294 articles written by T.K. Hareendran

Author: T.K. Hareendran

About: Internationally Certified Freelance Technical Author/Circuit Designer Electronics Engineering Technologist Founder & Promoter of TechNode» PROTOLABZ – An Open Source Hardware R&D Lab Tel: +91 (0) 9447712139 Email:


Building a Smart Master/Slave Switch

T.K. Hareendran - 12/06/2017

Here is an inexpensive and easy-to-build master/slave switch for integration into powerstrips for the automatic switching of “slaves” [...]

Wi-Fi Witty Primer

T.K. Hareendran - 11/28/2017

This is just an introduction to Wi-Fi Witty (also known as Wi-Fi Witty Cloud Development Board/ESP Witty) — [...]

Visualizing Data with Arduino

T.K. Hareendran - 11/14/2017

I like to visualize things, so I decided to prepare this simple tutorial to help you better understand [...]

How to Use Switch Mode Power Supplies to Power Your IoT Design

T.K. Hareendran - 11/07/2017

An effective and long-lasting power supply is the backbone of any IoT device. Switch-mode power supplies (SMPSs) are [...]

USB Power Testing With an Arduino Controlled Dummy Load Project

T.K. Hareendran - 11/01/2017

One part that I find myself using somewhat regularly in microcontroller-based experiments is the “USB power bank” that [...]

Getting Started with BLE and Arduino

T.K. Hareendran - 10/24/2017

The MLT-BT05 is a readily available, inexpensive Bluetooth 4.0 module based on the Texas Instruments CC2541 Bluetooth Low [...]

Having Fun Building a Remote RC Firecracker and Firework Igniter

T.K. Hareendran - 10/16/2017

A recent discussion with my friendly editor, Adam Carlson, rekindled my idea of designing an unusually simple, yet [...]

ESP32 — Getting Started the Easy Way!

T.K. Hareendran - 10/03/2017

  Open-hardware platforms enable rapid prototyping and faster time-to-market of new IoT applications. The objective of this post [...]

Open-Source Light Meter

T.K. Hareendran - 09/20/2017

Light meters, these days, are no longer a mystery: From home-improvement stores to eBay and Amazon you can [...]

Build Your Own Smart Bike Battery Gauge

T.K. Hareendran - 09/14/2017

So you’d kind of like to know when the battery in your bike is getting a bit flat, [...]