292 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:


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 [...]