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]
Project has been designed to record & playback multi voice massages using Winbonds ISD1740 IC. Messages are stored in flash memories made in unique Multilevel Storage Technology (MLS). Circuit provides high quality audio recording and simple operations. Circuit operates in dual mode standalone or micro-controller SPI mode. Onboard tactile switches for standalone mode and 10 (2×5) pin box header connector for SPI mode. 26 to 80 Seconds voice massage recording capacity.
– Supply 2.4 to 5 VDC (5 VDC @ 100 mA)
– 26 to 80 Seconds selectable voice recording capacity
– Selectable sampling rates 11.5 KHz, 7.8 KHz, 6.4 KHz, 5.3 KHz, 4.5 KHz
– Directly drive 8 Ohms speaker or typical buzzer
– Analog audio out to driver external audio amplifier
– Digital volume control via onboard tactile switch
– Dual mode operation stand alone or micro-controller
– SPI Interface (4 wire serial interface)
– 10 (2×5) Pin box header for SPI interface
– Full control on memory and analog path configuration audio input, output and mix in SPI mode
– Automatic power-down after each operations cycle (standalone mode)
– Onboard tactile switch for Record, Play, Erase, FWD, Volume control, Reset and Feed-Through
– Onboard power indication, record play indication
– Voice message fed in via microphone or analog signal in
– ISD1740 provides a PWM class D speaker driver and speaker output simultaneously –
– 100 Years message retention
– 100,000 Record cycles
– Four mounting holes of 3.2 mm each
– PCB dimensions 80 mm x 76 mm
20 to 80 Seconds Voice Record Playback with SPI control – [Link]
The Mini Audio Amplifier project is a good choice for battery operated gadgets. It is based on Texas instruments LM386 IC, provides high quality Audio.
– Wide power supply input 6 to 12 VDC
– 500 mW output @ 8 Ohms load
– Takes standard audio signal as input
– Low quiescent current drain 4 mA IC
– The quiescent power drain is only 24 mW when operating from 6 VDC
– Onboard preset for volume adjust
– Header connector for connecting power supply, audio signal and speaker
– Onboard power indication LED
– On/Off PCB mounted slide switch for power supply
– Four mounting holes of 3.2 mm each
– PCB dimensions 41 mm x 41 mm
Mini Audio Amplifier – [Link]