Gigaset A490

Cordless phone wasn't working, it would turn itself off within 3min. Opening the phone (Gigaset A490), did not see any noticeable loose connections or shorts. Only damage is that the paper from the speaker cone had been eaten away leaving lots of black powdery residue all over the phone. Just cleaning the PCB with rubbing... Continue Reading →


Drip Irrigation – Algae

Within a span of 2 months, algae started appearing in the inlet and outlet tubes. As expected, following nature's law of exponential growth, within the next 2-3 months it filled the whole tube, pretty much clogging the solenoid valve inlet and outlet. I'm guessing the exposure to sunlight from the transparent tubes is causing the... Continue Reading →

Drip Irrigation Automation

Automated the watering of Drip Irrigation by using a solenoid valve controlled by an Arduino board. Note that while I played around with a soil moisture sensor, which works fine in the lab, but I decided not to use it in the field for the following reasons: Corrosion of sensor electrodes due to salty water.... Continue Reading →

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 →

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