If you ever watched MacGyver as a kid, you know that given any number of random objects, he could craft the exact tool he would need to get out of a sticky situation. If he ever made his way into the medical research field, you could be sure that this test for Acute Pancreatitis would be among his list of accomplishments.

Designed by University of Texas grad student [Brian Zaccheo], the Acute Pancreatitis test seen in the image above looks as unassuming as it is effective. Crafted out of little more than foil, jello, and milk, the test takes under an hour to diagnose patients while costing less than a dollar.

The test works by checking the patient’s blood for trypsin, an enzyme present in high concentrations if they are suffering from pancreatitis. Once a few drops of the patient’s blood is placed on the gelatin layer of the test, it is left to sit for a bit, after which sodium hydroxide is added. If elevated trypsin levels are present, it will have eaten through the gelatin and milk protein, creating a pathway for the sodium hydroxide to reach the foil layer. If the foil is dissolved within an hour, a circuit is formed and a small LED lights up, indicating that the patient has acute pancreatitis.

The test really is ingenious when you think about it, and will be a huge help to doctors practicing in developing countries, under less than ideal working conditions.

[via PopSci via Gizmodo]

Occasionally when a device breaks, the defect is obvious. Whether it is a blown fuse or a defective capacitor, generally the easy to see stuff is easy to fix. When a problem is more subtle, or when doing some more advanced tasks like adding functionality to a device, greater knowledge about a circuit board is required. While there might be details hidden in lower levels of PCB, often just knowing the mounted components and layout of the outside layers can be enough to create a rough schematic of a device. [Throbscottle] has put together an excellent guide for procedurally breaking down a photo of a board and turning it in to something useful. The guide utilizes some open source image processing software such as the GIMP, Inkscape, and Dia, all of which are widely available. Keep in mind this reverse engineering can be a time consuming process, but will almost definitely reward those patient enough to work through it.

[Thanks to everyone who sent this in!]

Who would have thought that some corn starch could be made into toner transfer paper? We’re not sure of the advantages (perhaps its cheaper?), but if you have a lot of time or just love to get sticky [Matthew Sager] shows the proper method for making the paper, printing, and then etching a PCB.

If you’re just getting started making PCBs, we recommend you check out these DIY circuit etching videos to get a better grasp on the printing and etching steps.

The Atari 2600 pause circuit is now available in a kit form. We saw this pause method back in February and the kit uses the same circuit. We don’t really need a kit for this, the board is very simple to throw together. But we do appreciate the detailed installation instructions (PDF) that accompany it. After all, you don’t want to kill you classic gaming rig with a botched install.

[Thanks CPUWIZ]

An accurate drill press is an essential tool for making your own through-hole printed circuit boards at home. Reader [Josh Ashby] offers up a solid design using scrap bin materials.

A major issue with PCB drilling is that even the slightest horizontal play will snap the delicate carbide drill bit. Hobbyist-grade tools such as Dremel’s drill press attachment are usually too sloppy for this task, while a more precise instrument might set you back a couple hundred bucks.

[Josh’s] design uses a nylon “sled” moving vertically in an aluminum u-channel track. Most of these materials were salvaged or were acquired inexpensively from a local hardware store, and assembled in less than a day. Surprisingly, this low-tech approach has proven sufficiently smooth that he’s yet to break a bit while drilling. And the entire setup, including the knockoff Harbor Freight rotary tool, cost less than the wobbly name-brand accessory alone.

[David Terrill], whose exploits we have covered before, has shared with us his techniques for building circuits without a prototype or bread board. [David] managed to incorporate a Dual D flip-flop at the heart of the circuit, as well as an impressive number of transistors, diodes, and other passive components. Unfortunately, the circuit diagram is a little low resolution to really make out the real function, but based on the components, our best guess is a two-output blinking circuit. Maybe for an encore, someone out there will build a circuit built entirely around a battery so that it can be a self-contained system.

Let us know if you have a better copy of this schematic, or a guess at what the circuit does!

Circuit-bending blog GetLoFi has posted the best tutorial yet on home-made printed circuit boards using the toner transfer method.

We’ve covered homebrew PCB fabrication techniques about a billion times before. What sets this tutorial apart is that it collects many bits of knowledge otherwise scattered all about the web, and then depicts the entire process on video, from initial printing to cut PCB…because reading about it versus seeing it done are two different things entirely. They give a number of immensely useful tips throughout: choice of materials and where to get them, tools and techniques, and dispelling several myths about these methods (for example, they’re adamant about not using acetone to clean toner from the PCB). Well worth the 30 minutes to watch. If that’s too much and you’ve been stuck on just one part of the process, the tutorial is in three segments.

Trimming finished boards on a paper cutter? Who would’ve guessed?

[via Make]

Pulsar Professional FX has a neat tip on their site for getting a really even toner transfer when making your own PCBs. First, the PCB is cut to size, and the paper is tacked to the board. Then, the PCB is placed paper up onto a dowel and rolled back and forth with the iron. Since the board bends slightly over the dowel the toner sticks evenly to the copper. After that, just remove the paper as usual and etch with your preferred method.

Etching a printed circuit board generally takes a bit of time and uses a lot of etchant. [TechShopJim] posted a method that uses a sponge to reduce the amount of etchant used while speeding up the entire process. First, a resist is applied using either a sharpie or the toner transfer method. Using gloves to handle everything, he soaked a sponge in ferric chloride and continually wiped a copper-clad board until all the exposed copper was removed. This technique moves the etchant around more, keeping “fresh” etchant closer to the copper. If you can’t procure ferric chloride, you can also use our method that uses 2 household chemicals: hydrogen peroxide and hydrochloric acid.

[Rhys Jones] has been working with the RepRap team to develop a way to print circuit boards. The machine first prints the plastic substrate with channels for the metal to be deposited into. They adapted their pinch wheel feeder to work with solid core solder (flux creates a mess). The extruded solder’s specific heat isn’t hot enough to melt the plastic. They made a video (embedded below) of their test piece: an optical endstop. The team has also been experimenting with decoupling the feed mechanism from the extruder.

Many people use protoboard and point-to-point wire everything, but needing multiple copies of the same circuit is the reason that forces many away from using protoboard. After making your first circuit board, you might not point-to-point wire anything again!

For your first circuit board, one goal is to keep the circuit single sided so you can etch using single sided copper clad. This will allow you to gain some experience before moving on to double-sided. If you need topside traces, simply run a few jumper wires on the top. There are many complete circuit layouts you could try like the Hack a Day design challenge winner.

Here is a list of materials you will need to produce a single-sided board. With the exception of the copper clad and PCB drills, everything on this list is easily obtained at your local store.

Materials: Muratic acid, common household hydrogen peroxide, safety goggles, good quality magazine pages (cut to 8×11), laser printer, single sided 1 ounce copper clad, a plastic container the board will fit in, soft plastic brush, clothes iron, lacquer thinner, rubber gloves, paper towel, tin snips, drill or rotary tool, PCB drill bits, Scotch Brite scrubbing pad, good ventilation, 5-gallon plastic pail full of water.

Now, here is how you do it:

Print the bottom side layer on a piece of paper from a high quality magazine. Use one actual page from the magazine, the thicker and shinier the magazine paper the better, but do not use the cover. You must use a laser printer, not an inkjet. If your printer uses ink cartridges and not toner cartridges, it will not work. If you do not have a laser printer, you can work around this by printing to white paper and using a photocopier set to the darkest setting to copy the layout to the magazine paper. If the paper jams in the printer, you are not using a thick-enough magazine page. Again, do not use the magazine covers, as they do not work.

Magazine pages are used because they work well, and they are cheap! The reason they work is because the paper is very glossy and the toner does not adhere well to the glossy pages. The printing used on the magazine page is ink and it does not come off, but toner does. Toner is actually a plastic polymer, and different toners may yield varied results. In our experience, a genuine HP toner cartridge was used with great success; an Office Max brand yielded poor results. The sole purpose of the toner is the protect the copper below it from etching away, you only want the uncovered areas to etch.

Next, wash your hands to remove any oils. Keep handling to a minimum once the pages are printed and do not touch the laser printing with your fingers; this could get oils on the printing. Keep pages as flat as possible.

Very carefully, remove the copper clad from the packaging. Do not touch the copper surface for the same reason as above. You can cut the copper clad to size using a tin snip if needed. Use the Scotch Brite scrubbing pad to gently buff the surface (Scotch Brite is a popular brand of of plastic scrubbing pad meant to emulate steel wool). Do not use steel wool because it will embed steel into the copper. Clean off the residual dust with a slightly damp paper towel.

Find a hard, very flat, sturdy, heat resistant surface. Empty the water out of the clothes iron and set the iron on the hottest setting. Allow the iron to get hot.

This is both side of a piece of copper clad. Place the blank side facing down and copper side facing up. Align printing/paper onto copper clad board with the printing facing the copper. Do not allow it to move.

Firmly press the iron onto the back of the magazine paper, sandwiching it between the copper clad and the iron. Pressing hard without moving the iron, hold the iron perfectly still for one full minute. Do not move the iron at all during this minute, and push hard, really hard!

Then, for four more minutes, slowly move the iron around making sure to put a lot of pressure on the paper, but not allowing the paper to slide on the copper. When done, let the board fully cool before you move it at all. This will allow the toner to adhere to the copper and prevent you from being burned.

Put the board in cold water and let soak for five minutes. After five minutes, try to peel the wet paper from the board leaving only the toner/print from your laser printer. Only the toner should be left adhering to the copper. If the paper does not come off easily, let it soak in the water for a while longer. If necessary, rub with your finger to remove any paper, leaving only the toner. It’s ok if there are a few excess paper fibers stuck to the toner.

If you find not every trace adhered to the copper clad or it is misaligned, use lacquer thinner and paper towel to clean the toner from the copper board and start over. If the traces look good then move on. Inspect the traces carefully, however, because what you see now will be your finished product.

In a well-ventilated area with a fan, add 2-cups hydrogen peroxide to a plastic container. Gently pour in 1-cup Muriatic acid, to create the etching solution. Always wear goggles, gloves, and do not inhale the fumes. Do not use any metal containers, measuring cups, stainless steel sinks, or tools with this mixture as this mixture will aggressively etch metal. Acid safety, think “triple A”, for Always Add the Acid, it’s whatever is in the container that will end up splashing. This etching solution, while made with common chemicals, should command respect. It is dangerous to yourself and surroundings, treat it with respect. Ferric Chloride is another common etching solution, it is not a safer solution to use, both are equally dangerous.

Put the board copper side up in the plastic container filled with etching solution. Use a soft plastic brush to gently wipe the board. You will notice the copper begin to dissolve. It takes about 3-4 minutes to get all the exposed copper dissolved. You just have to watch to make sure it is gone in all areas between the traces. Do not leave the board in the etching mix for too long as the traces will dissolve under the toner that is protecting them.

Use lacquer thinner (paint thinner and acetone do not work well) and a paper towel to remove any toner left on top of the copper traces.

Tinning prevents the copper from oxidizing, which can make it hard to solder to in the future. If you choose, you can tin all the traces with solder and a soldering iron now. This actually makes drilling much easier because it helps to center the drill bit. Make sure to clean off excess flux if you do this. You could use Tinit to chemically plate the copper. Here is a different tutorial describing its use.

Drill all the holes for the through-hole parts using the correct size PCB drill bit and rotary tool. Drill large mounting holes with a normal drill. PCB drill bits are carbide and made to drill through fiber glass that would quickly dull standard bits. There are a few very common sizes of bits and these are often sold in packs. We use .0260″ for IC holes and .0310″ for resistors and caps.

Print out the top side silkscreen layer on magazine paper and iron this onto the top side, using the same processes as above. Again, run under water and peel off the paper. Now you have the component ID’s on the top side.

Here is a different video using essentially the same method:

You can make really nice PCBs of your own circuit design using this simple method, and we look forward to seeing your future projects using this method coming in on the tip line. Look for more How-Tos like this one in the How-To category.

The project uses a 5W blue LED, the aforementioned bulb, and a 6V battery pack loaded with 3 AAA batteries. The battery pack and the lights are all attached to a small section of perforated board. Duplicating this project should be easy and provide a very bright LED, but to make a 5W LED shine its brightest, a larger bulb and a heatsink will be necessary.

The Bent Festival for circuit bending is coming up soon if you’d like to see more. You can also check out these links for more information on circuit bending.

The session ended with [Thom Robertson] showing off the Weird Sound Generator he built and his GHX software for playing real music with a Guitar Hero controller.