If you work with electronics at any skill level you need juice. [Jon] has a great, and clearly worded tutorial about Wall Wart Power Supplies with pretty much everything you need to know about those little black boxes hanging off of your outlets.
The whole thing starts off with the basics like transformers, rectification smoothing and regulation, then moves on to the different basic types, dedicating a page to linear, regulated and switching types, giving output performance charts under different situations.
Also included is a run-down of DC barrel jack structure so you get the right plug every time, wall wart type identification, a random sample comparison test, and a good selection of formulas to even keep the old hats reading along. Although you might want to set aside a little time at 9 pages and some Q/A in the comments, it might take a moment to read.
[Marc] is pretty unsatisfied with hard drive docking stations as a whole. He says they are typically slow and unreliable, causing him all sorts of grief while he is troubleshooting a questionable hard drive. He decided to take some of the mystery out of the troubleshooting equation and built a standalone SATA power module.
Aware that SATA drives require 5v and 12v for operation, he disassembled one of his docking stations to see how it provided both voltages. He discovered that it used a simple PWM buck converter and decided to replicate it in the smallest space possible. His plan was to use a standard 12v wall wart to power the circuit, passing that 12v straight to the drive. A simple voltage step-down circuit would be built to provide the required 5v.
[Marc] reports that the power adapter is performing nicely, and he is quite happy with the size as well. He says that one major benefit of this sort of adapter is that it can be used to power any SATA drive, not just hard drives. He does mention that if he built another one, he might consider regulating the 12v output as well, so that he can power the adapter with a laptop power supply instead of a separate dedicated wall wart.
What can you do to make sure your system is running as efficiently as possible? Take a page out of [Mux’s] book, who went to great lengths to measure and adjust his system for ultimate efficiency (translated). What he ended up with is 8.5 Watts of consumption at idle and about 50 Watts under load. Luckily he posted a six-part series with all of the details.
Some of the changes he made were in software, like reducing voltage to certain hardware by adjusting BIOS settings, and installing display drivers that put the screen into the proper sleep mode. Others were hardware changes like swapping out the power supply with a hacked PicoPSU and removing unnecessary parts from the motherboard like the MAX232 com-port chip. Looks like we need to audit our always-on MythTV box and see if we can apply any of these power-saving techniques.
New Years celebrations tend to get bigger and bigger every year for most people, and [Brian] takes no exception. In order to top his lighted tree of a few years ago, he has concocted a 40’x40′ set of Seven-Segment displays made out of Christmas lights, hung from nearby trees. These displays would start counting down the minutes an hour before the ball drop, and be synchronized with music. Also in the spirit of a New Years party, the music he has chosen is in the form of a Power hour. The control board [Brian] is using also comes with two extra outputs, which he plans to use for the most exciting possible additions: Fireworks and Flamethrowers.
Be sure to check back after New Years to see a video of the device in action. Be sure to Hack, Drink, and Party Responsibly out there.
[Riley Porter] posted a picture of his EvalBot USB power hack. In the photo above we’ve put a box around D6 and D7. The development board ships with a 0 Ohm resistor in the D7 location, patching in power from the USB-B connector labeled USB DEVICE. He found that by moving that resistor to D6 he can power the board from the USB-B connector labeled ICDI.
That connector is the In-Circuit Debug Interface. TI sent us an EvalBot bundle so we pulled it out and tried it ourselves. If you plug in the ICDI it doesn’t power the board, and no USB devices register. Shorting the D6 pads changes this and the following USB device registers:
Bus 002 Device 062: ID 0403:bcd9 Future Technology Devices International, Ltd Stellaris Evaluation Board
So it looks like you need to have two USB connections or be using batteries in order to program the board via USB. The uC/OS-III hardcover book that ships with the EvalBot bundle includes board schematics. We took a look and were surprised to see that they show diodes installed on both pads. Rev A of the online schematics have been corrected, showing an omitted diode on D6 and the 0 Ohm resistor on D7. Images of both schematics are included after the break.
It would have been nice to see a selector switch installed here to give you a little more flexibility when prototyping.
Continue reading “Moving a resistor for EvalBot power when programming”
[Warrior_Rocker] pulled off his own Apple Studio Display hack by removing the cable and adding ports. As we saw in Wednesday’s post, these displays use a cable with a proprietary connector that combines DVI, USB and Power. Instead of altering the cable, [Warrior_Rocker] removed it completely. By wiring up a standard barrel jack for power, a USB type-B socket, and a DVI port, he can now use standard video, power, and USB cables to connect to the monitor.
This project was actually submitted to us on May 25th and we missed it. It’s sad that sometimes tips fall through the cracks, and we’re sorry that we missed this particularly well-executed hack. [Warrior_Rocker] wrote in asking why his project didn’t qualify after seeing the similar post on Wednesday. So please don’t take it personally if your project doesn’t get posted. If you think it fits right in here at Hackaday and haven’t heard anything after two weeks or so, consider sending to us again.
This programmable power supply is the perfect addition to your bench tools. [Debraj Deb], who previously built a whole house power monitor, designed this build around a PIC 18F4520 microcontroller. The desired voltage is set with an attached keypad, resulting in a digital output on the 8-bits of port D. The port connects to another protoboard with an R-2R digital-to-analog converter resulting in the target voltage. A set of transistors amplifies the current and a power transistor then takes care of the final output. After the break you’ll find two videos, the first walks us through the hardware and the second demonstrates the device in action, along with measurements of its performance. This certainly provides a lot more functionality than an ATX power-supply conversion.
Update: A big thanks to [Debraj] who sent us a code package as well as the schematic (PDF) used during testing. We’re having trouble getting the code package up for download right now. Check back later, hopefully we’ll have it up soon.
Continue reading “PIC programmable power supply”