Good, workable test gear is key to enabling our hobby. In this post we will discuss where to procure it at rock-bottom prices, what to look for, how to fix it, and how to tailor your laboratory practices around gear that may not be reliable.
We are lucky to be living in an era with plentiful high-quality test gear. Since the Second World War, surplus test gear has been in abundance at low costs enabling hobbyists, innovators, and academics to experiment and build great things. If you are willing to think before you measure you can save serious amounts of money and have a professional laboratory in your home.
Where to buy
The obvious answer is eBay, but the deals on test equipment are at the hamfests. Don’t be fooled by the name. Hamfests sell much more than amateur radio equipment. Hamfests are swap meets where hobbyists trade electronics of all kinds. Check out the ARRL hamfest calendar to find the next local one near you! I suggest you arrive early, however. The culture of hamfests tends to favor showing up as soon as the doors open and leaving about two hours before the official end. The early bird gets the worm!
Photos from a local hamfest showing an abundance of test gear (photos courtesy of Scott Pastor KC8KBK).
Continue reading “Think Before You Measure – Old Test Gear and Why It Is Awesome”
Wooden pallets are a versatile and widely-available starting point for a multitude of projects. Best of all, they can usually be acquired free of charge. But choose the wrong kind of pallet and you could end up paying dearly. [Eric] has compiled a great deal of useful information about pallets that will help you find ideal candidates and prepare them for whatever project you have in mind, be it a coffee table or a backyard roller coaster.
Pallets come in several styles and loader configurations. Some are made with space between the boards, and others are closed. If you take nothing else away from his article, just remember to look for plain, untinted pallets with no markings and you’ll be fine.
No markings means the pallet was used domestically, so markings aren’t required. Marked pallets from abroad should feature the IPPC logo as well as a treatment code indicating the method used on the material. Debarked (DB), heat treated (HT), and pallets with the European Pallet Association logo (EPAL) are all safe choices. Pallets labeled (MB) were treated with methyl bromide, which is a poisonous fungicide. Colored pallets should be avoided as well. If you find one in a cool color, take a picture of it and find some paint in a similar hue.
Safe pallets can be had from many places ranging from hardware stores to feed and tack supply stores. Find someone you can ask for permission to take pallets—they might even help you load them. Keep some gloves in your trunk to avoid splinters.
If you get into more complicated PCB design, you’ll find the need to drill tiny and accurate holes much more often. Wouldn’t it be nice to have a precise way of doing that? Maybe even something as simple as strapping a $10 USB digital microscope to it?
That was [mlerman’s] thought anyway, and from the looks of it, it seems to work quite well! If you already have a PCB drill press then it’s just a matter of installing the microscope opposite the drill — align it to the center point with some cross hairs and boom you’re in business.
But if you don’t yet have a PCB drill, [mlerman’s] got you covered there too, as he explains in great detail how to modify a cheap drill press into an inverted PCB drill press.
Wait, why is it inverted? Besides making more room for the USB microscope to sit, it also ensures the microscope lens doesn’t get covered in the PCB fairy dust that would fall on it if it were in a normal orientation.
Don’t throw out that old printer! Not that you would, but even if you’ve already scavenged it for parts, you can use the shell and the rollers to make a rock/coin/what-have-you tumbler. If your printer is part scanner, it might end up looking as cool as [th3_jungle_inv3ntor]’s. You’ll have to laser-cut your own arachnid to supervise from above, though.
Somewhere between having an irreparable printer, being inspired by another tumbler, and the desire to make a mancala set for his sister-in-law, [th3_jungle_inv3ntor] was sufficiently motivated to get out his hacksaw and gut the printer. He used the main paper roller and its motor to do the tumblin’, and a smaller roller to help accommodate different jar sizes.
Aside from adding those sweet blue LEDs, he wired in a toggle switch, a speed control pot, and an LM317 to govern the tumbling rate. Unfortunately, the rocks in [th3_jungle_inv3ntor]’s town are too soft and crumbly, so he can’t make that mancala set after all. But hey, (almost) free stuff tumbler.
No dead printers lying around? If you have a drill and a vise, you could always make a tumbler that way, and nothing is compromised but the peaches jar.
We must admit to wondering how Adafruit’s [Becky Stern] gets anything done with those fingernails of hers. They’re always long and beautifully painted without any chips, dings, or dents. As it turns out, she uses UV gel nail polish. It’s much more durable than standard air-dry polishes, but it requires UV light to cure. [Becky] bought a lamp to use at home, but it’s very bulky and must be plugged into the wall. She knew there was a better way and devised her DIY UV mini manicure lamp.
She really thought of everything. The open source 3D-printed enclosure includes a small compartment in the top for cuticle sticks, emery boards, and tweezers. The Li-poly battery is rechargeable over USB in conjunction with Adafruit’s PowerBoost 500c. The lamp itself is made from 30 UV LEDs and 100Ω resistors. [Becky] lined the inside of hers with silver sticky paper to help distribute the UV light evenly.
You know, this can also be used to erase EPROMs or to cure small DLP 3D prints. Do you have another use for it? Tell us in the comments. Introductory and partially hyperlapsed video after the break.
Continue reading “DIY UV Lamp Is the Cure for Nails and More”
[Shane] needed a UV exposure box to help speed up the process of making PCB’s at home. Not wanting to spend a few hundred on one, he decided to design and build his own, using a planter box!
Why a planter box? To be honest, it was simply the first opaque container [Shane] found, so he decided to base the design around it. Inside the planter box are two 15W fluorescent daytime bulbs which output a similar amount of UV to normal sunlight. A mirror is placed below them to help reflect all the useful light out of the box. A pane of glass was cut to fit on top of the planter box, giving you a nice surface to place curing PCB’s on.
All in all, it’s a pretty simple and inexpensive method to make your own UV exposure box. We’ve also seen it done before using UV LEDs and IKEA picture frames — just make sure you don’t start tanning your hands while you’re working!
[Stephen] doesn’t have the luxury of readily available hot water in his apartment, and since he’s just renting he didn’t want to buy one of those instant powered units, so he decided to go ahead and build his own!
He’s using a submersible 1000W immersion heater in a 2.5 gallon water container which has been mounted high up in his bathroom to let gravity do the work for actual shower. It’s not quite an instant shower unit as the water needs to heat up like a kettle before being used — this takes about 4 minutes to hit the optimum temperature.
The current shower head installed drains the tank in about 2.5 minutes, which might not seem like much time for a shower, but let’s be honest — we could all probably cut back our shower time and save some water for the environment! Something one of our Hack a Day Prize entries is hoping to solve through music!
Continue reading “Homemade Hot Water Shower Might Shock You”