Ultrasonic Atomizer

This reference design is a simple ultrasonic atomizer that helps fight against respiratory diseases. Atomizer is like nebulizer, it is just that nebulizer takes time to deliver liquid to mist. However, both undergo almost the same process. This medical ultrasonic atomizer circuit is composed of power supply circuit, ultrasonic oscillator and atomizer circuit. It specifically uses the TE connectivity’s fuse for overcurrent protection.

The device works when electrical energy is transmitted to piezoelectric transducer within the converter, where it is changed to mechanical vibrations. This ultrasonic vibrations are intensified and focused at the tip where the atomization takes place. The liquid travels through the probe and spreads out and the oscillating tip disintegrates the liquid into micro droplets that forms a low velocity spray.

This simple atomizer is widely used for medical applications. It uses high frequency vibrations to aerosolized the medication into a fine mist. It is commonly used for the treatment of cystic fibrosis, asthma and other respiratory diseases.

Ultrasonic Atomizer – [Link]

nodeLHC – ESP8266 development board

nodeLHC_01-1024x683-600x390

Pedro Minatel shared us his ESP8266 development board project – nodeLHC:

This board was developed at the Campinas Hacker Lab in Brazil during our weekly IoT meetings. This layout and schematic was developed by Leandro Pereira.
The idea was to develop a easy to use board and to learn how to use this magnificent WiFi module.
We are not selling it but you can build your own board if you want!!!
This board is full compatible with nodeMCU, Arduino IDE, native development and any other firmware avaliable.

nodeLHC – ESP8266 development board – [Link]

Get rid of unpleasant odors easily and effectively

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USM-MEMS-VOC module evaluates rate of air pollution by contaminants such as cigarette smoke and cooking odors and allows control of air ventilation system on demand.

Modul USM-MEMS-VOC is based on the innovative and highly stable TGS 8100 MEMS semiconductor sensor TGS8100 from Figaro. In the presence of detectable gas, sensor resistance decreases depending on gas concentration in the air. New technology allows very rapid response to gas concentration change. The USM-MEMS-VOC reacts within 8 seconds.

The module evaluates ratio of sensor resistance in clean air (base level) to sensor resistance in polluted air and calculates air quality in range 0 to 100%. It communicates through UART interface. Besides that it provides PWM signal (185Hz) with pulse width proportional to air quality and three binary outputs which turns on when air quality reach 25%, 50% and 75%.

The module allows using of external I2C temperature/humidity sensor for measuring and also to temperature/humidity compensation of TGS8100. USM-MEMS-VOC and TGS8100 can be found in our standard stock offer.


Get rid of unpleasant odors easily and effectively – [Link]

Overheat/Overcooling Circuit Breaker

This project automatically switches off the electrical flow in event of excess heating or excess cooling thus protecting the circuit from damage using NXP NCX2220GU. The comparator guarantees to operate at low voltages which makes this device convenient for use in 5 V systems and has a typical internal hysteresis of 9 mV that allows for greater noise immunity.

For overheat circuit breaker, reference is set to a higher value. An NPN transistor is used to drive the relay since the initial output current of the comparator is not sufficient to drive RY1. When temperature is below the reference set, the output of the comparator will be low then the transistor is in the cut off state and consequently relay does not work. When temperature goes beyond the set reference value, the output of comparator becomes high. Thus biasing the transistor Q1, activating the relay and breaking the external circuit. For overcooling circuit breaker, reference is set below the surrounding temperature and PNP transistor is used. In default state, output of comparator is high but PNP transistor works as not gate as it does not gets biased at high voltage and consequently relay does not work. When temperature becomes lower than the set value, then output of comparator becomes low thereby biasing PNP transistor. Thus activating relay and breaking external circuit.

Overheat/overcooling circuit breaker has the primary objective of cost efficiency in providing circuit protection. Unlike a fuse, which operates once and then must be replaced, a circuit breaker can be reset with no cost associated either manually or automatically to resume normal operation. Applications include isolation for all or part of the IT network switching rooms, thereby facilitating maintenance and protection for plants (transformers, generators, uninterruptible power supplies, and cables) from damage in the event of overcurrents.

Overheat/Overcooling Circuit Breaker – [Link]

LSM6DS3H – New 6-axis motion sensor from STMicroelectronics

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by Martin Cooke @ elektormagazine.com:

The latest MEMs device from STMicroelectronics is said to be the world’s most advanced six-axis motion-sensor device designed to support image stabilization in smartphones, tablets and digital still cameras. The LSM6DS3H combines a 3-axis gyroscope and 3-axis accelerometer together with an Ultra Low Power processing IC to provide a System in Package using low power consumption and packaged in a LGA-14L 2.5 x 3.0 mm outline.

LSM6DS3H – New 6-axis motion sensor from STMicroelectronics – [Link]

Temperature controlled coolbox

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by nusnel @ instructables.com:

For my monthly maker column in Dutch newspaper “De Volkskrant”, I made a coolbox in which you can control the temperature in three separate compartments to keep craft beer at just the right temperature.

The contraption I build uses three Peltier-elements to cool, an old desktop computers power source, an LCD to show both the measured and the set temperature and finally an Arduino to tie it all together.

Temperature controlled coolbox – [Link]

Arduino Time-Lapse Panorama Controller

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by oliverb @ instructables.com:

The Arduino controls a Geared Stepper Motor 28BYJ-48 via a ULN2003 Stepper Motor Driver Board. The 4×20 I2C LCD display and 5 micro switches form the interface to the Arduino. The controller has a Manfrotto 200PL-14 quick release tripod mount for attachment to my tripod and other mounting hardware fitted with a Manfrotto 323 Quick Release Clamp Adapter. Power is provided by a 50000mah USB Power Bank Battery Pack.

Arduino Time-Lapse Panorama Controller – [Link]

Basic Types of Diodes

In this article we will discuss about the various types of diodes, their working principle and their common uses. We will cover many common diode types, such as P-N junction diode, Zener diode, Schottky diode, LED and laser diodes, photo diode, varactor diode, avalanche diode, PIN diode etc. Feel free to leave a comment with other types of diodes you know.

P-N Junction Diode

pn_junction_diode

This is the most common type of diode and acts as one way gate to current flow. The current flows from anode (A) to cathode (C) and comes in two types depending on the material used, silicon and germanium. They both need a forward-bias voltage to contact which is in the range of 0.6-1.7V for silicon and 0.2-0.4V for germanium. Common uses are: voltage rectification, transient suspension, voltage multiplication, voltage regulation etc.

Zener Diode

zener_diode

Zener diode acts like a p-n junction diode if forward-biased and conducts from anode (A) to cathode (C) but will also conduct in the opposite direction if the applied voltage exceeds the zener’s breakout voltage Vz. Common breakout voltages are 1.2V, 3V, 5.1V, 6.3V, 9V, 12V etc. Common uses are: voltage regulation, waveform clipping, voltage shifting, voltage reference etc. Often they are used in series and with opposite directions with p-n junction diodes to balance the temperature coefficient response.

Schottky Diode

schottky_diode

This kind of diodes have similar operation with p-n junction diodes but are constructed with metal semiconductor junction instead of a p-n junction. They have a lower forward voltage drop (0.15-0.45V) than p-n junction diodes and way lower junction capacity that results for quicker switching times. Common uses are: low loss rectification, high frequency applications, RF applications, switchmode power supplies, mixers and detectors.

LED and Laser Diodes

led_laser_diode

Light emitting diodes (LED) produce light when forward biased and they come in many different types depending on wavelength emitted (infrared, visible light and ultraviolet), power output, size and material used. A typical forward voltage is 1.7 to 4V and their wavelength spectrum is about 40nm wide. They are often used as indicators and for lighting purposes. In contrast laser diodes have a much narrower spectrum of about 1nm and fast response times and are used in fiber optic communications, CD/DVDs, barcode readers, medical uses etc.

Photo Diode

photo_diode

Photo diodes are able to generate current when exposed to light and current flow from cathode (C) to anode (A). When light intensity increases the current passing thought the diode also increases and they have fast response time in terms of ns. They are not as sensitive as phototransistors but they have good linearity making them ideal in use on simple light meters. Common uses are in photometry, solar cells and optical communications.

Varactor Diode

varactor_diode

Varactor diodes are used as voltage controlled capacitors. The capacitance decreases as the reverse-bias voltage on the diode increases. We can find them on PPL (Phase locked loop), FLL (Frequency locked loop) circuits, general RF applications and tuning receivers. The junction has a capacitance in the range of pF for small variations on reverse-bias voltage.

Avalanche diode

avalanche_diode

Avalanche diodes are similar to Zener diodes, they contact when reverse biased and the reverse bias voltage exceeds the breakdown voltage. They may be similar to Zener diodes but the breakdown occurs using a different mechanism, the avalanche effect. Another difference is that they have opposite temperature coefficients. They are used in voltage references, protection, RF noise generation etc.

PIN Diodes

PIN_diode

PIN diodes have a central un-doped region between P and N regions and they are used as RF and microwave switches. For high frequency signals PIN diode acts like a variable resistor whose value is depended on the applied dc forward-biased voltage. So, for high DC forward bias its resistance is less than an Ohm but in low forward bias the resistance is in the kOhm range.

There are also some other types of diodes available such as IMPATT, Gunn, Tunnel which are used for special purposes at high frequencies, for example on amplifiers and oscillators. The physics of such diodes is complex and beyond the scope of this article. I hope you get an idea of the basic types of diodes available and feel free to leave a comment.

Driving LEDs

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Emanuele @ dev.emcelettronica.com published an article on how to drive LEDs:

The LEDs (Light Emitting Diode) are diodes whose basic characteristic is the ability to emit light when they are passed through a current that flows from P to N region. At each recombination between the charge carriers (electrons and holes), on PN junction region, a photo emission is generated, and the total quantity of emitted photons, and therefore the light intensity, is proportional to the current intensity that passes through them. The emitted light has a spectrum – wavelengths distribution – that is defined according to the materials used in the realization of the diode PN junction, although it partially depends on the current intensity and on the junction temperature.

Driving LEDs – [Link]

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