Use a transistor as a heating element


REC Johnson, B Lora Narayana, and Devender Sundi share their design idea on how to use a transistor as a heating element.

It is common to use transistors for driving resistive heating elements. However, you can use the heat that a power transistor dissipates to advantage in several situations, eliminating the need for a separate heating element because most transistors can safely operate at temperatures as high as 100°C. A typical example is in a biological laboratory, in which the need for maintaining the temperature of samples in microliter-sized cuvettes is a common requirement. The space/geometry constraint and the less-than-100°C upper-temperature limit are the basic factors of the idea.

Use a transistor as a heating element – [Link]

Exploring Eagle CAD ULPs #3 – Teardrops.ULP Make A Teardrop Shape Connection With Pads and Vias

Welcome to the third post of the “Exploring Eagle CAD ULPs” series. Every week we will publish a new post about one useful ULP in Eagle CAD.

“ULP” User Language Program is a plain text file which is written in a C­-like syntax and can be used to access the EAGLE data structures and to create a wide variety of output files. You can consider it like a plug-in for Eagle.

You can reach the posts published in this series using the following link.


In this post we are going to explore a ULP called ‘Teardrops.ULP’. This ULP makes a teardrop shape connection between the traces and the vias or pads.

Before I found this ULP, I thought that I can’t do the teardrop thing using Eagle CAD, while I saw a lot of designs that have been done using Altium have this feature.

Using teardrop shape connection may result in many advantages:

  1. It prevents drill breakout due to drill misalignment where the trace joins the via or through hole.
  2. It makes stronger connection between the traces and the pads. Thermal expansion when re-soldering/desoldering could sometimes lead to a loose connection where the trace joins the pad.


Image Source - Youtube/Premier EDA Solutions
Image Source – Youtube/Premier EDA Solutions


Image Source - Youtube/Premier EDA Solutions
Image Source – Youtube/Premier EDA Solutions

This ULP should be used with forethought or on a copy of your board file just before plotting because it would be difficult to remove teardrops afterwards. Once added, they can’t be undone using ctrl-z.

Teardrop.ulp GUI
Teardrop.ulp GUI

In the GIF below, I tried to demonstrate how to use this ULP.


Note: You don’t need to download and add this ULP. it’s available in the ulp directory.
To use it, just press the ULP icon from the tool-bar and search for ‘teardrop.ulp’.

Chip-scale atomic clocks bring accuracy and stability to portable applications


Microsemi released a chip scale atomic clock reference bringing stability and accuracy to portable devices.

The Microsemi Quantum™ SA.45s CSAC is the world’s first commercially available chip scale atomic clock, providing the accuracy and stability of atomic clock technology while achieving true breakthroughs in reduced size, weight and power consumption.

The Quantum SA.45s CSAC produces two outputs, a 10MHz square wave and 1PPS, both in a CMOS 0V to 3.3V format. It also accepts a 1PPS input for synchronization and provides an RS-232 interface for monitoring and control.

Chip-scale atomic clocks bring accuracy and stability to portable applications – [Link]

WaRP7 – A New Platform For IOT And Wearable Technology Applications

“WaRP7” is a new platform which increases developer’s opportunity to innovate and bring new products to the market by smoothing and speed up the development process of IoT applications and wearable technologies.


WaRP7 is a $85 platform designed by “Farnell element14”. It consists of a main board and a daughter card. The main board comes with a i.MX 7Solo applications processor from NXP and 8GB storage memory. WaRP7 supports WiFi, Bluetooth, USB-OTG, BLE, and NFC connections.

The processor is a member of i.MX 7Solo processors family and it is designed for devices that require high-performance processing with low-power requirements and a high degree of functional integration. It features an advanced implementation of the ARM® Cortex®-A7 core, as well as the ARM® Cortex®-M4 core.

Using the daughter card ‘WaRP7 IO Board’, prototyping will be fast thanks to the ability of using various expansion modules. It has a flexible design connected with various sensors to collect data, and a MikroBus™ expansion socket which opens users to over 200 Click Boards™ from MikroElektronika.

WaRP7 features the following sensors, located in the daughter card :

  • A high-precision barometer.
  • A six-axis sensor combining an industry-leading accelerometer and magnetometer.
  • A three- axis gyroscope.

Another key element provided in the WaRP7 platform is a MIPI CSI Camera.


WaRP7 Architecture
WaRP7 Architecture

About the OS of WaRP7, both Linux and Android can work on it based on NXP-standard BSPs without modifications.

WaRP7 is an open source platform, the source files including the PCB design files are available Here.

Farnell element14 tries to provide  a solution for most challenges faced in IoT and wearables market with the WaRP7 platform, such as battery life, connectivity, user experience. Some examples of its applications are: smart homes, smart cities, smart appliances, activity tracker, smart health, smart clothing and more.


WaRP7 development kit is available for about 85$ and contains WaRP7 CPU board ƒ, WaRP7 IO board and Lithium-Polymer battery.

Read this factsheet for more information.

Via: Element14

ESP8266 Wifi enabled 8×64 pixel LED matrix display


Raj @ build an ESP8266 based led matrix display. This matrix is a modification of his previous bluetooth version and uses an ESP8266 as a web server to setup the display message. No other microcontroller is used to control the display so things are kept simple and easy to build your own.

This project is a modification of my previous Bluetooth-enabled LED matrix display project, which used 8×64 monochromatic LED matrix (total 512 LEDs) for displaying scrolling text message. The original project used Bluetooth for display data transfer from a smartphone, but this one now uses Wifi. The display message is sent through web browser to a ESP8266 module that is configured as a web-server. No Arduino or any other microcontroller is used. ESP8266 alone works as a WiFi server and drives the MAX7219-based LED matrices.

ESP8266 Wifi enabled 8×64 pixel LED matrix display – [Link]

A very simple DIY solar-powered USB charger


Raj @ tipped us with his latest project. It’s a simple, but useful USB Solar powered charger able to charge a power bank or your smartphone.

Yesterday, I built a very simple DIY solar-powered USB charger for my TP-link 10400mAh USB Power Bank. All I needed was a 6V/3.5W solar panel and the TD1410-based 5V buck converter module. I bought both of them on Aliexpress for less than $8.

A very simple DIY solar-powered USB charger – [Link]

Air pressure sensors in smartphones


Dr. Thomas Block has a great article about air pressure measurement on smartphones and which benefits this may have.

Today’s smartphones utilize a wide array of accelerometers, gyroscopes and various other sensors in their designs. Relatively unknown is the barometric pressure sensor, which measures air pressure. These sensors are currently being integrated into premium-grade smartphones, but are also becoming more common in mainstream phones or wearables such as fitness trackers and Internet of Things (IoT) applications.

Air pressure sensors in smartphones – [Link]

Basic Electronics – How to use a 555 Timer

Do you want to know how to use a 555 timer? Laura brings you more Back to School tips and tricks on using this integrated circuit.

Basic Electronics – How to use a 555 Timer – [Link]

Circuit provides cold-junction compensation


Mark Maddox @ has a design idea on cold-junction compensation using AD7708.

The accuracy of any circuit or system that uses a thermocouple to determine the temperature of a process is limited by the accuracy of the method used to perform cold-junction compensation. In a thermocouple measurement, two wires of dissimilar metal join together at the “hot,” or measurement, junction. The isothermal termination of the thermocouple wires provides a second “cold,” or reference, junction. The potential across the thermocouple is proportional to the temperature difference between the two junctions.

Circuit provides cold-junction compensation – [Link]

100Vin, 5W out regulator uses primary-side control


LT8303 is a monolithic flyback regulator in a TSOT-23 package that simplifies the design of isolated DC/DC converters. By sampling the isolated output voltage directly from the primary-side flyback waveform, the part requires no opto-isolator, LT1431 or third winding for regulation. by Graham Prophet @

The LT8303 operates over a 5.5V to 100V input voltage range, has a 0.45A/150V integrated DMOS power switch and delivers up to 5W, suiting it for a range of telecom, datacom, automotive, industrial, medical and military applications. The output voltage is set with one external resistor and the transformer turns ratio. Several off-the-shelf transformers are identified in the data sheet. The LT8303 operates in boundary mode, which is a variable frequency current mode control switching scheme, typically resulting in ±5% output voltage regulation over the full line, load and temperature range. Boundary mode enables the use of a smaller transformer compared to equivalent continuous conduction mode designs. The high level of integration and the use of low ripple Burst Mode operation result in a simple to use, low component count and high efficiency application solution for isolated power delivery.

100Vin, 5W out regulator uses primary-side control – [Link]