Penny and Paper Clip Heat Sinks

A bunch of audio heads over at the Head-Fi forum were discussing handy and quick heat sinking methods, leading to much speculation and conjecture. This finally prompted [tangentsoft] to take matters in his own hands and run some tests on DIY Heat Sinks.

The question that sparked this debate was if a paper clip is a good enough heat sink to be used for a TO220 package. Some folks suggested copper pennies (old ones minted 1981 and earlier – the new ones are zinc with copper plating and won’t help much). [tangentsoft] built a jig to test six LM317 regulators in constant current mode set to 0.125A and 2w dissipation. The six configurations were a paper clip, a single penny bolted to the regulator, a regular Aavid TO220 heat sink, a set of 4 pennies bolted, a single penny epoxy glued and finally a single penny soldered directly to the regulator.

The results were pretty interesting. The paper clip scored better than any of the single pennies! The quad-penny and the Aavid heat sink fared above all the other configurations, and almost at par with each other. [tangentsoft] posts his review of each configurations performance and also provides details of his test method, in case someone else wants to replicate his tests to corroborate the results. He tested each configuration independently for one hour, gathering just over 10000 readings for each setup. Other nearby heat sources were turned off, and he placed strategic barriers around the test circuit to isolate it from the effects of other cooling / heating sources. He even removed himself from the test area and monitored his data logging remotely from another room. When he noticed a couple of suspect deviations, he restarted the test.

[tangentsoft] put all the data through Mathematica and plotted his results for analysis, available at this link [pdf, 2.8MB]. So the next time you want to heat sink a regulator for cheap, just hunt for Clippy in your box of office supplies. Do remember that these methods will work for only a couple of watts dissipation. If you would like to cast and build your own heat sinks out of aluminum, check out this post about DIY Aluminum heat sink casting. And if you need help calculating heat sink parameters, jump to 12:00 minutes in this video from [Dave]’s EEVBlog episode on Dummy loads and heat sinks.

Thanks to [Greg] for sending in this tip.

New Part Day: Time Of Flight Sensors

Every robotics project out there, it seems, needs a way to detect if it’s smashing into a wall repeatedly, acting like the brainless automaton it actually is. The Roomba has wall sensors, just about every robot kit has some way of detecting obstacles its running into, and for ‘wall-following robots’, detecting objects is all they do.

While the earliest of these robots used a piece of wire and a metal contact to act like a switch for these object detectors, ultrasonic sensors – the kind you can buy on eBay for a few bucks – have replaced this clever wire spring switch. Now there’s a new sensor for the same job – the VL6180 – and it measures the speed of light.

The sensors that are used for object and collision detection now use either ultrasonic or infrared light. They’re susceptible to noise, and if you’re doing anything automated, you really don’t want rogue measurements. A time of flight sensor clocks out photons and records how long it takes them to return at 299,792,458 meters per second. It’s less sensitive to noise, and if you can believe this SparkFun demo of this sensor, extremely accurate

This is not the first Time of Flight distance sensor on the market; earlier this week we saw a project use a sensor called the TeraRanger One. This sensor costs €150.00. The VL6180 sensor costs about $6 in quantity one from the usual suspects, and breakout boards with the proper level converters and regulators can be found for about $25. More expensive sensors have a greater range, naturally; the VL6180 is limited to somewhere between 10cm (on paper) and 25cm (in practice). But this is cheap, and it measures the time of flight of pulses of light. That’s just cool.

Digitally Controlled Pot Taper

Those twisty knobs connected to potentiometers aren’t necessarily a strict linear progression from one resistance to another. Potentiometers have a taper. Yes, sometimes it’s a linear taper that’s a straight line from one resistance to another, but you can find log (audio) taper pots, and anti-log taper pots. It’s been this way for a hundred years, and now we have a pot with a digitally controllable taper thanks to a guitar pedal that fits in your shoe.

For the last few years, [John] has been hard at work creating the SoulPedal, a shoe insert that’s the wireless, wearable alternative to expression pedals, wah pedals, and every other guitar effects pedal that uses an ankle. [John] got the idea by replacing the light-sensitive resistor in a wah pedal with a force sensitive resistor in his shoe. It worked, but there were wires. Now the SoulPedal is based on a TI SoC +Radio with all the niceties you would expect.

When designing the ‘base station pedal’, [John] realized he had a digital pot with two channels, and the entire device only uses one of these channels. Instead of letting that little bit of silicon go to waste, [John] wired these two digital pots in parallel, allowing the user to customize the taper of a digital pot. If you’re asking yourself, ‘why’, the answer is, ‘because he could.’

It’s an interesting application for sure, and while this digitally controllable pot can replicate the linear, log, and anti-log tapers, the really interesting thing will be to see what non-standard tapers sound and feel like.

Towards A Tiny Pick And Place Head

One of the projects that has been on [Peter Jansen]’s build list for a long time – besides a fully functioning tricorder, of course – is a pick and place machine. It’s a project born out of necessity; each tricorder takes four days to assemble, and assembling the motherboard takes eight hours with a soldering iron and hot air gun. The pick and place machine isn’t complete yet, but one vital component – the vacuum head for picking up components – is getting there with the help of some odd components.

A few months ago, [Peter] saw a post on Hackaday about repurposing a tiny piezo micro blower for use as an extremely small vacuum pen. The original build was extremely simple – just a few pieces of foam board and a power supply, but the potential was there. A tiny electric air pump that’s able to pick up large chips and modules along with tiny resistors without having to run a hose through the mechanics of a CNC gantry is a godsend.

[Peter] got his hands on one of these micro blowers and started work on a proper tool head for a pick and place machine. A port on the micro blower was covered so it would suck instead of blow, the vacuum port was threaded through a stepper motor with a hollow shaft, and a fine tip was attached to the end.

What can this vacuum head pick up? 0604 size resistors aren’t a problem, but larger modules are simply too heavy. It looks like this micro blower would only be able to pick up small components. There are other options, though: [Grant Trebbin] has had some luck with a larger pump from Sparkfun, but this requires a vacuum line to run through a CNC gantry. There’s still some work to do before a small vacuum head shows up on the tool head of a pick and place machine, but given how long it takes [Peter] to put together a single tricorder, it’s well worth investing the time to do this right.

New Part Day: Three-dimensional USB Connectors

There’s an old joke that says USB cables do not exist in three-dimensional Euclidian space. Try to plug a USB cable in a socket, and the first try will always be wrong. Flip it, try to plug it in, and that will also be wrong. You will only succeed on the third try, and this is proof that USB connectors exist in higher planes of reality with arcane geometries. The joke is as old as the Pythagoreans, who venerated USB connectors as gods.

The waveform has collapsed, the gods profaned, and USB connectors that exist in only three dimensions have arrived. We’re talking, of course, about reversible USB Type A connector that will plug in the first time, every time. No need for electromancy or the “looking on the cable for the USB logo and plugging it in with that side up” method used by tech plebeians.

This discovery came after going through my daily roundup of crowdfunding press releases, eventually landing me on this idiotic project. It’s a USB charge cable that’s supposed to charge your phone twice as fast, despite the fact that charging speed is a function of current, and that’s determined by whatever you’re charging from, not the cable. Terrible idea, but they do have something interesting: a three-dimensional USB connector.

connUSBThe connector isn’t the brand new USB 3.1 Type C connector that will eventually find its way into phones, laptops, wearables of all types. This is your standard Type A USB plug you’ve known and loved for the past eighteen years. The difference here is that the chunky block of plastic that has made the common USB cable non-reversible for so many years is gone. In its place is a tiny strip of plastic that has contacts on both sides. Yes, it took nearly two decades for someone to figure out this would be a marketable idea.

While searching for a source for these three-dimensional USB connectors, the only source I could come up with was Wurth Elektronik, With Farnell/Element14 carrying a selection of connectors, a few available on Digikey, and some available on Mouser. There are even a few pre-made reversible cables available, with Tripp Lite leading the game right now.

For integrating one of these connectors into your build, there’s only one thing to watch out for: the pinout for these plugs is mirrored on each side of the thin strip of plastic going down the middle of the connector. This means your VCC and GND pins will be right next to each other, your D+ and D- signal pins right next to each other, and now you have to do your layout with eight pins instead of only four.

While it may not be groundbreaking and it makes for some confusing PCB layout work, but as told by a highly successful crowdfunding campaign, this can be a real feature for a product.

If you’ve recently come across a component, connector, or part that’s unique, interesting, or downright cool everyone should know about, send it on in and we’ll take a look at it.

Wood-Only Kart Race Inspires Fancy Wooden Bearings

The mountainous Italian town of Artena holds an annual soap box derby for wood vehicles – and they mean 100% wood, not a speck of anything else. Fierce competition led [Alessio] to engineering and CNC fabricating these gorgeous wooden roller bearings for the wheels to give him an edge.

Thousands in costume attend the renaissance faire known as “Palio delle contrade di Artena”, and the popular wood-only race is called “La Carettella.” The karts are operated by a two-man team: one in front who brakes, the other in the rear who hops on and off to push as needed throughout the course. There appears to be no steering from the wheels** so turning is also a two-man effort. The wooden levers dragging on the pavement provide some steering from the “driver”, and the push-man often manhandles the entire rear end, drifting where necessary.
HAD - Carettella2The course also includes full-width obstacles like hay bales. Teams are divided by community or “contrada”, and it was [Alessio]’s team captain who came to him with the special request of roller bearings. Unable to find evidence of other wooden bearings, [Alessio] knew he would have to invent them himself – so he did.

Continue reading “Wood-Only Kart Race Inspires Fancy Wooden Bearings”

Flashing the ESP8266 In Windows

It’s only been a few months since the ESP8266 rolled out of some factory in China, and already the community is moving from simply getting custom firmware to work on the device to making the development tools easy to use. That’s huge – the barrier to entry is lowered, getting even more people on board with this very cool Internet of Things thing.

While the majority of the community is settling on using the Lua interpreter firmware, there’s still the matter of getting this firmware uploaded to the ESP. [Peter Jennings] of Microchess fame has been working on a Windows app to upload firmware to the ESP via a serial interface. There’s not much to it, but this will allow you to upload the community-created Lua firmware, set the WiFi credentials, toggle GPIO pins, and give you the ability to write a little bit of Lua in the same window.

If you’re looking for something that isn’t designed exclusively for Windows, there’s an alternative firmware flasher over on the nodemcu Github. This flasher also connects the ESP8266 to a network and uploads firmware. It’s a stripped-down programmer without a serial terminal or the ability to toggle pins, but there are plans for making this programmer cross-platform.