Tachometer Uses Light, Arduinos

To measure how fast something spins, most of us will reach for a tachometer without thinking much about how it works. Tachometers are often found in cars to measure engine RPM, but handheld units can be used for measuring the speed of rotation for other things as well. While some have mechanical shafts that must make physical contact with whatever you’re trying to measure, [electronoobs] has created a contactless tachometer that uses infrared light to take RPM measurements instead.

The tool uses an infrared emitter/detector pair along with an op amp to sense revolution speed. The signal from the IR detector is passed through an op amp in order to improve the quality of the signal and then that is fed into an Arduino. The device also features an OLED screen and a fine-tuning potentiometer all within its own self-contained, 3D-printed case and is powered by a 9 V battery, and can measure up to 10,000 RPM.

The only downside to this design is that a piece of white tape needs to be applied to the subject in order to get the IR detector to work properly, but this is an acceptable tradeoff for not having to make physical contact with a high-speed rotating shaft. All of the schematics and G code are available on the project site too if you want to build your own, and if you’re curious as to what other tools Arduinos have been used in be sure to check out the Arduino-based precision jig.

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Forth System-On-Chip Takes Us Back to the 80s

For anyone who has dealt with the programming language Forth, odds are good that you picked it up back in the 80s. Since the language is still in use for many applications, though, you might not have this sort of nostalgic feeling for the language that some might have. For that, though, you might want to try out [Richard]’s implementation which simulates the microcomputers of the 80s using this unique language.

The system has an FPGA-based CPU written in Verilog. It runs on a Nexys-3 board and features PS/2 Keyboard input, a VGA output with a VHDL VT100 terminal emulation module, access to the Flash and onboard SRAM, and a UART. With all of that put together it’s virtually a Forth-based time machine. It’s also extremely well documented even if you’re just curious how it works and aren’t planning on building your own.

The project also includes a CPU simulator written in C which can model the entire computer if you don’t have the hardware for building the actual computer. [Richard] also released everything that you’d need to roll out your own Forth computer on the GitHub page. There are other ways of heading way back to the 1980s, though, like using the quirky Parralax Propeller.

Harvesting Energy from the Earth with Quantum Tunneling

More energy hits the earth in sunlight every day than humanity could use in about 16,000 years or so, but that hasn’t stopped us from trying to tap into other sources of energy too. One source that shows promise is geothermal, but these methods have been hindered by large startup costs and other engineering challenges. A new way to tap into this energy source has been found however, which relies on capturing the infrared radiation that the Earth continuously gives off rather than digging large holes and using heat exchangers.

This energy is the thermal radiation that virtually everything gives off in some form or another. The challenge in harvesting this energy is that since the energy is in the infrared range, exceptionally tiny antennas are needed which will resonate at that frequency. It isn’t just fancy antennas, either; a new type of diode had to be manufactured which uses quantum tunneling to convert the energy into DC electricity.

While the scientists involved in this new concept point out that this is just a prototype at this point, it shows promise and could be a game-changer since it would allow clean energy to be harvested whenever needed, and wouldn’t rely on the prevailing weather. While many clean-energy-promising projects often seem like pipe dreams, we can’t say it’s the most unlikely candidate for future widespread adoption we’ve ever seen.

Xbox Needs No TV

If you want a custom video game system, you could grab a used computer, throw an emulator on it, and build yourself a custom arcade cabinet. On the other hand, if you’d rather not deal with emulators, you can always use a console and modify it into your own tiny arcade cabinet using the original hardware. That’s what the latest project from [Element18592] does, using an Xbox 360 Slim and a small LCD screen to make a mini-arcade of sorts.

The build uses a 7″ TFT LCD and a Flexible Printed Circuit (FPC) extension board. The screen gets 12V power from the Xbox and another set of leads are soldered directly to the composite output on the motherboard. The project also makes use of a special switch which can enable or disable the built-in monitor and allow the Xbox to function with a normal TV or monitor.

Admittedly, he does point out that this project isn’t the most practical to use. But it is still a deceptively simple modification to make to the Xbox compared to some of the more complicated mods we’ve seen before. The fact that almost anyone could accomplish this with little more than some soldering is an impressive feat in the world of console mods.

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Hacking a Sonoff WiFi Switch

The ESP8266 platform has become so popular that it isn’t just being used in hobby and one-off projects anymore. Companies like Sonoff are basing entire home automation product lines around the inexpensive WiFi card. What this means for most of us is that there’s now an easily hackable and readily available product on the market that’s easily reprogrammed and used with tools that we’ve known about for years now, as [Dan] shows in his latest project.

[Dan] has an aquaponics setup in his home, and needs some automation to run the lights. Reaching for a Sonoff was an easy way to get this done, but the out-of-the-box device can only be programmed in the simplest of ways. To get more control over the unit, he wired a USB-to-Serial UART to the female headers on the board and got to programming it.

The upgraded devices are fully programmable and customizable now, and this would be a great hack for anyone looking to get more out of a Sonoff switch. A lot of the work is already done, like building a safe enclosure, wiring it, and getting it to look halfway decent. All that needs to be done is a little bit of programming. Of course, if you’d like to roll out your own home automation setup from scratch that can do everything from opening the garage door to alerting you when your dog barks, that’s doable too. You’ll just need a little more hardware.

Making Software Defined Radio Portable

While most smartphones can receive at least some radio, transmitting radio signals is an entirely different matter. But, if you have an Android phone and a few antennas (and a ham radio license) it turns out that it is possible to get a respectable software-defined radio on your handset.

[Adrian] set this up to be fully portable as well, so he is running both the transceiver and the Android phone from a rechargeable battery bank. The transceiver is also an interesting miniaturized version of the LimeSDR, the Lime SDR Mini, a crowdfunded Open Source radio platform intended for applications where space is at a premium. It operates on the 10 MHz to 3.5 GHz bands, has two channels, and has a decent price tag too at under $100.

For someone looking for an SDR project or who needs something very portable and self-contained, this could be a great option. The code, firmware, and board layout files are all also open source, which is always a great feature. If you’re new to SDR though, there’s a classic project that will get you off the ground for even less effort.

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Router Rebooter Eliminates Hassles

Some low-end or older routers might get you a decent WiFi network in your house or apartment, but often these cheaply made devices are plagued with subtle software problems that cause the router itself to become unresponsive after a few days of operating. One solution is to just power cycle the router by hand whenever the Internet disappears, but a better solution is to build something that does that for you.

[Charlie] had this problem as the de facto IT person in his family, and didn’t want to keep getting bothered for such a simple problem. His solution involves a relay, an ESP8266, and a Wemos D1 mini. The device connects to the Internet through the router and occasionally sends out pings to another address. If it can’t ping the address successfully after a certain time period, the device power cycles the router by activating the relay.

Since this isn’t the newest idea out there, there are many ways to solve this problem if you are constantly annoyed by router issues, whether from your own router or from friends and family who treat you as their personal IT department. One solution doesn’t involve any extra hardware at all as long as you have a computer near your router/modem already, and others solve this problem when it happens to the modem rather than the router.

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