ESP8266 controlled with Android app (MIT App Inventor)

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Rui Santos from Random Nerd Tutorials tipped us with his latest tutorial on how to build an Android app using the MIT App Inventor software that allows you to control the ESP8266 GPIOs:

ESP8266 controlled with Android app (MIT App Inventor) – [Link]

How to Select a Resistor

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In this guide Sanket Gupta @ octopart.com explains how to select a resistor from a range of common resistor types.

In this blog, we will explain all the different types of resistors, their merits and demerits, and popular applications. We have included some recommendations for commonly used resistor series with high supply chain availability from the Common Parts Library and Seeed Studio’s Open Parts Library, and have linked to pre-created search on Octopart.

How to Select a Resistor – [Link]

Dual DC Motor Driver For Robot with L298

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Dual Motor L298 H-Bridge Control project can control two DC motors connected to it. The circuit is designed around popular dual H-Bridge L298 from ST. This board can be configured to drive a single motor with high current rating also. This can be achieved with the help of jumpers on the board. An onboard 5V regulator can take a maximum of 18V of DC input. Should you wish to drive this board with higher voltage then 18V, you will need to connect a external 5V regulated source to the logic circuit. For this you will need to remove J-5V. This board can fit in any small toy or robot due to small size and very low profile. L298 IC is mounted under the PCB in horizontal position to make board small and low profile to fit any small robot. On board 5V regulator can be used to power up external Micro-Controller board as well as internal logic supply.

Features 

  • Motor supply: 7 to 46 VDC
  • Open J-5V Jumper if Input Motor Supply is above 18V ( Required External 5V for Logic)
  • Control Logic Input: Standard TTL logic level
  • Output DC drive to motor: up to 2 A each (Peak)
  • On Board 5V Regulator (Close J-5V to Use On Board 5V Regulator)
  • Enable and direction control pins available
  • External Diode Bridge for protection
  • Heat-sink for IC

Dual DC Motor Driver For Robot with L298 – [Link]

Review & Teardown of a cheap GPS Jammer

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phasenoise has posted his teardown of a cheap GPS Jammer. This GPS jammer generates a 1575.42 Mhz interference to prevent your GPS unit from receiving correct positioning signals.

Generally, “jammers” — which are also commonly called signal blockers, GPS jammers, cell phone jammers, wifi jammers, etc. are radio frequency transmitters that are designed to block, jam, or otherwise interfere with radio communications.

Review & Teardown of a cheap GPS Jammer – [Link]

Teardown: 12V AC adapters

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Michael Dunn has done three teardowns of the worst 12V adapters and what he found is interesting.

Yes! Can you believe it? This board used to be in another adapter housing, or more likely, in an end-product. It seems Chinese manufacturing has sunk to a new low: repackaging used and/or surplus power supplies. On the plus side…recycling.

Teardown: 12V AC adapters – [Link]

Solar Cell IV Curve Tracer

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This instructable shows how to build a photovoltaic cell curve tracer using Arduino and OPA549S OPAMPS.

This projects shows how to create an IV (Current and Voltage) Tracer that can be used to teach the electrical characteristics of a solar panel.

This project was created as part of an Electrical and Computer Engineering capstone project at The Ohio State University.

Solar Cell IV Curve Tracer – [Link]

USB curve tracer for NPN transistors

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Dilshan Jayakody documented his USB port base NPN transistor curve tracer project:

Curve tracer is an electronic test instrument to analyze the characteristics of transistors and other discrete semiconductors. In this post we construct USB base curve tracer to analyze properties of NPN transistors. This curve tracer is build around Microchip’s PIC18F4550 MCU and it use simple Windows based GUI application to plot captured data of a transistor.

USB curve tracer for NPN transistors – [Link]

Basic Switching Voltage Regulator Tutorial

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James Lewis @ baldengineer.com discuss about switching regulator types and uses.

A switching voltage regulator is one of my favorite circuits. In school, they were the first circuits I built where I understood how transistors worked. In fact, they were the first circuit I saw an inductor being useful! Switching regulators are incredibly efficient when designed properly. Of course, this detail about design is important.

Basic Switching Voltage Regulator Tutorial – [Link]

Arduino Body Thermometer + LCD I2C

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This is a body thermometer using a thermistor sensor, Arduino and LCD display.

I’ve decided to provide a funny Arduino concept thermometer in case its the middle of the night, pharmacies are not working, you are not feeling well and you want to check your body temperature. If you have Arduino by your side, this is a life saver!

Arduino Body Thermometer + LCD I2C – [Link]

Simple circuit provides precision ADC interface

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Moshe Gerstanhaber @ edn.com provides an simple ADC interface using instrumentation amplifier IC.

Real-world measurement requires the extraction of weak signals from noisy sources. High common-mode voltages are often present even in differential measurements. The usual approach to this problem is to use an op amp or an instrumentation amplifier and then perform some type of lowpass-filtering to reduce the background noise level.

Simple circuit provides precision ADC interface – [Link]