Nathan Spallone and Zhiyuan Teo from Cornell University designed a wireless storage with biometric protection as their final project for Bruce Land‘s ECE 4760 course. Their design uses a fingerprint scanner for authorization and an induction coil for wireless charging. The user can authenticate into the storage system by simply placing a thumb on the fingerprint sensor and can sync the drive to a home station wirelessly using an nRF24l01+ transceiver module. The home station also usesan nRF24l01+ transceiver module along with an Arduino board, which is connected to a PC over USB. They also wrote a PC application to allow the user to read and store data on the device over the RF link.
Wireless storage with biometric authentication
The base station also has an inductive charger that the user can place the device on to charge wirelessly, without the hassle of plugging anything in. 20 fingerprints can be stored on the device, and each fingerprint has a separate logical volume that the corresponding user can utilize as their own private storage space.
The device has a 1 inch OLED screen that gives the user feedback and information, such as which current user is logged in, and how much storage is being used.
he device is extremely usable. It does not require the nimble action of plugging in a device every time a user wants to manipulate a file, rather it can be activated wirelessly. As well, there are no buttons on the device except for a power switch, and the only actuation needed for operation is touching a finger to a fingerprint scanner. The OLED is monochromatic, thus anyone with any sort of colorblindness will be able to use the device.
David Cook’s new handy LED tester is based on the LM317L adjustable current regulator and consists of a microcontroller and an LCD to display the forward bias voltage across the LED and required series resistance for operation at the user-specified current and circuit voltage.
DIY LED tester
Most projects include at least one LED. Before soldering the LED, how can you determine if the color and brightness meets your needs? After that, how do you calculate the correct value resistor?
Many years ago, I built a handy compact LED testing tool based on the LM317L adjustable current regulator. (You’ll definitely want to click on that link before continuing with this article.) It ended up being one of the most useful tools. In fact, the LED tester sits on a shelf above my keyboard, because I use the tester almost as often as I use my multimeter.
The problem with my original LED test tool is that I need a multimeter to measure the voltage of the LED. And, then I need a spreadsheet to calculate the resistance needed for that LED voltage with a given circuit voltage.
So, I decided to make an improved LED tester with LCD display!
educ8s.tv has posted another great video tutorial on building an Arduino infrared thermometer using the MLX90614 Infrared temperature sensor, which uses the standard I2C protocol to communicate with the Arduino. The measured temperature is displayed on a Nokia 5110 LCD display shield. The device can measure the temperature of an object without any physical contact and with just facing the sensor toward it from a small distance. It can measure temperatures from -70 degrees Celsius to 380 degrees with an of about 0.5 degree at room temperature.
Yves Arbour and Rui Santos describes a concept of building a weather station plus data logger using two ESP8266 modules operating in a server/client configuration. The client ESP8266 measures temperature and other sensor inputs and transmits the data to the server ESP8266, which is connected to a PC through a USB-UART bridge. This ESP8266 weather station records the sensor data to a Microsoft Excel sheet on the PC. They used the Things Gateway PC application by Roberto Valgolio to read/write data to the Excel sheets and to generate real-time graphs of sensor measurements.
DIY prototyping board with regulated power supplies
Prototyping is a useful and powerful method in electronics which lets us analyze a circuit before using it in a system or turning it into a product. In this process we may need a single supply or multiple supplies to power the circuit depending on the type of the application. For example, an op-amp circuit may need a symmetrical supply such as +12V and -12V or a logic circuit may require both 5V and 3.3V at the same time. Some applications may need three or more. This means we should have a bench supply with multiple outputs or multiple bench supplies in the environment. This may not be always possible. This DIY Prototyping Board is designed to provide all the most used supply voltages that a designer will need during prototyping a circuit. The switching power supplies on the board output 3.3V, 5V, 12V and -12V rated at 1A independently. In addition those there are two precise voltage references at 5V and 2.5V provided especially for op-amp based applications.