Misc Hacks

4164 Articles

Even Easier Toner Transfer PCBs

January 12, 2016 by 37 Comments

One of the most popular methods of homebrew PCB fabrication is the toner transfer process. Compared to UV-sensitive films and CNC mills, the toner transfer process is fantastically simple and only requires a laser printer. Being simple doesn’t mean it’s easy, though, and successful toner transfer depends on melting the toner to transfer it from a piece of paper to a copper clad board.

This is heatless toner transfer for PCB fabrication. Instead of using a clothes iron or laminator to transfer toner from a paper to board, [simpletronic] is doing it chemically using acetone and alcohol.

Acetone usually dissolves laser printer toner, and while this is useful for transferring a PCB from paper to board, it alone is insufficient. By using a mixture of eight parts alcohol to three parts acetone, [simpletronic] can make the toner on a piece of paper stick, but not enough to dissolve the toner or make it blur.

From there, it’s a simple matter of putting a piece of paper down on copper clad board. After waiting a few minutes, the paper peels off revealing perfectly transferred board art. All the usual etching techniques can be used to remove copper and fabricate a PCB.

This is an entirely novel method of PCB fabrication, but it’s not exactly original. A few days ago, we saw a very similar method of transferring laser printed graphics to cloth, wood, and metal. While these are probably independent discoveries, it is great evidence there are still new techniques and new ways of doing things left to be discovered.

Thanks [fridgefire] for the tip.

Learning And Failing At Digital Electronics

January 11, 2016 by 36 Comments

[spencerhamblin] is starting his explorations into digital electronics the hard way: reproducing a “simple” IC’s functionality by wiring up a board full of discrete transistors. In this case, the end product is a binary-to-seven-segment decoder built from scratch.

In engineering circles, this circuit is better known as a 7447 BCD to seven-segment decoder/driver, but just using a single chip has little pedagogical value. Building a simple circuit with 39 transistors, 31 resistors, and a handful of diodes is a good introduction to digital electronics, and after two attempts, [spencerhamblin] knocked it out of the park.

The build began with a piece of copper clad board, a bunch of cheap FETs from fleabay, and an incorrect schematic. While the first version of the project looked fantastic with Manhattan-style construction, and jumper wires everywhere, the schematic was fundamentally flawed and [spencer] got a little confused when converting the circuit to a common anode display.

Version two used a more standardized construction. This circuit was plotted in DipTrace, and the resulting PCB was sent off to OSHPark. The build was cleaner, but in capturing the schematic, [spencer] reversed the footprint of the seven segment display. That was easy enough to fix with a few short wires, and after a little bit of work [spencer] had a device that would convert binary to a seven segment display.

Building Triodes With Blinker Fluid

January 9, 2016 by 67 Comments

The triode is one of the simplest kinds of vacuum tubes. Inside its evacuated glass envelope, the triode really is just a few bits of wire and metal. Triodes are able to amplify signals simply by heating a cathode, and modulating the flow of electrons to the anode with a control grid. Triodes, and their semiconductor cousin the transistor, are the basis of everything we do with electricity.

Because triodes are so fantastically simple, they’re the parts most commonly crafted by the homebrew tube artisans of today. You don’t need a glass blowing lathe to make the most basic vacuum tube, though: [Marcel] built one from the light bulb used in a car’s tail light.

The light bulb in your car’s tail light has two filaments inside: one for the normal tail light, and a second one that comes on when you brake. By burning out the dimmer filament, [Marcel] created the simplest vacuum tube device possible. In his first experiment, he turned this broken light bulb into a diode by using the disconnected filament as the anode, and the burning filament as the cathode. [Marcel] attached a 1M resistor and measured 30mV across it. It was a diode, with 30μA flowing.

The triode is just a diode with a grid, but [Marcel] couldn’t open up the light bulb to install a piece of metal. Instead, he wrapped the bulb in aluminum foil. After many attempts, [Marcel] eventually got some amplification out of his light bulb triode.

The performance is terrible – this light bulb triode actually has an “amplification” of -108dB, making it a complete waste of energy and time. It does demonstrate the concept though, even though the grid isn’t between the anode and cathode, and this light bulb is probably filled with argon. It does work in the most perverse sense of the word,  and makes for a very interesting build.

Video Gives You The Basics Of DIY Rotary Encoders

January 8, 2016 by 45 Comments

Is it really possible to build a rotary encoder out of a flattened tin can and a couple of photodetectors? Sure it’s possible, but what kind of resolution are you going to get from such a contraption? Is there any way that you’d be able to put them to work in a DIY project like a CNC router? If you pay attention to the basics then the answer is yes, and [HomoFaciens] wants to prove that to you with this detailed video on homebrew encoder design.

Faithful Hackaday readers will no doubt recognize [HomoFaciens] from a number of prior appearances on these pages, including this recent hardware store CNC router build. When we first ran across his builds, we admit a snicker or two was had at the homemade encoders, but if you watch the results he manages to get out of his builds, you quickly realize how much you can accomplish with very little. The video is a primer on encoder design, walking you through the basics of sensing rotation with phototransistors, and how a pair of detectors is needed to determine the direction of rotation. He also discusses the relative merits of the number of teeth in the chopper; turns out more isn’t necessarily better. And in the end he manages to turn a car wiper motor into a high-torque servo, which could be a handy trick to have filed away.

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“Reverse engineering” a real candle

Reverse Engineering A Real Candle

January 6, 2016 by 19 Comments

[cpldcpu] just can’t leave the mysteries of candles alone. We’ve covered his explorations of candle flicker LEDs before, but this time he’s set his sensors on the real thing. [cpldcpu] hooked a photodiode to his oscilloscope, pointed it at a candle flame, and recorded the result.

The first interesting observation was the candle slowly changed brightness, whether it was interacted with or not. Next he measured the effect when the flame was disturbed by small gusts of air. This produced a bright flicker with an oscillation at 5Hz before returning to steady state, which as [stygiansonic] mentioned in a the Hacker News comment, is a known phenomenon used in flame detectors. Neat! There’s even an equation:

Under normal gravity conditions, the flames have a well defined oscillation frequency which is inversely proportional to the square root of the burner diameter, D, and to a good approximation can be written as f » 1.5/D½, with D given in meters.

[cpldcpu] then compiled his measurements into a series of graphs and ultimately an animated gif comparing the candle steady state, a real candle’s flicker, and the flicker he recorded from a candle flickr LED. It’s surprising how different the fake is from the real thing. You can look at his measurements and code at his github.

[via Hacker News]

The Most Plausible Apollo Moon Landing Conspiracy Ever Devised

January 6, 2016 by 247 Comments

The Internet is polluted with craziness, and there is no better example than YouTube. If you’ve ever wondered what would happen when you give everyone on the planet the power to show everyone else on the planet their innermost thoughts, desires, and insane ramblings, you need only look at YouTube.

One of the biggest offenders of incoherent ramblings is the subject of spaceflight. Simply search ‘space shuttle’ on YouTube, and you’ll find accusations of the crew of Columbia being abducted by aliens. Crazy, incoherent, and somewhat insulting. Accusations of a moon landing conspiracy are unavoidable in the ‘related videos’ section and are similarly filled with videos from people with either a tenuous grasp of reality or too much time on their hands.

A broken clock is right twice a day, a broken calendar is right every twenty-eight years or so, and every once in a while, simply from the volume of videos on the subject, one conspiracy theorist will present a new and novel idea. Here we present perhaps the only moon landing conspiracy theory that makes sense, is consistent with physical laws, and that may actually be true.

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Hack Your Brain: The McCollough Effect

January 6, 2016 by 81 Comments

There is a fascinating brain reaction known as the McCollough Effect which is like side-loading malicious code through your eyeballs. Although this looks and smells like an optical illusion, the science would argue otherwise. What Celeste McCollough observed in 1965 can be described as a contingent aftereffect although we refer to this as “The McCollough Effect” due to McCollough being the first to recognize this phenomena. It’s something that can’t be unseen… sometimes affecting your vision for months!

I am not suggesting that you experience the McCollough Effect yourself. We’ll look at the phenomena of the McCollough Effect, and it can be understood without subjecting yourself to it. If you must experience the McCollough Effect you do so at your own risk (here it is presented as a video). But read on to understand what is happening before you take the plunge.

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