Squeezing The Juice Out Of Some AA Batteries

[Ray’s] breadboard power supply lets you drain the last traces of power from ‘dead’ AA batteries. Electronics that are powered off of disposable alkaline batteries have a cutoff voltage that usually leaves a fair amount of potential within. Since many municipal recycling programs don’t take the disposables (you’re just supposed to throw them in the trash!) we love the idea of squeezing them for prototyping use.

His design uses just one IC, the MCP1640, along with a handful of passive components. The chip is a boost converter with a startup voltage of just 0.65V, which means the batteries themselves – normally starting life above 1.5V – can be used until they drop to about 0.3V each.

Above you can see the kit he is selling. But it’s an open source project and the circuit is so simple we’re sure you can build your own. Add that boost converter chip to your next parts order for around $0.40.

[Ray] made a nice demo video for the device which you can see embedded after the break.

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Cockroft-Walton Multiplier Can Output Positive Or Negative Voltage

If you’ve already dipped your toes into high-voltage power supply pool you may be thirsty for a bit more knowledge. Here’s a neat illustration of how to build a voltage multiplier that can output a positive or negative supply. It is based on a design known as the Cockroft-Walton Multiplier. It’s the add-on housed in the plastic box seen in the image above. It uses diodes and capacitors in an orientation very common for generating high voltages. In fact, the same thing can be found in that high-voltage bulletin board. The place this differs is when it comes to connecting the multiplier to the PSU.

If you look closely you can see one red and one black banana plug jack poking out the end of the plastic container. There is also a pair of these on the other end. The multiplier has been designed so that reconfiguring the inputs and outputs changes how it works. Each jack has been labeled with one possible input and one output. Choose the desired output (DC+ or DC-) and then follow the labels for the rest of the connections.

What can you do with this setup? Check out the clip after the break that shows it powering a lifter.

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The Ultimate Breadboard – A Prototyping Station That Has It All

[Claudio] was working on a homebrew oscilloscope project when he started thinking about how unsuitable a standard breadboard is for a large-scale project. Rather than adding components on top of components until they became what he lovingly calls a “fragile, unforgiving crapstack”, he decided to build himself the Ultimate Breadboard.

He packed so much into his design, that it’s honestly hard to know where to begin describing it. Aside from an appropriately large breadboarding surface embedded in the center of the console, he added a power supply to the left hand side, which sits just below an Avr-Net-IO board. The right side of the console features an Arduino NG, and a pair of level converters. He also added some LED-based VU meters, a couple of 7-segment displays, an LCD display, an analog voltmeter, along with plenty of I/O connectors.

The Ultimate Breadboard might look a bit daunting at first, but it seems like an awesome setup on which to do any sort of prototyping. Be sure to check out the video below for more details and to see [Claudio] give a tour of the device.

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Replacing An Overheating Tablet Power Supply

[Dave] has an ASUS tablet PC with a little problem. The device is charged via the docking connector’s USB cable when plugged into a special wall transformer. The problem is that the wall unit tends to overheat, and is shut down by a thermister inside to avoid permanent damage. The word on the Internet is to drop it in a zipper bag and chill it in the freezer for a bit. Although this works, it’s not the permanent solution that he was looking for. Instead, he hit the parts bin and built his own power supply replacement without buying anything.

The device is simply looking for 12V on the power pin (pin 1) of the USB cable. [Dave] dug through his mountain of unused AC adapters and found one that fit the voltage and current specs of the stock unit. He also grabbed a dusty old motherboard and plucked the USB ports off of the back. A bit of protoboard makes for a good base to connect the AC adapter wires to the ports, which was then covered with one big shrink tube. The result is seen above, and demonstrated in the clip after the break.

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Exposing Some Fake Electronics With Too-good-to-be-true Prices

[Giorgos Lazaridis] needed an AC adaptor for his Canon PowerShot camera. He hit eBay and was excited to find this branded adaptor for just five bucks! It works and, even though it would sometimes reboot his camera if the cord was twisted around in the jack, he was satisfied that it did what it was supposed to.

That is, until one day he observed some very peculiar behavior while taking pictures of a PIC circuit he was prototyping. When holding the camera and putting his other hand near the breadboard one of the status LEDs in his circuit began flashing sporadically. If he was using the camera with batteries instead of the adapter this didn’t happen.

His first instinct was to hook up the adapter to his oscilloscope and see what is happening on the power bus. The signal is incredibly noisy. Shockingly so. [Giorgos] cracked open the case to see what is going on with the power supply circuit inside. You simply must view the video after the break to see the horror-show he found. The board is poorly soldered, components are not properly seated in their footprints, and our favorite is when [Giorgos] points out a squiggly trace which takes the place of the smoothing inductors.

Have you documented your own fake electronic hardware finds? We’d love to hear about them. Continue reading “Exposing Some Fake Electronics With Too-good-to-be-true Prices”

High Efficiency Solar Charger Circuit Tops Off Those Lead-acid Batteries

Make your next project solar-powered with this charging circuit. It’s completely through-hole, and there are no microcontrollers that need to be flashed. If you can source parts and are handy with a soldering iron building this will be a breeze.

Both the maximum system voltage and the low voltage drop out are configurable. After assembly, you just need to attach a regulated power supply to the load terminals. Tune the power supply to the max voltage and turn a potentiometer until an LED comes on, then repeat the process for the drop out voltage. Board artwork for the two-sided PCB and a schematic are available from the page linked at the top. If you’re not into etching your own circuit boards you can buy one for around $10.

[Thanks Murray]

Juice Bridge Powers Your Breadboard In A Snap


[Quinn Dunki] got tired of messing around with wires when connecting things to her benchtop power supply, so she built herself useful little power bridge that plugs directly into any standard breadboard.

The board is small and simple, but quite useful all the same. It was built to power both sides of the breadboard, and it can be easily switched between an unregulated power supply and a regulated 5v supply. An ammeter can be attached to the board via a pair of pins she set aside, allowing her to easily measure the current draw of the entire circuit.

We think her “Juice Bridge” would be very useful to anyone who frequently prototypes on breadboards. In fact, it would be a fantastic beginner project since it involves etching and developing PCBs as well as some simple soldering, while resulting in a handy takeaway tool at the same time.

If you want to build one of your own, [Quinn] has the schematics and Eagle PCB files available for download on her site.