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22 Feb 2014


EMI mains filters Schurter combined with an input AC connector will stop interference there, where it´s the most efficient – at the input.

To be more precise, usually it´s the best to eliminate interference (EMI) already at a source of interference itself. But because there are a lot of disturbance sources in a common 230V mains, the only reliable possibility how to protect our device is to equip it with a suitable filter. Another positive thing is also a prevention of possible transfer of noise from our device into a public network (mains).

Reasons why to use a filter or other EMI suppressing components are well known. In general here belongs a protection of circuits from unwanted influence (digital and analogue circuits), as well as protection from damage to a device in an urgent case. EMI is in general a “silent killer”, as it appears with a various intensity and often absolutely irregularly.

Those ones, who´ve already experienced searching for a fault, why a given device works irregularly, can say realistically about problems, which EMI is able to cause. It´s treacherous to think, that there´s no interference in a given place, because even if we´ve really measured only a small interference, it can appear anytime without warning.

Interference in mains can be described in four categories:

  • fluctuations (voltage) in an industrial network
  • harmonic interference in a range of 100Hz to 2 kHz
  • transient interference in a range up to 300 MHz
  • sinusoidal high frequency interference up to 1GHz (or even more)

In practice, interference appears mainly in last three categories. Filters are usually constructed from capacitors and inductors, or also some other components like varistors, transils, VHF chokes etc. Wide band filters are often composed of 2-3 stages. Capacitors connected between L-N are marked as „X“ and capacitors between L-PE and N-PE as „Y“ capacitors. Leakage current of a filter is mainly determined by „Y” capacitors. As medical devices must meet more stringent requirements for a leakage current, in most cases they don´t use „Y“ capacitors (even for the price of somewhat lower EMI suppression).

EMI filters are available in various versions and they use to be the most effective if they are directly on the device input. Swiss company Schurter as a specialist in a given segment offers a wide range of filters combined with an AC inlet socket or also with a switch and fuses. An advantage is that by using such a module, you´ll manage four components by one component and also their mechanical assembly to a panel. In our stable stock offer can be found several filters. Many details about a construction of Schurter filters will provide you the following document.

Say stop to unwanted “visitors” - [Link]

22 Feb 2014


miniLOG is a precise standalone voltage logger that save the data on a SD card. It has 4 basic analog channels:

  •  one has 12bit resolution for voltage measurements,
  • two channels have 10bit resolution for voltage measurements and
  • one channel has 10 bit resolution for current measurements.

Input voltage range is 0-25V and current range is 0-500mA. The data are written on a simple .txt file on SD card and can be further proccessed using spreadsheet software.

miniLOG – Precision Standalone Voltage Logger - [Link]

21 Feb 2014


Inductive Loop Detector is detecting the inductance change of a buried wire coil and thus it can be used to detect metal objects. by elektronika.ba:

Inductive Loop Detector works by detecting an inductance change in wire loop (coil) that is buried in road. It does that by measuring the frequency of the internal oscillator which powers the mentioned coil. When a metallic object moves over the coil it changes its inductance and that in turn changes the oscillator frequency which is measured by the microcontroller.

It is used for vehicle access control at door and barrier controls, for monitoring the occupancy and for vehicle counting in parking garages, traffic light installations and traffic controllers, direction and speed detection of vehicle traffic (if dual channel version is used), in car-wash plants, etc.

Inductive Loop Detector - [Link]

21 Feb 2014

This is a walk-through for making cheap high quality SMD metal stencils at home, using commonly available materials.

DIY home-made SMT metal stencil - [Link]

21 Feb 2014

Reflow soldering of resistors, capacitors, diodes, controller, and other surface mounted components using a hot air gun. This is a prototype PCB of a custom designed mechanical keyboard, GH60.

SMD soldering by hot air - [Link]

20 Feb 2014


There is a new 8mm RGB LED introduced to the WS2812 family of LEDs. cpldcpu writes:

There is a new addition to the popular WS2812 family of RGB LEDs with integrated controller: A 8mm through hole version. Right now they seem to be in pilot production stage. The only place that has them is Soldering Sunday where they are called PixelBits. My understanding is that they will also be available at the usual sources later this year. I got a couple of them to test for compatibility with my light_ws2812 library.

New member of the WS2812 RGB LED family - [Link]

20 Feb 2014


This project is a simple LED tester and LED polarity checker. It can be used to check 1206, 0805, 0603 and 5mm LEDs. All parts are readily available and they are very cheap. Usage is very simple. Just press the tack switch to first check the battery is good. The blue led will turn on. Now you are ready to test your leds and check their polarity.

Simple SMD LED tester - [Link]

20 Feb 2014


This project is a 7 segment LED display module that can be driven using SPI protocol, so it needs only 3 pins of your mcu to drive 4 x LED displays. It’s based on MAX7219 LED display driver.

Seven segment LED displays are very popular for displaying numeric information because they are very attractive and readable from a far distance and wider viewing angle.

The downside is they are resource-hungry. For example, it requires 12 I/O pins of a MCU to drive a 4-digit seven segment display using a standard time-division multiplexing technique.

Here I present a serial seven segment LED display module that can be used with any MCU using a 3-wire SPI interface. This particular display has four digits (0.40” size) and two colon segments (to support time display) display.

Serial 4-digit seven segment LED display - [Link]

20 Feb 2014


Check out the world’s first open-source Bitcoin ATM:

Open Bitcoin ATM is the worlds first open-source automated teller machine for education and experimentation.
Want to make one? Here’s a step by step tutorial. It takes about 7 – 10 hours to build with simple tools. Cost of components are less than $500 new but used parts can be purchased for even less on eBay.


Open Bitcoin ATM - [Link]

20 Feb 2014

A single-chip catheter-based device that would provide forward-looking, real-time, three-dimensional imaging from inside the heart, coronary arteries and peripheral blood vessels is shown being tested. (Click image for high-resolution version. Credit: Rob Felt)

Researchers have developed the technology for a catheter-based device that would provide forward-looking, real-time, three-dimensional imaging from inside the heart, coronary arteries and peripheral blood vessels. With its volumetric imaging, the new device could better guide surgeons working in the heart, and potentially allow more of patients’ clogged arteries to be cleared without major surgery.

The device integrates ultrasound transducers with processing electronics on a single 1.4 millimeter silicon chip. On-chip processing of signals allows data from more than a hundred elements on the device to be transmitted using just 13 tiny cables, permitting it to easily travel through circuitous blood vessels. The forward-looking images produced by the device would provide significantly more information than existing cross-sectional ultrasound.

Single Chip Device to Provide Real-Time 3-D Images from Inside the Heart and Blood Vessels - [Link]





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