Dummy Loads And Heat Sinks

August 6, 2010 by Mike Szczys 21 Comments

In [Dave’s] latest episode of the EEVblog he takes a look at constant current dummy loads. These are used to test power supply designs and instead of just chaining resistive loads together every time he’s decided to look into building a tool for the job. What he ends up with is a reliable constant current load that can be dialed anywhere from 1.5 mA up to just over 1A. There’s even an onboard meter so you don’t have to probe the setting before use.

It may look like he sent his design off to the board house for production but that’s actually a re-purposed PCB. In walking though his junk-box assembled dummy load [Dave] shares some great tips, like using multiple 1% resistors instead of shelling our for one large and accurate power resistor. But our favorite part comes at about 12:00 when he takes us through some rough math in calculating heat sinks. We’ve always just guessed, but like any good teacher, [Dave] explains the theory and then measures the actual performance taking the guesswork out of the design. See for yourself after the break. Continue reading “Dummy Loads And Heat Sinks” →

Hackaday Links: February 14, 2010

February 14, 2010 by Mike Szczys 15 Comments

$30,000?

Is it art or is it a puzzle? Well, it functions as a game but it’s certainly a work of art and priced accordingly. The Superplexus was featured in Make Mazine and Hammacher Schlemmer sells it for thirty grand (you can’t just click to add it to your cart though). Think of the work that went into developing this! [via The Awesomer]

Rollable Display Update

[SeBsZ] continues work on his rollable display matrix. He’s got twenty five controller boards now and has them working as a matrix. We originally covered this in January but now it’s much easier to see how this can be made portable by mounting it on fabric or canvas. Check out the demo video if your interested.

Security testing suite

BackTrack 4 final has been released. If you didn’t like it when it was rough around the edges, you should give it another try. This lean and mean Linux ditro is made for security testing and is approachable for noob and pro alike. [Thanks Steve]

Power on the go

[Csae] uses this portable power center to fire up some studio strobes outside. It consists of a case, an uninterruptible power supply, and a couple of extension cords all hacked together into one. At first you might think this is a bit ghetto but it’s portable and it does what is intended.

Happy Valentine’s Day

Giving this LED-heart adorned shirt as a gift is sure to make your Valentine head for the hills. This project’s a few year’s old, but gawdy T-shirts never go out of style, right?

‘tiny’ Power Supply Monitor

February 9, 2010 by Mike Szczys 13 Comments

[Manekinen] built a power supply monitor based around an AVR ATtiny13. Voltage and amperage are displayed on a 16×2 LCD character display (we’re not sure what the third number is… samples per second?). This is no small feat considering that the tiny13 is an 8-pin chip. He makes it happen by using the pins for both LCD control and ADC input. To make this happen the HD44780 compliant display is used in 4-bit mode. Check out the video after the break and hit up the non-translated page if you want to download the source code and PCB artwork. A note of warning, he’s using the RESET pin for I/O which means once you burn the fuses you’ll need a programmer that has High Voltage Serial Programming capabilities if you want to reprogram the chip. Continue reading “‘tiny’ Power Supply Monitor” →

Jump Start Your Car With Sega Parts

October 5, 2009 by Mike Szczys 47 Comments

sega_jump_start

[Jenn’s] family is a single-car household. Because of this, it’s a little more difficult to get a jump start when the headlights run down the battery. Not wanting to ask the neighbors for help, her husband [Richard] decided to come up with his own solution.

Rummaging through the parts on hand, [Richard] went with his old friend Sonic the Hedgehog. He used two 12-volt, 1 amp Sega Genesis power adapters in parallel hooked up to a 12 volt, 3 amp power supply. The end result is a 12-volt 5 amp source hooked to the car’s electrical system and used to get their road machine started.

We have enjoyed some of [Richard’s] offerings in the past, such as Super Nintoaster and the Super Genintari but this is a bit less… eloquent. A few questions do come to mind. First of all, is this the best way to use parts of your 20-year-old gaming system? How many amps does your average car starter pull down? And finally, what kind of issues are we looking at with the lead acid battery under these conditions? Weigh in on the conversation in the comments.

Dual Voltage Power Supply

September 14, 2009 by Mike Szczys 29 Comments

dual_regualted_power

[Melanie] had some time this weekend so she whipped up a dual voltage power supply from parts on hand. This design plugs right into a breadboard and, unlike the last breadboard power supply we saw, provides two voltages at one time. 5v is delivered to one power bus while 3.3v goes to the other. Her design uses two linear low voltage drop regulators from the LF00 family (PDF datasheet) to accomplish this. Nice work!

Learn From The Ice Tube Clock

August 25, 2009 by Mike Szczys 22 Comments

Looks like they’re at it again over at Adafruit. This time they’ve produced a clock that looks more like it should be attached to a munition rather than cruising bedside. But, geek-cred aside, there’s a lot to be learned from their design. Like we’ve grown to expect, they’ve put together some good documentation on their choice of components.

Start off by taking a peek at their 5v power regulator. There is an extra diode on the output side that prevents reverse current from the 3v backup battery. The AVR ATmega168 that controls the clock is used to detect loss of power and quickly shift to the battery backup. They’ve also used the microcontroller as a boost converter for the high voltage VFD, a nice trick we’ve seen before.

[Thanks pt]

Bench Power Supply Adapter

August 24, 2009 by Matt Schulz 14 Comments

psu_adapter

Every electronics workbench could benefit from having a bench power supply. Converting a PC power supply works, but often, it involves splicing wires and limits the supply to only bench use, and building one from scratch is definitely an undertaking. To counter this, [silic0re] and his father came up with a detachable adapter that simply plugs into the existing connectors. The adapter provides posts for four different voltages and can be built in no time. It’s nice to see a solution that will let you use any power supply laying around without having to worry about the dangers of opening it or cutting it up.

[Thanks silic0re]