DIY Dust Cyclone A Traffic Cop Would Be Proud Of

April 26, 2015 by Rich Bremer 45 Comments

Sure, having a wood shop is super handy but it also can get real dusty. Hooking up a shop vac to suck up dust coming off a wood-cutting machine works for all of 3 minutes before the vacuum’s filter gets clogged with dust. There is a solution, though, and it is called a dust separator.

A dust separator does just as its name suggests, it separates dust from air. There is a common type of dust separator made in the DIY community, it has a cone-shaped body and is generally referred to as a cyclone-style. [Dror] built his own cyclonic dust collector out of an odd object… a traffic cone. Looking at it now, we wonder why this isn’t much more common!

The dusty air enters the PVC pipe and ends up spinning around the inside of the cone. Since the dust particles have mass, they are thrown to the outside of this chamber as they spin. They lose speed and drop down into the 5 gallon bucket below. The dust-free air then outlets through the top of the dust separator which is connected to a shop vac.

You’ll notice that [Dror] decided to use threaded rod to hold his separator pieces together. While this may seem like overkill, he had tried several glues and could not get any to stick to the traffic cone!

If you’d like to get in on the dust separator action but don’t have a traffic cone, they can also be 3D printed or made from metal.

The Ultimate Tool For Homebrew PCB Manufacturing

April 26, 2015 by Brian Benchoff 37 Comments

While OSHPark, Seeed Studio, and DirtyPCB have taken most of the fun and urgency out of making your own circuit boards at home, there are still a few niche cases and weird people who like to go it alone. For them, [Jarzębski] has created the ultimate homebrew PCB manufacturing solution (.pl, here’s the Google translatrix).

[Jarzębski] is using UV-sensitive photomasks for his PCBs, but he’s not doing something simple like a blacklight to develop his boards. He’s using a 30 Watt UV LED for exposing his boards. This, of course, generates a lot of heat and to mitigate that he’s added a Peltier cooler, temperature sensor, and a fan to cool off this retina-burning LED. 30 Watts will get the job done, considering [Jarzębski] was using a quartet of 4.5W LEDs before this build.

Developing a PCB is only one part of the equation; you need to etch it, too. For this, [Jarzębski] is using a small 1.6 Liter aquarium and four aquarium heaters for dunking 120mm x 120mm PCBs in the tank. There’s no mention of what chemistry [Jarzębski] is using – ferric chloride, cupric chloride, or otherwise – but the heaters and aerator should make etching go very smoothly.

There’s a video (English) going over the rest of the project below.

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Massive Wood Joints With Chainsaw Mortiser

April 25, 2015 by Rich Bremer 21 Comments

One common joinery method used in wood working is the mortise and tenon. A mortise is basically a hole in a piece of wood and the tenon is another piece of wood cut to tightly fit in that hole. The tenon is usually secured in place with either glue or a wooden pin or wedge.

The folks over at [WayOutWest] were building a fence and needed a way to cut a bunch of mortises in 4×4 inch posts to accept 2×6 inch rails. Although they had a chainsaw, trying to cut a mortise with it by hand turned out to be super dangerous because the chainsaw would kick up every time the tip of the blade touched the wood. The team had some parts kicking around so they made a fixture to hold the chainsaw as it is plunged into the 4×4’s.

The contraption’s frame is made from an old scaffolding stand and the slides are just pipes inside of pipes. The chainsaw is bolted to the slide and a lever moves it forward and back. A second lever moves the piece of wood getting mortised up and down so that the mortise can be cut to any width. This is a pretty ingenious build that only cost a little effort and will end up saving a bunch of time mortising countless fence posts.

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Mini Wood Lathe Made Of….. Wood?

April 25, 2015 by Rich Bremer 20 Comments

When someone says ‘wood lathe’ the average person would think of a lathe used for turning pieces of wood into ornate shapes. But what if that lathe was also made of wood. Would that be a wood wood lathe? Instead of wondering the answer to that very unimportant question, young 15 year-old [laffinm] decided to actually build a wood wood lathe from plans he found in a magazine.

As you would expect, a 15 year-old’s budget is certainly not going to be very large. [laffinm] started by gathering plywood scraps left over at construction sites. The lathe bed, head stock, tail stock, tool rest and motor mount are all made from 3/4″ plywood. The tool rest and tail stock have knobs that allow loosening of each part so that they can be moved to any location on the bed.

Out back, [laffinm] made his own live center for the tail stock out of a chuck and bearing assembly that he pulled from an old drill. The tail stock supports were drilled out to fit the bearings which were epoxied in place. The live center and tail stock combination supports the right side of the work piece that is being turned on the lathe.

In the end the lathe came out pretty darn well. We here at Hackaday love projects that make use of recycled parts and this project sure does that as most of the parts were scavenged or obtained for free with the only exceptions a v-belt and some nuts and bolts. If you’d like to see the build process in detail, [laffinm] has a very complete Instructable with 3 build videos, the first of which you can find after the break.

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Review: Transistor Tester

April 24, 2015 by Adam Fabio 84 Comments

Amazon has been getting creepier and creepier lately with their recommendations. Every time I log in, I’m presented with a list of new Blinky LEDs, Raspberry Pi accessories, Arduino shields, and the like. It’s as if they know me. Their customer database paid off when it recommended a $22 transistor / component tester. I’ve been seeing those testers around quite a bit lately. Curiosity got the better of me and my mouse found its way to the “Buy it now with one click” button. Two days later I had a “SainSmart Mega328 Transistor Tester Diode Triode Capacitance ESR Meter MOS/PNP/NPN L/C/R” in my hands.

I’m going to get the obvious out of the way. This thing is built cheap – as cheap as the factories can make it. My particular unit arrived with the LCD flapping in the breeze, hanging on by its flex cable. Fitting the LCD back into the acrylic backlight frame revealed a slightly worrisome twist in that same flex. Thankfully nothing was actually damaged, though I do want to give the flex cable some protection in the future. More on that later. The circuitry was open for all the world to see on the bottom of the tester. The heart of the unit is an ATmega328. Supporting it are a few transistors and a handful of passives.

I didn’t have huge expectations for the tester, but I hoped it would at least power up. Hooking up a 9 volt battery and pressing the magic button brought the tester to life. Since I didn’t have anything in the socket, it quickly lit up and displayed its maker information – “91make.taobao.com”, and “By Efan & HaoQixin”, then it informed me that I had “No, unknown, or damaged part”.

I had a few resistors lying around the bench (doesn’t everyone?) so I put one in. The tester read it as 9881 ohms. Sure enough, it was a 10K 5% resistor. Capacitors – ceramic disc, electrolytic, and surface mount all worked as well. The tester even provided ESR values. The real test would be a transistor. I pulled an old 2N2222 in a TO-18 metal can, and popped it in the tester. The damn thing worked – it showed the schematic symbol for an NPN transistor with Collector, Base, and Emitter connected to Pins 1,2,and 3 respectively. Flipping the pins around and re-testing worked as well. The tester showed hFe as 216, and forward voltage as 692 mV, both reasonable numbers for a 2N2222.

The tester worked surprisingly well – it was able to correctly identify BJTs, FETs, even esoteric parts. The only thing it balked on was a linear voltage regulator, which showed up as two diodes. Regulators are a bit more than a simple device though, so I can’t blame the tester there. The values returned were all reasonable as well. While I don’t have a calibrated lab to check against, the numbers lined up with my Fluke meter.

So what exactly is driving this little tester? There are about 20 versions of it on the market, all of them from China. 91make is a seller on taobao.com, often referred to as “China’s ebay.” 91make’s front page features no less than 7 versions of the transistor tester, with various cases and LCDs. Some digging turned up the history on this device. It turns out the transistor tester is an open source hardware project (translated) originally created by [Markus Frejek], and built upon by [Karl-Heinz Kubbeler] and a number of others. The Subversion repository for the project shows it is quite active, with the most recent check-in only a few hours ago. The project is also well documented. The English PDF is 103 pages, explaining theory of operation, the circuit itself, and the software. The document even explains some of the shortcomings of the Chinese versions of the tester, including using a zener diode where the original schematic calls for a precision 2.5V reference. Yes, it will work, but it won’t be as accurate as the original.

The devs also don’t officially support the clones which I can understand, considering the quality and changes in design each manufacturer is baking in to their own version. There is a huge thread on the EEVblog forum covering these testers. Some can be modified to be closer to the official version. In fact, with an ISP tool the intrepid hacker can update the firmware to the current rev from [Karl-Heinz’s] repository.

So the final verdict on this tester is that it is a thumbs up with a small caveat. These testers are built down to a cost (and that cost is as close to zero as possible). They’re great for sorting parts, but they’re no substitute for a higher quality measuring device. I’d also love to see a version that supports the original developers.

Interactive Software To Solve Crosstalk Problems

April 20, 2015 by Bil Herd 4 Comments

A link to this video demonstrating PCB cross-talk ended up in my mailbox the other day as I tend to stay on the mailing lists of the some of the high end CAD companies. There are some really interesting and powerful “mega-tools” that do things like plot noise density for decoupling analysis and extremely high speed timing analysis, though the costs of these tools are commensurate with their capabilities. This one is part of the Mentor Graphics PCB Simulation software.

The tool shown does the math needed to predict the induced voltage noise (cross-talk) generated by the proximity of noise sources to the noise susceptible elements, and the tool does so interactively. This is remarkable… in the past we would calculate some examples of trace width, spacing, and the type of signals involved, and then generate some rules of thumb that we tried to apply during the layout process. It was an educated guess that was sometimes not as close as we would have liked.

Virtual Scope Showing Predicted Crosstalk — Virtual Scope Showing Predicted Cross-talk

The cool part of this software is the interactive nature. One can learn the effects of placement on cross-talk in real time, which helps build an intuitive understanding.

I will add the standard disclaimer that a tool is exactly that, a tool, and it only represents an approximation of real life at best. It’s tempting to design to the tool itself, and many engineers have learned the limitation of a tool the hard way. Instead think of the tool as another opinion, or as mentioned, a learning aid to gather an intuitive feel for the effects of placement on circuit performance.

“Easy Bake” Vacuformer

April 17, 2015 by Mike Szczys 31 Comments

One of our favorite things about Hackerspaces is people tend to spend a lot of time building tools, or repairing/upgrading older ones. This is a case of the former. The vacuum former.

[Adam] wrote in to tell us about this vacuum forming machine which he and few other members built for FizzPOP, a hackerspace in Birmingham, England. The device is used to suck hot sagging plastic around a mold. This is accomplished in two parts, the vacuum table and the heating mechanism to put the sheet of plastic into that sagging state.

The vacuum part of these tools has been easy to DIY for a long time. Pegboard makes for a very good table surface, with some type of vacuum motor (usually a shopvac or two) in an enclosure below the surface. This design adheres to that common formula.

On the other hand, the heating mechanism is more difficult to solve. The plastic is unwieldy and fragile when hot so a frame is very common. Following the example of commercially available models, the FizzPOP crew built a frame that slides along four vertical rails (envision table legs) extending above the vacuum surface. These legs also hold up the heating element. Often this is a nichrome wire array, but not this time. They went with an array of 70 halogen bulbs in a 10×7 orientation. A PCB was milled for each, with a system of bus-bars connecting them all. The trial run showed that the intensity of the bulbs made hotspots directly below each. But a bit more testing helped them solve the issue by keeping the frame further from the array in the heating phase.

The team’s 13-seconds of fame are found after the break. A black sheet of High-Impact Polystyrene (HIPS) is formed around a compilation of tools spelling out the name of the hackerspace.

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