In this episode Shahriar explores the world of filters! Starting from a simple lumped RC filter, he briefly covers the theory before moving onto measurement techniques. The bandwidth of the filter is verified experimentally in the time domain. A more complex RLC band-stop filter is also demonstrated with a tune-able inductor which is measured using an RLC meter. Using a Rigol spectrum analyzer with built in tracking generator and an active probe, the frequency response of the filter is measured. Several other packaged filters are also demonstrated and a microwave band-pass filter is disassembled to reveal its internal construction.
Tutorial on Passive Filters, Data Transmission and Equalization - [Link]
Dave explains, shows, and measures a potentially big trap with using high value ceramic capacitors. Is your 10uF capacitor really 10uF in your circuit? You might be shocked! Those humble X7R caps you think are a “stable” dielectric? think again… Class II and above ceramic capacitors can vary their capacitance drastically with DC bias voltage level and also the applied AC voltage.
EEVblog #626 – Ceramic Capacitor Voltage Dependency - [Link]
Due to some intermittent voltage drop issues on the first revision of PowerShield I refactored the design and released a new PowerShield R2 based on the LTC3525 fixed 5V booster that should address this issue. This is a much more expensive chip than the TPS61220, others have used the Linear Technology boosters with success so hopefully it’s more reliable, but price will reflect this. It also means there is no switching between 3.3V and 5V output any more. For 3.3V projects, a Lipo can be connected directly to Moteino and the onboard regulator will provide up to 250mA of current to the Moteino itself and any other peripherals attached.
PowerShield R2 released - [Link]
Blend Micro is an Arduino development board with built-in Bluetooth 4.0 Low Energy (aka BLE or Bluetooth Smart) connectivity targeted at developers using the Arduino platform to design IoT applications. The board uses an Atmel ATmega32u4 micro-controller and the Nordic nRF8001 BLE chip.
The Blend Micro runs in the BLE peripheral role only, allowing BLE central role devices to establish communication.
Blend Bluetooth with an Arduino Platform - [Link]
One basic need of a computer scientist is to measure the power that a USB device drains off the PC. This device is plugged between the PC and a USB device and displays the current on an LCD. For currents under 100mA it is displayd in 0.5mA steps and 1mA steps for currents over 99.5mA. It is built with an AVR programmed in assembler.
USB Power Monitor - [Link]
This is a little Tetris game. It is built with a Nokia 5110 cellphone LCD and a Texas Instruments MSP430G2553 microcontroller. The system without the backlight uses less than 1mA. It is written in C with the TI Code Composer Studio.
µTetris with MSP430 - [Link]
Prototyping is a useful and powerful method in electronics which lets us analyze a circuit before using it in a system or turning it into a product. In this process we may need a single supply or multiple supplies to power the circuit depending on the type of the application. For example, an op-amp circuit may need a symmetrical supply such as +12V and -12V or a logic circuit may require both 5V and 3.3V at the same time. Some applications may need three or more. This means we should have a bench supply with multiple outputs or multiple bench supplies in the environment. This may not be always possible. This DIY Prototyping Board is designed to provide all the most used supply voltages that a designer will need during prototyping a circuit. The switching power supplies on the board output 3.3V, 5V, 12V and -12V rated at 1A independently. In addition those there are two precise voltage references at 5V and 2.5V provided especially for op-amp based applications.
DIY Prototyping Board with 3.3V, 5V, 12V and -12V Built in Power Supplies - [Link]
by Ashok Bindra:
Whether it is used for biasing avalanche photodiodes (APDs) found in optical receivers, driving photoflash tubes in flash cameras, or charging high-voltage capacitors, the need for high-voltage sources continues to grow. Consequently, in battery-powered units where the input supply voltage is low, step-up or boost DC/DC converters are required to generate voltages that can be several times the input. To address these requirements, suppliers such as Analog Devices, Linear Technology, Maxim Integrated, and Micrel Inc., among others, have produced boost converters with output voltages at 70 V and above.
This article examines such solutions and discusses the topologies and techniques used by each to boost output voltages by ratios of 10:1 or better in order to generate high-DC voltages from very-low DC inputs.
DC/DC Converter Topologies and Techniques to Obtain High Boost Ratios - [Link]
by diyfan.blogspot.gr :
These days I was thinking about a better PIC programmer that can work with Microchip MPLAB IDE software so that I can write my own programs or edit someone else’s programs.
I found that there are numerous versions of the famous Microchip PICkit 2 on the web. Some of them are using the original schematic published by Microchip and some are lite versions – with different parts or simplified schematics. None of them satisfied my requirements. So I got the original schematic, removed the memory chips and the input ICSP connector (which I didn’t plan to use anyway) and made a new single sided PCB. I used mostly SMD parts.
Original PICKIT-2 - [Link]