297 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:


12V Car Battery Monitor

T.K. Hareendran - 08/05/2010

Here is an interesting Car Battery Monitor circuit of a low power electronic dc voltmeter circuit that can [...]

Flame Failure Monitor

T.K. Hareendran -

A minimum amount of hardware is needed to build a simple flame or fire failure monitor that enables [...]
12 volts car adapter diagram

Safe 12V Car Adapter Circuit

T.K. Hareendran - 08/03/2010

Safe 12V car adapter described here can be used to limit a +12 volt car battery current, available [...]
led torch diagram

Astro LED Torch Circuit

T.K. Hareendran - 04/06/2010

A red LED torch is essential for preserving your dark adapted vision at night allowing you to read [...]
timer light switch circuit diagram

Timer light switch circuit

T.K. Hareendran - 04/01/2010

Tiny Timer Light Switch presented here is a simple transistorised electronic timer which drives a high efficiency white [...]
smoke sensor alarm circuit diagram

Smart Smoke Alarm Circuit

T.K. Hareendran - 03/30/2010

At the heart of this ultra simple smoke alarm is H21A1, which is a photo-interrupter module consists of [...]

Improved Infrared Detector Circuit

T.K. Hareendran - 03/27/2010

This improved infrared detector is specifically intended for use with commercial IR remote control handsets. This little circuit [...]