by T.K. Hareendran:
Here is a tried and tested sample circuit of a Li-Ion battery charger that can be used to charge any 3.7V Li-Ion battery using a 5VDC (USB, Solar Panel…) power supply. At the heart of the circuit is one microchip MCP73831, available in SOT-23-5 package. MCP73831 is a highly advanced linear charge management controller for use in space-limited, cost-sensitive applications. This IC employs a constant current/constant voltage charge algorithm with selectable preconditioning and charge termination.
3.7V Li-Ion Battery Charger Circuit – [Link]
14W Stereo audio power amplifier build around LM4730 IC. The LM4730 is stereo audio amplifier capable of delivering typical 14W per channel of continues average output power a 4 Ohms or 8 Ohms load with less than 10% THD+N from 20Hz to 20Khz frequency. Each amplifier has an independent smooth transition fade-in/out mute and a power conserving standby mode which can be controlled by onboard slide switches.
The LM4730 has short circuit protection and thermal shutdown feature that is activated when the IC temperature exceeds 150 centigrade. The LM4730 also has under voltage lock out feature for click and pop free power off and on. Amplifier required proper heat sink.
14W Stereo Audio Amplifier – [Link]
by dkschottt @ instructables.com:
Being new to Arduino I was a bit overwhelmed by the different ways to do things. So this is what I came up with!
I am using an Arduino UNO R3 clone but the connections I believe are the same for most Arduino’s or can be easily modified for your particular model. This project is the beginning of a UROV that I am building from the ground up and this is my first attempt to work with Arduino. I do not want to turn my UNO into a webserver if I can avoid it because of the shortage of memory and this project is just a few of the sensors that I want to use for my project. I am going to start out by using the premise that my project will eventually use RS485 to communicate serially from my UNO to the PC via a tether.
Getting Arduino data to a web Page – [Link]
At the 2015 Mobile World Congress in Barcelona, Spain, the leading sensor manufacturer Sensirion will present a new multi-pixel gas sensor, plus a new barometric pressure sensor. Both new sensors, which rank among the smallest yet most accurate in their class worldwide, are capable of measuring indoor air quality (IAQ), the gases in a person’s breath, and barometric air pressure, as required for indoor navigation applications. The new sensors complement Sensirion’s existing product offering for wearables, smartphones, tablets, and the Internet of Things (IoT), and confirm the company’s status as the only sensor manufacturer to offer a complete solution all the way from sensor to cloud. With its trusted humidity and temperature sensors already established on the market, Sensirion is now expanding its range of environmental sensors to include gas and pressure sensors.
Sensirion presents the smallest and most accurate Gas and Pressure Sensors – [Link]
One of the simplest digital modulation schemes in current use is the Frequency-shift keying (FSK). FSK is similar to Frequency Modulation or FM except that the modulating signal is a binary pulse stream that varies between two discrete voltage levels rather than a continuously changing analog waveform. In FSK, two discrete frequencies are used to represent the binary digits 0 and 1.
The heart of the circuit consists of two Wien-bridge oscillators built using a dual op amp LM1458, for the two frequencies. The two frequencies are enabled corresponding to digital data using two switches in HEF4016BP. The control lines of these switches are logically inverted with respect to each other using one of the switches in HEF4016BP as an inverter, so as to enable only one oscillator output at a time. The digital bit stream is used to control the analog switches as shown. Since the switching frequency limit of HEF4016BP is 40 MHz, high-data rates can be easily accommodated. This method comes in handy when expensive FSK generator chips are not readily available; also, the components used in this circuit are easily available off the shelf and are quite cheap.
FSK was originally used to transmit teleprinter messages by radio (RTTY) but can be used for most other types of radio and landline digital telegraph. Currently, FSK is commonly used in Caller ID and remote metering applications.
Low-cost FSK Generator – [Link]
Standalone Linear Li-Ion battery charger with thermal regulation in ThinSOT application note (PDF!) from Linear:
The LTC4054 is a single cell lithium-ion battery charger using a constant-current/constant voltage algorithm. It can deliver up to 800mA of charge current (using a good thermal PCB layout) with a final float voltage accuracy of ±1%. The LTC4054 includes an internal P-channel power MOSFET and thermal regulation circuitry. No blocking diode or external current sense resistor is required; thus, the basic charger circuit requires only two external components. Furthermore, the LTC4054 is capable of operating from a USB power source.
App note: Standalone Linear Li-Ion battery charger with thermal regulation – [Link]
The bq2510x series of devices are highly integrated Li-Ion and Li-Pol linear chargers targeted at space-limited portable applications. The high input voltage range with input overvoltage protection supports low-cost unregulated adapters.
The bq2510x has a single power output that charges the battery. A system load can be placed in parallel with the battery as long as the average system load does not keep the battery from charging fully during the 10 hour safety timer.
The battery is charged in three phases: conditioning, constant current and constant voltage. In all charge phases, an internal control loop monitors the IC junction temperature and reduces the charge current if an internal temperature threshold is exceeded.
BQ25101H – 250-mA Single Cell Li-Ion Battery Charger, 1mA termination, 75nA Battery leakage – [Link]
In this video we are going to build an Arduino Uno clone in a breadboard using only 5 parts.
Arduino Uno (ATMEGA328P) on a breadboard – [Link]
What’s inside the Keithley 2400 Source Measure Unit?
EEVblog #718 – Keithley 2400 SMU Teardown – [Link]
by Martin @ harizanov.com:
The WiFi SSR board project changed a bit and I use classical relays instead of SSRs now. The reason is that SSRs tend to get quite hot when switching larger loads, and the 8A relays I last used actually could be used for max 2.5A load switching with no heat sink. The high quality relays I now use allow 10A load switching and are rather quiet. I also changed the design a bit so that it would fit in a box (DIN rail compatible) for increased safety.
WiFi Thermostat with weekly scheduler – [Link]