Solenoid Valve

I got a cheap Chinese made 1/2" 12-24V solenoid valve from eBay for around ₹400, for automating a drip irrigation system. Going by the specs it appears to be the same valve popular among Arduino hobbyists, sold on SparkFun and AdaFruit. Made of plastic, but works well. Note that the valve does get hot in... Continue Reading →


Drip Irrigation

For ₹1800 you can build a drip irrigation system using PVC pipes in less than day, which can water 5 rows of 9 plants each. This is for a garden bed of size 10' x 10' (3m x 3m). Overview Making the system turned out to be simpler than I thought. It took me no more... Continue Reading →

Balar Illam – SSTC

Few weeks back I thought I'd put the SSTC (see Tesla Coil - SSTC) to good use to inspire kids at the local Balar Illam (orphanage/hostel for kids). No end to their curiosity and questioning. Thought I'd be done in 1/2 hr, but each session went on for almost 2 hrs. Starting with what is... Continue Reading →

Tesla Coil – SSTC

Introduction This is based on the very popular and ingeniously simple SSTC known as the Slayer Excitor by Gary Bluer. My SSTC project started off as a mini SSTC demo for school kids. Below are the specs for a mini, medium, and large coil. They generate arcs roughly 1cm/2cm/4cm and draw around 0.8/1.2/1.8A @ 32V.... Continue Reading →

Restoring Pride

Any chance I get, I talk about Hindu contributions that changed the world, starting with mathematics, like: The Zero - first formal description by Hindu mathematician Bhaskara, and first use by Hindu astronomer Brahmagupta to represent things in colossal scales. This is a very profound concept, that could have been only conceived from people who... Continue Reading →

Induction Stove Repair

Took apart an induction stove that stopped working. First thing noticeable was that the internal 10A fuse was blown. When I plugged it in with a new fuse, not only the fuse blew, but something exploded on the circuit board right underneath the heatsink, spitting sparks, a burst of yellow flame, followed by a jet... Continue Reading →

Fan Repair

This post is for anyone else trying to determine how the four wires (common, low, medium, high) of an A/C induction motor of a pedestal fan are connected to the windings. I happened to have one pedestal fan with a bad motor (Orient fan) and another fan pedestal fan with bad controller circuit (Usha fan).... Continue Reading →

Raspberry Pi CCTV

After my dad passed away last year, I needed to keep an eye on mom, who's living alone in our native home in India. So in this trip, I set up a remote CCTV for my native home using two Raspberry Pi's. This post is a note of all the steps for anyone else trying... Continue Reading →

Engineering Ethics

"Lund's first response was to repeat his objections. But then Mason said something that made him think again. Mason asked him to think like a manager rather than an engineer." That fatal decision resulted in the Challenger Disaster that cost the lives of all 7 crew members. Was it because Lund was thinking like a... Continue Reading →

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