A Tiny Chemistry Lab

November 8, 2024 by Bryan Cockfield 12 Comments

While advances in modern technology have allowed average people access to tremendous computing power as well as novel tools like 3D printers and laser cutters for a bare minimum cost, around here we tend to overlook some of the areas that have taken advantage of these trends as well. Specifically in the area of chemistry, the accessibility of these things have opened up a wide range of possibilities for those immersed in this world, and [Marb’s Lab] shows us how to build a glucose-detection lab in an incredibly small form factor.

The key to the build is a set of three laser-cut acrylic sheets, which when sandwiched together provide a path for the fluid to flow as well as a chamber that will be monitored by electronic optical sensors. The fluid is pumped through the circuit by a custom-built syringe pump driven by a linear actuator, and when the chamber is filled the reaction can begin. In this case, if the fluid contains glucose it will turn blue, which is detected by the microcontroller’s sensors. The color value is then displayed on a small screen mounted to the PCB, allowing the experimenter to take quick readings.

Chemistry labs like this aren’t limited to one specific reaction, though. The acrylic plates are straightforward to laser cut, so other forms can be made quickly. [Marb’s Lab] also made the syringe pump a standalone system, so it can be quickly moved or duplicated for use in other experiments as well. If you want to take your chemistry lab to the extreme, you can even build your own mass spectrometer.

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Most Powerful Laser Diodes, Now More Powerful

September 24, 2024 by Dan Maloney 31 Comments

Many hobbies seem to have a subset of participants who just can’t leave well enough alone. Think about hot rodders, who squeeze every bit of power out of engines they can, or PC overclockers, who often go to ridiculous ends to milk the maximum performance from a CPU. And so it goes in the world of lasers, where this avalanche driver module turns Nichia laser diodes into fire-breathing beasts.

OK, that last bit might be a little overstated, but there’s no denying the coolness of what laser jock [Les Wright] has accomplished here. In his endless quest for more optical power, [Les] happened upon a paper describing a simple driver circuit that can dump massive amounts of current into a laser diode to produce far more optical power than they’re designed for. [Les] ran with what few details the paper had and came up with a modified avalanche driver circuit, with a few niceties for easier testing, like accommodation for different avalanche transistors and a way to test laser diodes in addition to the Nichia. He also included an onboard current sensing network, making it easy to hook up a high-speed oscilloscope to monitor the performance of the driver.

For testing, [Les] used a high-voltage supply homebrewed from a Nixie inverter module along with a function generator to provide the pulses. The driver was able to push 80 amps into a Nichia NUBM47 diode for just a few nanoseconds, and when all the numbers were plugged in, the setup produced about 67 watts of optical power. Not one to let such power go to waste, [Les] followed up with some cool experiments in laser range finding and dye laser pumping, which you can check out in the video below. And check out our back catalog of [Les]’ many laser projects, from a sketchy tattoo-removal laser teardown to his acousto-optical filter experiments. Continue reading “Most Powerful Laser Diodes, Now More Powerful” →

Interesting Optical Journey Results In Hybrid Viewfinder For Smartphones

December 12, 2022 by Dan Maloney 5 Comments

Fair warning: if you ever thought there was nothing particularly interesting with optical viewfinders, prepare to have your misconception corrected by [volzo] with this deep-dive into camera-aiming aids that leads to an interesting hybrid smartphone viewfinder.

For most of us, the traditional optical viewfinder is very much a thing of the past, having been supplanted by digital cameras and LCD displays. But some people still want to frame a photograph the old-fashioned way, and the optical principles that make that possible are actually a lot more complicated than they seem. [volzo]’s blog post and video go into a great deal of detail on viewfinder optics, so feel free to fall down that rabbit hole — it’s worth the trip. But if you’d rather cut to the chase, the actual viewfinder build starts at about the 23:00 mark in the video.

The design is an interesting combination of lenses and beamsplitters that live in a 3D-printed enclosure. The whole thing slips over one end of a smartphone and combines an optical view of the scene that corresponds to the camera’s field of view with a small digital overlay from the phone’s screen. The overlay is quite simple: just some framing gridlines and a tilt indicator that’s generated by a little Android app. But it’s clear that much more information could be added now that [volzo] has all the optical issues sorted out.

We appreciate this deep dive into something that appears to be mundane and outdated, which actually proves to be non-obvious and pretty interesting. And if you have any doubt about the extreme cleverness of the camera engineers of yore, look no further than this sort-of solar-powered camera from the 1960s.

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Hackaday supercon badge PCB showing illuminated activity lights after being loaded with a punch card

Supercon Badge Reads A “Punch” Card

November 17, 2022 by Dave Rowntree 10 Comments

This year’s Hackaday Supercon, the first since 2019 thanks to the pandemic, was a very similar affair to those of the past. Almost every hardware-orientated hacker event has its own custom electronic badge, and Supercon was no different. This year’s badge is a simulation platform for a hypothetical 4-bit CPU created by our own [Voja Antonic], and presented a real challenge for some of the attendees who had never touched machine code during their formative years. The challenge set was to come up with the most interesting hack for the badge, so collaborators [Ben Hencke] and [Zach Fredin] set about nailing the ‘expandr’ category of the competition with their optical punched card reader bolt-on.

Peripheral connectivity is somewhat limited. The idea was to build a bolt-on board with its own local processing — using a PixelBlaze board [Ben] brought along — to handle all the scanning details. Then, once the program on the card was read, dump the whole thing over to the badge CPU via its serial interface. Without access to their usual facilities back home, [Ben] and [Zach] obviously had to improvise with whatever they had with them, and whatever could be scrounged off other badges or other hardware lying around.

One big issue was that most people don’t usually carry photodiodes with them, but luckily they remembered that an LED can be used as a photodiode when reverse-biased appropriately. Feeding the signal developed over a one Meg resistance, into a transconductance amplifier courtesy of a donated LM358 there was enough variation for the STM32 ADC to reliably detect the difference between unfilled and filled check-boxes on the filled-in program cards.

The CPU required 12-bit opcodes, which obviously implies 12 photodiodes and 12 LEDs to read each word. The PixelBlaze board does not have this many analog inputs. A simple trick was instead of having discrete inputs, all 12 photodiodes were wired in parallel and fed into a single input amplifier. To differentiate the different bits, the illumination LEDs instead were charlieplexed, thus delivering the individual bits as a sequence of values into the ADC, for subsequent de-serialising. The demonstration video shows that it works, with a program loaded from a card and kicked into operation manually. Such fun!

Punch cards usually have a hole through them and can be read mechanically, and are a great way to configure testers like this interesting vacuum valve tester we covered a short while back.

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Homebrew Optical Sensor Helps Your Diesel Pass The Smoke Test

June 27, 2022 by Dan Maloney 50 Comments

We’ve all heard of the smoke test, and we know that it’s the lowest possible bar for performance of an electronic device. If it doesn’t burst into flames when power is applied, you’re good to go for more functional testing. But the smoke test means something else for cars, especially those powered by diesel fuel. And passing diesel exhaust tests can become something of a chore.

To make passing these tests a little easier, [Janis Alnis] came up with this diesel exhaust monitor that measures the opacity of his car’s emissions. The sensor itself is quite simple, and mimics what commercial exhaust analyzers use: a LED and a photodiode at opposite ends of a tube of a specified length. Soot particles in exhaust passing through the tube will scatter light in a predictable way, and the numbers work out that a passing grade is anything greater than 53% transmission.

The sensor body is cobbled together from brass pipe fittings with glass windows epoxied into each end. Exhaust enters via a tee fitting attached to a hose and sampling tube, and exits through another tee. One window of the sensor has a cheap battery-powered flashlight as a light source, while the other end has a Texas Instruments OPT101 photodiode sensor. The sensor is connected to one of the analog inputs of an Arduino, which also runs a 128×64 pixel LCD display — inspired by this air quality meter — to show the current smokiness both graphically and as a percentage. The video below shows the sensor at work.

While there were some issues with soot buildup and water vapor condensation, using the sensor [Janis] discovered that a little bit of a warm-up drive got things hot enough to clear up his ride’s tendency to smoke a bit, allowing him to pass his inspection. Continue reading “Homebrew Optical Sensor Helps Your Diesel Pass The Smoke Test” →

Growing Silver Nanoprisms With Light

May 9, 2022 by Dave Rowntree 1 Comment

Nanoparticles sound a bit like science fiction to minds of your average hacker — too esoteric and out of reach to be something we might get to work with in our own lairs — but [Ben Krasnow] of [Applied Science] over on YouTube has proven that they most definitely can be made by mere mortals, and importantly they can be tuned. With light. That’s right, nano particle growth appears to be affected very strongly by being illuminated with specific wavelengths, which locks-in their size, and thus defines their light-bending properties. This is the concept of photo mediated synthesis, which causes nanoparticles to clump together into different configurations depending on the wavelength. The idea is to start with a stock solution of Silver Nitrate, which is then reduced to form silver nanospheres which are then converted to larger silver nanoprisms, sized according to the wavelength of the illuminating source.

The process seems simple enough, with a solution of Silver Nitrate and Sodium Citrate being vacuum degassed to remove oxygen, and then purged by bubbling argon or nitrogen. Sodium Borohydride acts as a reducing agent, producing silver metal nanoparticles from the Silver Nitrate solution. The Sodium Citrate coats the silver nanoparticles, as they are produced, preventing them clumping together into a mushy precipitate. PVP (Polyvinylpyrrolidone) is added, acting as a colloiding agent preventing the coated nanoparticles from clumping together, and helping keep the solution stable long enough for the photo mediated synthesis process to complete. Finally, the pH is adjusted up to 11 using sodium hydroxide. The resulting silver nanoparticle stock solution has a pale yellow colour, and is ready for the final particle size selection using the light source.

The light source was custom made because [Ben] says he couldn’t find something suitable off the shelf. This is a simple design using a Teensy to drive an array of PAM2804 LED drivers, with each one of those driving its own medium power LED, one for each of the different wavelengths of interest. As [Ben] stresses, the naïve approach of trying to approximate a specific colour with an RGB LED setup would not work, as although the human eye perceives the colour, the actual wavelength peak will be totally wrong, and the reaction will not proceed as intended. The hardware design is available on MultiSpectLED GitHub for your viewing pleasure.

Nanoparticles have all kinds of weird and wonderful properties, such as making the unweldable, weldable, enabling aluminium to be 3D printed, and even enabling the production of one of our favourite liquid toys, ferrofluid.

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Paper Tape Reader Self-calibrates, Speaks USB

April 16, 2022 by Donald Papp 22 Comments

Input devices consisting of optical readers for punched paper tape have been around since the earliest days of computing, so why stop now? [Jürgen]’s Paper Tape Reader project connects to any modern computer over USB, acting like a serial communications device. Thanks to the device’s automatic calibration, it works with a variety of paper materials. As for reading speed, it’s pretty much only limited to how fast one can pull tape through without damaging it.

Stacked 1.6 mm PCBs act as an enclosure, of sorts.

While [Jürgen]’s device uses LEDs and phototransistors to detect the presence or absence of punched holes, it doesn’t rely on hardware calibration. Instead, the device takes analog readings of each phototransistor, and uses software-adjusted thresholds to differentiate ones from zeros. This allows it to easily deal with a wide variety of tape types and colors, even working with translucent materials. Reading 500 characters per second isn’t a problem if the device has had a chance to calibrate.

Interested in making your own? The build section of the project has all the design files; it uses only through-hole components, and since the device is constructed from a stack of 1.6 mm thick PCBs, there’s no separate enclosure needed.

Paper tape and readers have a certain charm to them. Cyphercon 4.0 badges featured tape readers, and we’ve even seen the unusual approach of encoding an I²C byte stream directly onto tape.