Tag Archives: hardware

Design & Build Part 2: Multi-Band, Phasing SSB, and SDR

via Hackaday » hardware

 

Amateur radio is the ultimate hacker’s hobby. You can design, build, and put on the air your own high power transceivers. And with this homemade gear you are able to reach out directly, not relying on any infrastructure whatsoever, to connect with people all over the world. It is a thrilling experience to communicate with that long distance station using equipment you created, where you know at that instant what every single transistor is doing as you key down the mic.

In a previous post I described how SSB radio equipment worked and provided an example of a single-band 20m SSB transceiver. In this post I will discuss a multi-band SSB transceiver, an entire homemade amateur station including amplifiers, and conclude with software defined radio (SDR) that you can make in one weekend.

10m and 6m Dual-Band SSB

My second SSB transceiver was dual-band spanning both 6m and 10m wavelengths. I built this radio as part of the ARRL ‘home brew challenge 3′. This followed the same block diagrams as those shown in the previous post except that the two frequency bands of interest spanned one whole octave at 28 MHz and 54 MHz, resulting in additional switching and a wider bandwidth VFO.

Similar fabrication techniques were used, resulting in an old-school appearance.

best image Photos of the dual-band 6m and 10m SSB/CW transceiver. HPIM3019 DSC_0201 Block diagram of the 10m and 6m dual-band SSB/CW transceiver.

Schematics and details are found in the full article in March 2013 QST, and design notes here. The interesting thing about this radio is that its VFO, power amplifier, and front-end cover all HF bands up to the VHF band 2m. This radio could quite easily be made into an all-band radio if the filters were built-out.

An Entire Station!

The most impressive home built station I’ve ever seen was by Mark Mandelkern, K5AM.  Mark published details of all this gear in QEX magazine back in the late 1990s and early 2000s, with schematics, block diagrams, and more are available here.

rack Mark Mandelkern, K5AM, built his entire amateur radio station from scratch. More photos of Mark Mandelkern's station.

In Mark’s Own Words

“All the gear was newly designed and built from scratch. But I was not about to reinvent the superheterodyne. Each project begins with a thorough study of the handbooks and relevant magazine articles. I glean ideas from all previous builders, to whom many thanks are due. Design means selecting and choosing the best ideas which will help produce the intended results. Individual circuits are described in the handbooks; the real design work is to combine them into a complete functioning unit. Getting a whole station built in a finite interval of time meant using mostly tried-and-true methods, and setting to work without trying to invent a new circuit for each stage.”

There’s More

Others who have made their own multi and single-band SSB transceivers:

And others suggest searching on YouTube for on-air demos of some of these radios or post in the comments section.

Phasing SSB and Software Defined Radio

There are other methods to implement SSB equipment, including direct-conversion using phasing (either digital or analog). In this architecture, an I/Q image rejection mixer is used to mix up (for transmit) or down (for receive) to directly modulate or demodulate SSB signals. The back end after the IQ mixer can be implemented with either op-amps or digitization. This is one of the common architectures for early SSB transmitters and today this is the preferred architecture for entry-level software defined radio (SDR) receivers and transmitters.

Photos of a vintage phasing SSB amateur radio equipment. Slicer-recap_zps532b3fdb slb

Software Defined Radio (SDR)

SDR might be a great option for those of you who are more interested in building a kit or writing code instead of building a scratch-built design.  In many cases the software is already written.  And let’s face it, SDR is the future of radio by pushing what was previously analog circuitry into the digital domain, which trades CPU cycles for reductions in analog circuit complexity.

The Soft Rock SDR transceiver kit.
The Soft Rock SDR transceiver kit.

There are many SDR kits available today, including those by AE9RB, the Picastar, or the Heremes.  You can also buy the commercialized version or can mix and match the exciter, PA, and filter boards.  Recently, an SDR was developed using a teensy. Check out hackrf or hackrfblue for the professional to convert to amateur use with the addition of a good power amplifier and some filters.

The best performing software-defined (or DSP) receivers use a hybrid architecture mixing the best practices of analog design with an SDR back-end (sometimes known as a ‘roofing filter‘).  This provides the high-dynamic range architecture of an analog radio with the flexibility of a software defined radio.  This is why the Elecraft K3 is a top performing radio (it is also available as a kit).

Build It

The only way to get started is to build something. Start small, check out the QRP community, try making a single-conversion receiver, try an entry-level SDR, and finally move up to something with a crystal IF filter. Borrow and scale circuits from books such as these:

Or leverage complete ICs and modules like those from Mini-Circuits. There is nothing like making that first long distance contact on radio gear you created from scratch.


Acknowledgement

My cousin, Juliet Hurley, MBA, MSF, MAC for type editing this post.

Author Bio
Gregory L. Charvat only operates radio equipment he builds from scratch, is the author of Small and Short-Range Radar Systems, co-founder of Hyperfine Research Inc., Butterfly Network Inc. (both of which are 4catalyzer companies), visiting research scientist at Camera Culture Group Massachusetts Institute of Technology Media Lab, editor of the Gregory L. Charvat Series on Practical Approaches to Electrical Engineering, and guest commentator on CNN, CBS, Sky News, and others. He was a technical staff member at MIT Lincoln Laboratory where his work on through-wall radar won best paper at the 2010 MSS Tri-Services Radar Symposium and is an MIT Office of the Provost 2011 research highlight. He has taught short radar courses at MIT where his Build a Small Radar course was the top-ranked MIT professional education course in 2011 and has become widely adopted by other universities, laboratories, and private organizations. Starting at an Early Age, Greg developed numerous radar systems, rail SAR imaging sensors, phased-array radar systems; holds several patents; and has developed many other sensors and radio and audio equipment. He has authored numerous publications and has received press for his work. Greg earned a Ph.D in electrical engineering in 2007, an MSEE in 2003, and a BSEE in 2002 from Michigan State University, and is a senior member of the IEEE where he serves on the steering committee for the 2010, 2013, and 2016 IEEE International Symposium on Phased Array Systems and Technology and chaired the IEEE AP-S Boston Chapter from 2010-2011.


Filed under: hardware, how-to, news, radio hacks

Using The Red Pitaya As An SDR

via Hackaday » hardware

The Red Pitaya is a credit-card sized board that runs Linux, has Ethernet, and a good bit of RAM. This sounds a lot like a Raspberry Pi and BeagleBone Black, but the similarities end there. The Red Pitaya also has two RF inputs, two RF outputs, and a load of digital IOs, all connected to an Xilinx SoC that includes an FPGA. [Pavel] realized the Pitaya had all the components of a software-defined radio, and built an implementation to prove it.

The input for the SDR taps directly into one of the high impedance inputs with a simple loop antenna made out of telephone cable. The actual software-defined part of this radio borrows heavily from an Xilinx application note, while everything is controlled by either SDR# or HDSDR.

[Pavel] included a pre-built SD card image with all his software, so cloning this project is simply a matter of copying an SD card and building an antenna. The full source is also available, interesting if you would like to muck about with FPGAs and SDRs.


Filed under: FPGA, hardware, radio hacks

The Wisest Wizard Doesn’t Drink from Cans

via Hackaday » hardware

“Wizard Staff” or “Wisest Wizard” is a drinking game played at parties where the attendees participate by taping the empty cans of the drinks they’ve consumed on top of one another to form a staff of inebriated power. A person with a longer staff is considered to be at a higher level and can therefore command lesser wizards to pound their current beverage to a point they see fit. Not everyone at a party necessarily drinks their tasty libation of choice from a can however. So, [Ahmed] and his group came up with a solution for those of us who might alternately prefer to wield a pint glass of power instead.

In their hardware project for Hack Illinois 2015, [Brady Salz], [Ahmed Suhyl], [Dario Aranguiz], [Kashev Dalmiaand] decided to add a zest of tech to the game. For their updated rendition, glasses are equipped with battery packs for mobility, a Spark micro-controller, and different colored LEDs as indicators. A couple of wires reach into the bottom of each glass to measure conductivity and keep track of the number of times it is filled and then emptied. In leu of towers of aluminum husks and duct-tape, the group developed a simple Android app for participants to log into which will track and visualize the standings of each player registered to one of the glasses. They even created a pebble version of the app that will display all the same information in case you don’t want to risk handling your phone while drinking… heh.

For an added level of fun, once a player reaches a certain level above someone else, they unlock the option to “challenge” the lesser adversary. By selecting that person’s user name in the app, the LED and buzzer on their glass will spring to life, letting them know they’ve been chosen to chug the rest of their drink. If you’re curious how they made it work, you can check out the team’s code on Github and maybe take a stab at giving the game a makeover of your own.


Filed under: Android Hacks, hardware

Low-Voltage Tesla Coil Uses a Relay Instead of a Spark Gap

via Hackaday » hardware

[Teodor] writes in with a unique Tesla coil he designed and built. Unlike most Tesla coils, [Teodor]’s design is able to run with a fairly low input voltage because it doesn’t use a static spark gap like most Tesla coils. Instead, his coil uses a relay in place of a spark gap.

[Teodor] built his coil using leftover components from his old school, making good use of some parts that might have otherwise been thrown away. The most critical component of his circuit, the relay, is just a standard normally-closed relay that is rated at 20A. [Teodor] wired the relay so that it energizes its own coil whenever it is shut. This causes the relay to briefly open every time the coil is energized, creating a resonant circuit. The resonant circuit charges a tank capacitor and places it in series with the primary coil inductor every time the relay closes, forming the tank circuit of his design.

With [Teodor]’s design, the resonant frequency of the secondary is nearly identical to that of the primary. This creates a significant voltage boost, helping produce very high voltages from such a low input voltage. The only downside to this design that [Teodor] recently discovered is that the relay contacts get red-hot after a few minutes of operation. Not optimal, but it still works! Check out [Teodor]’s writeup for more details and instructions on how to build your own.


Filed under: hardware, how-to

Reverse Engineering Wireless Temperature Probes

via Hackaday » hardware

[bhunting] lives right up against the Rockies, and for a while he’s wanted to measure the temperature variations against the inside of his hour against the temperature swings outside. The sensible way to do this would be to put a few wireless temperature-logging probes around the house, and log all that data with a computer. A temperature sensor, microcontroller, wireless module, battery, case, and miscellaneous parts meant each node in the sensor grid would cost about $10. The other day, [bhunting] came across the exact same thing in the clearance bin of Walmart – $10 for a wireless temperature sensor, and the only thing he would have to do is reverse engineer the protocol.

These wireless temperature sensors are exactly what you would expect for a cheap piece of Chinese electronics found in the clearance bin at Walmart. There’s a small radio operating at 433MHz, a temperature sensor, and a microcontroller under a blob of epoxy. The microcontroller and transmitter board in the temperature sensor were only attached by a ribbon cable, and each of the lines were labeled. After finding power and ground, [bhunting] took a scope to the wires that provided the data to the radio and took a look at it with a logic analyzer.

After a bit of work, [bhunting] was able to figure out how the temperature sensor sent data back to the base station, and with a bit of surgery to one of these base stations, he had a way to read the temperature data with an Arduino. From there, it’s just a data logging problem that’s easily solved with Excel, and [bhunting] has exactly what he originally wanted, thanks to a find in the Walmart clearance bin.


Filed under: hardware, home hacks

Custom Case Made Entirely Out of PCBs

via Hackaday » hardware

So you’ve finished your project. You’ve got a wonderful circuit, a beautiful PCB, and everything works perfectly. You’re done right? Well, maybe not. Sure, a bare PCB might be fine for a dev board, but what if you have a LCD to mount, a knob that needs turning, and buttons that need pressing. Yeah, that potentiometer hanging off the board by a few wires isn’t so pretty, is it? So it’s time for a case. Yuck. We all hate modifying cases.

[Electrodacus] came up with a clever solution in the form of stacking PCBs to form a case. In his project, he actually has the circuitry spread across 3 PCBs, and uses surface mount connectors to connect them in a stack. Along the edges are specifically shaped PCBs to complete the enclosure. This technique could be used with only one PCB containing all the circuitry, and the others acting as the case sides and top.

In this solar battery management project, the base layer has most of the power circuitry. This layer uses an aluminum metal core PCB for heat dissipation. The center layer is home for the micro controller and supporting components. And the top layer is the “front panel” with capacitive touch buttons and a cut out for a LCD. The top layer silk screen contains the logo, button markings, and the pin out of all the connectors.

If you hate drilling and filling cases (as much as we do), this technique might be right for your next project.

[via EEVBlog Forums]


Filed under: hardware

OK Google, Open Sesame

via Hackaday » hardware

There are a myriad of modern ways to lock and unlock doors. Keypads, Fingerprint scanners, smart card readers, to name just a few. Quite often, adding any of these methods to an old door may require replacing the existing locking mechanism. Donning his Bollé sunglasses allowed [Dheera] to come up with a slightly novel idea to unlock doors without having to change his door latch. Using simple, off the shelf hardware, a Smartwatch, some code crunching and a Google Now app, he was able to yell “OK Google, Open Sesame” at his Android Wear smartwatch to get his apartment  door to open up.

The hardware, in his own words, is trivial. An Arduino, an HC-05 bluetooth module and a servo. The servo is attached to his door latch using simple hardware that looks sourced from the closest hardware store. The code is split in to two parts. The HC-05 listens for a trigger signal, and informs the Arduino over serial. The Arduino in turn activates the servo to open the door. The other part is the Google Now app. Do note that the code, as he clearly points out, is “barebones”. If you really want to implement this technique, it would be wise to add in authentication to prevent all and sundry from opening up your apartment door and stealing your precious funky Sunglasses. Watch a video of how he put it all together after the break. And if you’re interested, here are a few other door lock hacks we’ve featured in the past.


Filed under: Android Hacks, hardware

Nordic NRF24L01+ – Real vs Fake

via Hackaday » hardware

[zeptobars], the folks behind all the decapping hard work and amazing die shots are at it again. This time they decided to look under the hood of two identical looking Nordic nRF24L01+ chips.

The nRF24L01+ is a highly integrated, ultra low power (ULP) 2Mbps RF transceiver IC for the 2.4GHz ISM (Industrial, Scientific and Medical) band. Popular, widely used and expensive – and the counterfeit foundries are drawn to it like honey bees to nectar. But to replicate and make it cheaper than the original, one needs to cut several corners. In this case, the fakes use 350nm technology, compared to 250nm in the original and have a larger die size too.

These differences mean the fakes likely have higher power usage and lower sensitivities, even though they are functionally identical. The foundry could have marked these devices as Si24R1, which is compatible with the nRF24L01 and no one would have been wiser. But the lure of higher profits was obviously too tempting. A look through Hackaday archives will dig up several posts about the work done by [zeptobars] in identifying fake semiconductors.


Filed under: hardware

Castellated Breakout is Pitchin’ Brilliant!

via Hackaday » hardware

Radio, WiFi and similar modules are getting smaller by the day. Trouble is, they end up having non-DIY-friendly, odd pitch, mounting pads. Sometimes, though, simple hacks come around to help save the day.

[Hemal] over at Black Electronics came up with a hack to convert odd-pitch modules to standard 2.54mm / 0.1″. The process looks simple once you see the detailed pictures on his blog. He’s using the technique to add 2mm pitch modules like the ESP8266 and XBee by soldering them to standard perf board. Once they are hooked to the board, just add a row of male header pins, trim the perf board and you’re done. Couldn’t get simpler.

Another technique that we’ve seen is to solder straight across the legs and cut the wire afterward. That technique is also for protoyping board, but custom-sized breakout boards are one good reason to still keep those etchants hanging around. If you have other techniques or hacks for doing this, let us know in the comments.


Filed under: hardware, how-to, repair hacks

Hack allows ESP-01 to go to Deep Sleep

via Hackaday » hardware

The ESP-01 module based on the ESP8266 is all the rage with IoT folks at the moment – and why not. For about 5 bucks, it can’t be beat on price for the features it offers. The one thing that such radios do a lot is suck power. So, it’s no surprise that ways to cut down on the juice that this device consumes is top priority for many people. [Tim] figured out a simple hardware hack to get the ESP-01 to go to deep sleep, effectively reducing its current draw to 78uA – low enough to allow battery powered deployment.

While [Tim] was working on understanding the ESP8266 tool chain (NodeMCU firmware > Lua interpreter > ESPlorer IDE), he realized that some essential pins weren’t accessible on the ESP-01 module. [Tim] built a Dev board on perf board that let him access these pins and also added some frills while at it. We’re guessing he (or someone else) will come up with a proper PCB to make things easier. But the real hack is on the ESP-01 module itself. [Tim] needed to hardwire the ‘post-sleep-reset-pin’ on the MCU to the Reset terminal. That, and also pry off the indicator LED’s with a screw driver! That sounds a bit drastic, and we’d recommend pulling out your soldering iron instead. If you’re one of the unlucky one’s to receive the “magic smoke” releasing ESP8266 modules, then you don’t need the LED anyway.


Filed under: hardware, how-to, news, wireless hacks

Hacking the Nike+ Fuelband

via Hackaday » hardware

[Simone] was trying to reverse-engineer the Bluetooth protocol of his Nike+ Fuelband and made some surprising discoveries. [Simone] found that the authentication system of the Fuelband can be easily bypassed and discovered that some low-level functions (such as arbitrarily reading and writing to memory) are completely exposed to the end user or anyone else who hacks past the authentication process.

[Simone] started with the official Nike app for the Fuelband. He converted the APK to a JAR and then used JD-Gui to read the Java source code of the app. After reading through the source, he discovered that the authentication method was completely ineffective. The authenticator requires the connecting device to know both a pin code and a nonce, but in reality the authentication algorithm just checks for a hard-coded token of 0xff 0xff 0xff 0xff 0xff 0xff rendering the whole authentication process ineffective.

After he authenticated with the Fuelband, [Simone] started trying various commands to see what he could control over the Bluetooth interface. He discovered that he could send the device into bootloader mode, configure the RTC, and even read/write the first 65k of memory over the Bluetooth interface–not something you typically want to expose, especially with a broken authentication mechanism. If you want to try the exploit yourself, [Simone] wrote an Android app which he posted up on GitHub.


Filed under: hardware, wearable hacks

Save Data from Old Scopes with a GPIB Disk Emulator

via Hackaday » hardware

If you still use old test equipment on a regular basis, you probably have been frustrated by the lack of options for pulling data off these aging devices. Many higher-end devices are equipped with GPIB ports, which are general purpose buses for communicating with a variety of obsolete peripherals. Since GPIB disk drives aren’t too common (or practical) these days, [Anders] made a GPIB adapter that emulates a disk drive and stores data to an SD card.

[Anders] designed a PCB with a PIC microcontroller that plugs into a GPIB port. The PIC emulates a disk drive using the AMIGO protocol or the SS/80 protocol, which can be selected in a configuration file on the SD card. Most test equipment supports one of these two protocols, so his adapter should work with pretty much any GPIB-equipped kit.

Data is saved to a single image file on the SD card, which is encoded in a native HP disk format. The image file can be opened on Windows and Linux with some utilities that [Anders] mentioned on his project page. If you have any old test equipment withGPIB lying around and want to build your own, the schematic and source code are up on his site or [Anders] is selling bare boards.

Now if it’s a protocol converter that you need we’ve seen those in a couple of different varieties.


Filed under: hardware, tool hacks

A Wireless Web-Connected Morse Code Keyer

via Hackaday » hardware

[Kevin] recently scored a Morse code keyer/sounder unit from the 1920s on eBay. While many hams would love to use an old keyer for CW, [Kevin] took a different route and repurposed it into a wireless web-connected morse code keyer.

[Kevin] mounted an Arduino Yun under the keyer, which listens for user input and provides web connectivity. The Yun connects to [Kevin]’s open-source web API he calls “morsel,” which allows it to send and receive messages with other morsel users. When a message is keyed in, the Yun publishes it to the API. When another keyer queries the API for incoming messages, the Yun downloads the morse sequence and replays it on the sounder.

[Kevin] also added some copper electrodes to the top of his enclosure, which act as capacitive buttons while keeping the keyer’s old-school appearance. The left button replays the most recently received message, and the right button sets the playback speed. Check out the video after the break to hear and see the keyer in action.

Thanks for the tip,  [Jarrod].


Filed under: hardware

A “cool” project based in the most southern location ever!

via Arduino Blog

11829959703_239ed40364_z

At the end of last year we received an email on our support center from an unusual location. It was sent by Giovanni Bianchini an italian physicist researching at Concordia Station, located in East Antarctica (see the red dot in the map below!) where the hottest temperature is around -25C?/-13F. He was working on a project based on Arduino and yes, this is the Arduino project based in the most southern location ever! When we realized that we thought of getting in touch with him and discover the details.

Giovanni was very happy to start a conversation with us, shared  some pictures and explained  why and how he is using Arduino in Antartica.

 Tell us a bit more about Concordia Station and what you are doing there…

 Concordia Station is a scientific research base placed more or less in the middle of the plateau region, East Antarctica. This site is peculiar for the fact of being surrounded of at least 1000 km of ice plain in every direction, a condition that provides relatively stable and unperturbed weather conditions and a dry and very transparent atmosphere, that is the reason for which it has been chosen for astronomic and atmospheric observations.

The downside is isolation: the nearest emplacement is the russian Vostok base, at a mere 700 km, while the italian and french bases on the coast, that are the intermediate stops for the researcher coming to Concordia, are both at more than 1000 km. Usually coming to Concordia involves a 7-8 hours flight from Christchurch (NZ) to the italian “Mario Zucchelli” or the US “Mc Murdo” bases and a second 5 hours flight to Concordia. In alternative it’s possible to reach the french Dumont D’Urville base from Hobarth (AU) with a 7 days (more or less, much more than less…) cruise on the “L’Astrolabe” ship, and fly to Concordia. Since every stop in a base usually involves one or more days of stop, depending on the weather conditions, reaching Concordia is somewhat an adventure itself…

ConcordiaStationMap

What is your job at the station?

Most of the instrumentation operating in Concordia is installed in some “shelters” placed some hundreds of meters upwind from the base, in order to sample unperturbed air. The shelters are put on elevated platforms to prevent snow accumulation, and are heated and connected to the base LAN, so the instrumentation can be remotely operated.

Specifically I work on atmospheric physics, and in the past two year I am responsible of a scientific project (Concordia Multi-Process Atmospheric Studies) that involve several instruments performing vertical remote sensing of atmospheric properties. The setup include two LIDARs, one SODAR, and an infrared spectroradiometer (Radiation Explorer in the Far-Infrared – REFIR).

All this instrumentation is installed in the Physics shelter, and operates continuously, even during the winter period, in which the base is completely isolated for almost 9 months and is crewed by only 12 persons. This implies that the instruments operating during winter should require the least attendance possible from the reduced crew, and possibly should be remotely accessed from Italy for checking and maintenance.

10821772925_4fe3a61d03_z

How are you using Arduino at the base?

While the shelters are quite a comfortable workplace for researchers and technicians, they present a critical (and maybe unexpected) problem for the instrumentation: overheating. The small volume, good thermal insulation, high density of powered devices, united with the low heat transfer capacity of the very dry air inside, makes heat dissipation a difficult task.

 For this reason, the first application I found for an Arduino board in Antarctica has been a cooling system for the REFIR spectroradiometer.

This optical instrument features tens of optical components with critical alignment requirements, so in the past years every time the instrument was subject to a strong thermal cycle, it needed to be realigned.

The original design provided just a simple heater with an analog proportional control loop (go figure you had to heat things at the south pole). Luckily, providing cooling power was as simple as getting air from outside and sending it to the instrument box through a tube. A valve and a fan regulate the cool air flow according to the instrument temperature.

The old heaters, the flow valve (servo controlled) and the cooling fan all are controlled by an Arduino Uno board, with a simple proportional loop that allows a thermal stability of a few tenths of degree.

Using an Ethernet Shield, all the system parameters (temperature, setpoint, cooling and heating gain, valve position) can be monitored through a simple web interface that gives this kind of output:

REFIR-PAD
thermal control
(commands: T, R, H, F, G, V, M, Z)
setpoint = 20.00
averages = 128
threshold = 0.10
fan_gain = 300
htr_gain = 200
valve_full = 0
valve_mid = 0
valve_zero = 38
temperature = 20.49
fan_drv = 118
htr_drv = 0
val_pos = 0

Parameters can also be set sending commands to the web server on the arduino board, for example, the command:

http://192.168.14.3:81/&T210

changes the setpoint temperature to 21.0 C

How does it work?

concordia2

(see picture above) The yellow pipe  goes through the floor to get cool air from the outside, with a manual emergency valve and the servocontrolled flow control valve (the black block below the white box).

The white box connects the pipe to a standard 8cm computer fan that blows the air inside the instrument enclosure. the control system is also inside the instrument box, the green led indicates cooling in progress.

concordiashield

The custom shield (see pic above) is used to interface the Arduino with the various system components. The big transistor (2N3904) drives the cooling fan, the two smaller ones (2N2222) control the green/red led that signals cooling or heating. The voltage regulator provides the ~8v needed by the arduino board (could work without, but at 12v it overheats a lot…)

The heater is made by three transistors in series mounted on heat sinks with a small fan each, and is driven directly by a digital output pin on the arduino, the servo on the flow valve is also driven directly by a pwm output.

Download the Arduino Sketch here.

 

The Original Seven (Eight?) Segment Display

via Hackaday » hardware

The seven-segment LED display is ubiquitous. But how old do you think the fundamental idea behind it is? You nixie tube fans will be thinking of the vacuum-tube era, but a reader sent us this patent filed in 1908 where [Frank W. Wood] builds a numeric display with plain-vanilla light bulbs, slots cut in wood, and lots of wires.

The OCR on the patent is poorly done — you’re going to want to download the PDF and read it locally. But as it states in the patent, “Referring again to Fig. 1, the novel arrangement of the lamp compartments will be readily understood.”

Technically it’s not a seven-segment display at all. [F.W. Wood] designed these really nice-looking “4”s with the diagonal heads, and so he needed eight segments per digit. But the basic idea shines through, if you pardon the pun.

The other figures demonstrate the machine that’s used to send the signals to light up the lights. It’s a rotating drum with the right contacts on the bottom side to make connections and turn on the right lights at the other end. Low tech, but it’s what was available at the time.

We’re stoked that we’re not responsible for wiring this thing up, and we’re a bit awed by how old the spirit behind one of our most ubiquitous technologies is.

Thanks to [mario59] for the nostalgic tip!


Filed under: hardware