Miscellaneous category

Windows PC Lock/Unlock Using RFID

by kksjunior @ instructables.com:

How often have you felt tired of typing in the password to unlock your PC/laptop every time it got locked? I’m used to locking it down quite a number of times, everyday, and nothing is more annoying than typing the password/pin over and over again, every-time I want to unlock it. When the need for something becomes essential, you are forced to find ways of getting it. As the saying goes, “necessity is the mother of invention”, the lazy mind in me started to think of an easy and a cheap way to unlock my personal Computer/Laptop every time I had to lock it. As I went through my stuff I found a RC522 RFID module. That’s when I decided to make an RFID system

Windows PC Lock/Unlock Using RFID – [Link]

VO2 Based Mott - MEMS Mirror Actuator

Researchers Developed VO2 Based MEMS Mirror Actuator That Requires Very Low Power

A joint research by the US Air Force Research Laboratory Sensors Directorate and Michigan State University have developed micro-electromechanical systems (MEMS) actuator based on smart materials, specifically vanadium dioxide (VO2). In the room temperature, Vanadium dioxide exhibits the Mott transition. It is a not-well-understood phenomenon known to occur in transition metal chalcogenides and transition metal oxides.

VO2 Based Mott - MEMS Mirror Actuator
VO2 Based Mott – MEMS Mirror Actuator

The research team was able to use VO2 thin films for making complex mirror support structures to create a programmable tilting mirror. Transition-metal oxides like VO2 require little energy to drive the transition and less than more conventional actuation technologies. This enables implementation of transition-metal oxide based MEMS in battery powered and mobile devices.

When an input voltage of 1.1V is applied, the mirror platform achieves the maximum vertical displacement of 75 microns. The average power consumption per mirror actuator is 6.5mW and the total power consumption is 26.1mW for the entire device. The Mott-MEMS actuator mirror showed vertical movements and tilt angles of 75 micrometers and 5.5 degrees, respectively.

While testing, vanadium dioxide (VO2) displayed hysteric behavior or memory effect. That means the current response to externally applied electrical force is dependent on the previous response. Such behavior will let the researchers predict its response nature for certain electrical signals and they can program the actuators to generate different types of responses.

Nelson Sepulveda, a professor of electrical and computer engineering at Michigan State University, said in a statement issued by Wright-Patterson Air Force Base,

The actuation of such devices using smart phase-change materials represents a new operating principle that enables their programming and reduces power consumption.

The study opened a new door in the development of MEMS mirror actuation technology, which could incorporate the use of the hysteresis of smart materials like VO2 for programming tilt angles and vertical displacements in MEMS mirrors. The researchers are focusing on developing programmable MEMs mirrors and improving the design to achieve more precise control and larger movements.

FPGAs For MCU Guys

by Max Maxfield @ eeweb.com:

A little while ago, it struck me that I was getting tired of explaining what FPGAs are and how they work their magic to those of my chums who — thus far — have worked only with microcontrollers (MCUs), so I decided to write a three-part mini-series of articles to offer as an introduction.

FPGAs For MCU Guys – [Link]

Call for Makers: Hackaday Prize for Social Impact Projects

In patnership with Digi-Key, Supply Frame and Microship, Hackaday is calling for the curious, the creative, and the determined who are working to create social change in order to transform the world using their hardware and programming knowledge in addition to scientific, design, and mechanical abilities. This contest by Hackaday will encourage people innovate projects that can impact in people lives.

All you have to do is designing an impactful project that suits you, or collaborate with a team to do it. You can create things like reliable utensils for the disabled, a way for denizens to find clean drinking water in rural villages, refreshable braille displays for image text and a smart home to build a sustainable community. Or go beyond that and create something that has never been seen before. The purpose of the contest is to encourage participants to develop solutions to address technology issues facing humanity today.

With the global collaboration behind this contest, the total prizes will reach $250,000 and they will be divided as following: $120,000 goes to top 120 finalists ($1,000 each), $50,000 Grand Prize, $30,000 Best Product Prize, $20,000 2nd Place, $15,000 3rd Place, $10,000 4th Place and finally a$5,000 5th Place.

The first stage of the Contest will consist of five (5) Challenge Rounds. Participants may enter the Contest during any of the Challenge Rounds. Up to twenty (20) entries from each Challenge Round will be chosen to advance to the final round. Participants must complete the requirements for at least one (1) Challenge Round to be eligible for the final round. An entry may be submitted to any or all of the Challenge Rounds as long as it meets the requirements for each Challenge Round in which it is submitted. All submissions must be in English and must comply with any specified requirements.

Challenge Round 1: (Get Started: Design Your Concept.)

Entry period begins 7:01 a.m. P.D.T on March 20, 2017 and closes 7:00 a.m. P.D.T on May 1, 2017. This round is for showcasing your idea, hacks and logs and presenting the problem and how will your project solve it.

Challenge Round 2: (Internet of Useful Things :: IuT ! IoT)

Entry period begins 7:01 a.m. P.D.T on May 1, 2017 and closes 7:00 a.m. P.D.T on June 12, 2017.
Let’s take Internet of Things and make it practical for everyday life. Internet of Useful Things projects showcase a way to build a better tomorrow with the data you track and analyzeChallenge

Round 3: (Wheels, Wings and Walkers)

Entry period begins 7:01 a.m. P.D.T on June 12, 2017 and closes 7:00 a.m. P.D.T on July 24, 2017. This round is for building things that move, so the objective of the project is movement and support for things that help move humanity forward.

Challenge Round 4: (Assistive Technology)

Entry period begins 7:01 a.m. P.D.T on July 24, 2017 and closes 7:00 a.m. P.D.T on September 4, 2017.  Assistive technology projects ensure a better quality of life for the disabled and enhance learning, working, and daily living.

Challenge Round 5: (Anything Goes)

Entry period begins 7:01 a.m. P.D.T on September 4, 2017 and closes 7:00 a.m. P.D.T on October 16, 2017. No reservation, no theme, no topic. it is up to you to build on your idea that resonates with you and encompasses the spirit of making. Build whatever you think would benefit humans and the world we live in.

Best Product

To be eligible for Best Product the product must not have received more than $2,000,000 in funding within the life of the product. The sum of the product’s dimensions (width + height + depth) must total 36 inches (91.44 centimeters) or less. Best Product Final Round. By 1:50 p.m. P.D.T. on October 21, 2017

It’s time to leverage your talent and find solutions to address a problem facing humanity today. With a new technical design challenge every 6 weeks, you are expanding the frontiers of knowledge and engineering.

In order to bootstrap your project before completing your final application of this contest, Hackaday now gives you the chance to participate in a public voting and win up to $200. Just start your entry to get access to this.
Check the rules of the contest to make sure that your country is eligible to apply. Also check this page to know more details about the contest.

Amplifier requires no dc bias

john guy @ edn.com writes:

Intrinsically capacitive transducers and other high-impedance signal sources usually require ac coupling and a buffer amplifier to condition the signal for further processing. Buffers take many forms, but most of them compromise signal quality through the use of external resistors that provide a dc path for the input bias current. Recent improvements in op-amp technology allow ac-coupled inputs without the need for bias resistors.

Amplifier requires no dc bias – [Link]

Simple negative resistance oscillators

Bob tipped us about a simple oscillator that uses negative resistance:

Normally -according to the Ohm’s law– when the applied voltage is increasing, the current is increasing too, however some components can break this law. When the voltage increases, current decreases. This is called negative resistance.

One of the most know element that exhibits this behavior is a tunnel diode. Once very promising, today it isn’t widely used in popular designs and occupies a niche in microwave applications. It’s a bit challenging to get one, fortunately simple circuits that have negative resistance feature can be build from popular discrete elements. One of them I will present today.

Simple negative resistance oscillators – [Link]

Latching Relay Module

govindanunni@ instructables.com has build a latching relay module using 555 timer IC that is also able to interfaced to a microcontroller.

In this instructable I will show you how to use a non-latching relay as a latching bistable relay by designing a simple electronic module which is powered by an external power source. One can use this module for many other projects and it’s intentionally made portable so that one can easily carry it around. Moreover it has many other useful features which provides it many additional functionalities.

Latching Relay Module – [Link]

Digital Potentiometer using Optical Encoder – 10KOhms

The primary application of the project is to replace the mechanical potentiometer with optical encoder which is long life, accurate, smooth in operation. The simple project has been designed around LS7184 quadrature clock converter IC from LSI semiconductor, AD5220-10 Digital potentiometer from Analog Devices, and optical encoder from Burns.

Quadrature clocks derived from optical encoder, when applied to the A and B inputs of the LS7184, are converted to strings of Clock and an Up/down direction control. These outputs interfaced directly to AD5220-10 Digital Potentiometer IC.

The AD5220-10 contains a single channel, 128 positions, and digitally-controlled 10K ohms variable resistor (VR) device. This device performs the same electronic adjustment function as a potentiometer.

Digital Potentiometer using Optical Encoder – 10KOhms – [Link]

The Making of a Cooled CMOS Camera

landingfield.wordpress.com shows us their progress on how to make a cooled CMOS camera able to be used for astrophotography.

In the last post, I uncovered a bug in the Vivado implementation which accidently removes the DIFF_TERM from my input buffer. With that problem solved, I picked up the project again with a goal to achieve high speed imaging. Now I’m going to cover the design principal and its intermediate steps to achieve it.

The Making of a Cooled CMOS Camera – [Link]

LC-04 4 Channel Logic Converter 3.3V – 5.0V

If you have ever tried to connect a 3.3V device to a 5V system, you know what a challenge it can be. The LC-04 bi-directional logic level converter is a small device that safely steps down 5V signal to 3.3V and steps up 3.3V to 5V at the same time. In this instructable, mybotic explained the procedure to use the LC-04 bi-directional logic converter.


The LC-04 module offers bi-directional shifting of logic level for up to four channels. The logic level HIGH (logic 1) on each side of the board is achieved by 10K Ω pull-up resistors connected to the respective power supply. This provides a quick enough rise time of logic level to convert high frequency (400KHz I²C, SPI, UART etc.) signals without delay.

This module has the following features:

  • Dual-supply bus translation :
    • Lower-voltage (LV) supply can be 1.5 V to 7 V
    • Higher-voltage (HV) supply can be LV to 18 V
  • Four bi-directional channels
  • Small size: 0.4″ × 0.5″ × 0.08″ (13 mm × 10 mm × 2 mm)
  • Breadboard-compatible pin spacing

    The bi-directional level-shifting circuit
    The bi-directional level shifting circuit

The Pinout:

The LC-04 logic level converter has two types of pins:

  1. Voltage input pins :
    • 2 pins (GND and LV) on Low Voltage  side
    • 2 pins (GND and HV) on High Voltage  side
  2. Data channels :
    • 4 pins (LV1, LV2, LV3, and LV4) on Low Voltage  side
    • 4 pins (HV1, HV2, HV3, and HV4) on High Voltage  side

Pin HV and LV set HIGH (logic 1) logic level on High voltage side and Low voltage side respectively, with respect to the GND.

Data channel pins shift logic levels from one voltage reference to another. A low voltage signal sent into LV1, for example, will be shifted up to the higher voltage and sent out through HV1. Similarly, a high voltage signal sent into HV1 will be shifted down to the lower voltage and sent out through LV1.

LC-04 Bi-directional logic level converter pinout
LC-04 Bi-directional logic level converter pinout

Parts List:

  1.  LC-04 4 Channel Logic Level Converter
  2. Arduino Uno Board and USB Cable
  3. Breadboard
  4. Crocodile Clip (optional)
  5. Multimeter

The Wiring:

The wiring is pretty simple. You may even omit the breadboard by making end-to-end connections. Two types of connections are required:

  1. Pin connection to shift down (5V to 3.3V)
  2. Pin connection to shift up (3.3V to 5V)
Pin Connection to Shift Down:
  1. LV to 3.3V
  2. LV’s GND to multimeter’s black probe
  3. LV3 to multimeter’s red probe
  4. HV to 5V
  5. GND to UNO’s GND
  6. HV3 to Digital Pin 4
Logic level shift down using LC-04 logic level converter
Logic level shifting down using LC-04 logic level converter
Pin Connection to Shift Up:
  1. LV to 3.3V
  2. LV’s GND to UNO’s GND
  3. LV3 to Digital Pin 4
  4. HV to 5V
  5. GND to multimeter’s black probe
  6. HV3 to multimeter’s red probe
Logic level shifting up using LC-04 logic level converter
Logic level shifting up using LC-04 logic level converter