The LM317 is a favorite for many people who want quick, cheap, reliable and ajustable power. It only takes a few parts to set up and it does its job rather well. Sometimes though, you just need a power supply.While there are a million tutorials out there, not many go as in depth as [Phil] does in his 2 newest videos.
Covering everything from the wall outlet to the final output, [Phil] explains each part step by step, stating what it does and the math and formulas behind it all to produce quality results. He then goes over to a working model and reviews each part showing its real output on a oscilloscope, which is very handy if you do not have one yourself.
In the second video he takes that knowledge and builds it all up into a professional looking bench top model with LCD meter readout and varnished paper to complete the front look. If you’re looking to build your first bench supply or want a better grasp on what exactly is happening in the one you have now, you should join us after the break for these 2 quality productions.
Continue reading “Power Up with Knowledge”
Sometimes milestone birthdays can be a bit depressing. 30 is rough, and 40 tougher – but 50…that’s a big one!
[Ryan’s] uncle is going to be turning 50 shortly, and in the interest of good-natured fun, he has constructed a handy birthday countdown timer for his uncle, lest he forget (or tries to avoid) the big day.
The device displays the amount of time left before his uncle’s birthday, playing an audio clip of “Don’t fear the Reaper” when the clock strikes 00:00. This is accomplished by using the MSP430′s internal clock to keep time, while also interfacing with a Nokia 3310 LCD panel to display the countdown timer. The music is provided by the circuit board from a greeting card he gutted for the project, which was wired to the LaunchPad in order to be triggered at the right moment. Everything was crammed inside an Altoids tin, as you can see in the picture above.
Though not overly complicated, it’s a fun little project, and we’re hoping his uncle gets a big kick out of it. Once his birthday has come and gone, [Ryan] plans on converting the piece into a permanent desktop clock for his uncle.
[Drake Anthony] makes building a cutting laser from a PC look easy, and it seems like it actually is. Almost everything you need can be found in a dead desktop unit. The diode is pulled from a DVD writer (16x or faster), with the power supply unit, and heat sinks from the processor and GPU being used as well. You’ll also need a focusing lens (just a few dollars), some thermal glue, an LM317, a resistor, and a pair of protective goggles matching the laser diode’s wavelength.
He fits the diode into the lens, then glues the assembly into a hole drilled through the processor heat sink. A driver is built using the LM317 variable regulator, resistor, power supply, and the GPU heat sink to keep things cool. Check out the video after the break to see the laser cutting tape, burning plastic, and lighting matches. Continue reading “Build a cutting laser from an old PC”
SparkFun has released a breadboard power suppy that can provide regulated 3.3v or 5v. Unlike the supply we saw from adafruit industries earlier this summer, this one is based on an lm317. This small device features on/off switch, voltage selection swith, and appropriately spaced pin headers to plug into both the top and bottom rails of a standard breadboard. Rather build it yourself? Take a look at the schematic provided (PDF).
adafruit industries’ latest product is an adjustable breadboard power supply kit. We’ve seen breadboard supplies before, but like most of adafruit’s kits, this is the best design you’re going to encounter. It uses an MIC2941 voltage regulator instead of the more commonplace LM317. It has a very low dropout which means your output voltage can be much closer to the input voltage. Their example is using 3AAA or a Li-Ion battery for an output of 3.3V. Input can be through a barrel jack or terminal blocks. There is a selection switch for 3.3, 5, and adjustable voltage. Using the adjustment pot you can select an output voltage anywhere from 1.3V to within .5V of the 20V maximum input. The adjusted output voltage will remain the same even if you increase the input voltage. Like all of their kits, you can find schematics, assembly and usage instructions, on their project site.
Every project needs a power supply. As 3.3volt logic replaces 5volt systems, we’re reaching for the LM317 adjustable voltage regulator, rather than the classic 7805. We’ve found four different hobbyist-friendly packages for different situations.
A simple voltage divider (R1,R2) sets the LM317 output between 1.25volts and 37volts; use this handy LM317 calculator to find resistor values. The regulator does its best to maintain 1.25volts on the adjust pin (ADJ), and converts any excess voltage to heat. Not all packages are the same. Choose a part that can supply enough current for your project, but make sure the package has sufficient heat dissipation properties to burn off the difference between the input and output voltages.
Continue reading “Parts: LM317 adjustable voltage regulator”