Wednesday, December 19, 2012

Solid State Relay Switched Mains Rig

Introduction


For a number of my upcoming projects I need a rig to test the functionality of a solid state relay that would be driven by a microcontroller and switch the mains for other devices. Having done projects with similar requirements in the past I remembered how much pain it was to test the solid state relay (SSR) with naked mains cables running around, etc. This time I decided to create a marginally more sophisticated setup that would allow a quick, easy and safe way to do this. Also, now that I have made this once, I can reuse this rig in any future project with zero effort. Making this took about a day's work - most of the time was spent on finding materials that suited my needs.

This mains output is switched by a solid state relay, baby! :)

Monday, December 3, 2012

Programmable Timer Switch

Finished unit mounted on the wall, in use.

Introduction

This project, like others before, has started out of need: our 30+ year old mechanical timer for the central heater of the house has finally given it up. It would have been faster and cheaper to get a replacement from the local hardware store, but I decided to learn something new and I set out to create a digital version of it.

I wanted to create something simple, something that anybody can use without any experience in electronics - i.e. not a geeky device that could only be used by me, but something that anyone living in the building could set up properly, given a User's manual.

I did a quick research asking people in the building (mostly relatives) about what functions they would like to see in the new timer. As much as I wanted to cram as many features in the device as I possibly could I had to leave most of my ideas for another project - the consensus was to be able to set up periods of time (from now on: time slots) within a day when the heating is on. Period.

However, with some modifications in the firmware new features, like time slots set up for any day of the week or month, could be easily added.

With minor modifications of the hardware this could be extended to several channels, i.e. more than one "item" could be programmed to be switched on/off in a given time slot.

This timer is currently used as a timer switch for the central heating of the house, but it can switch pretty much anything you attach to it. I will still refer to the output as heater for the rest of the article.

As usual, this project is available as kits or fully built units - for details, please drop me a line.