries in a fanny pack. 12V is a far too low voltage to power the tubes, so a step up transformer is used to bring that number way up. [Dean] also decided to install a neon tube on each wheel. In order to deliver power to them, he mounted a rotor on each wheel, with two conductive tracks running close to the edge of each rotor. Two strips of steel act as brushes (in a manner similar to those on slot cars), and deliver the stepped-up power to the tubes. One creative, but perhaps not so bright, idea is [Dean]’s neon tube helmet.

NeonDeanBrushes12Vfanny transformer copy

Pulse Soldering Iron

October 9, 2007 by Will O'Brien 28 Comments

I’m always interested in new ways to solder. [SPman] sent in this diy pulse soldering iron. It heats up in 5 seconds on demand, then cools in about 15. The writeup is a bit terse (since it’s translated from Russian), but it would definitely be handy for larger wiring jobs. The transformer is hand wound, and an oscillation driver forms a sort of crude frequency modulation to run the MOSFETS that drive the heating elements. I’d keep it away from delicate electronics unless you’re confidant of the temperature stability. It was designed for 220V, so you’d need to modify the transformer a bit to get similar performance on a 110V circuit.