Making a relay board! (Part 2 of switchboard project)

The first thing that was necessary for any electronically controlled switching setup was going to be the relay board. The board I ended up making used 6 volt relays supplied with ~6.6 volts which was being rectified by an on-board rectification setup.

The rectifier used a 6-0-6 center tapped transformer with a simple 2 diode rectification setup and a large 470 micro-farad filtering capacitor which is providing a constant 6.6-6.8 volts DC on the output. Which is just about enough for an LM-7805 to regulate at 4.9 volts which is pretty OK for powering our micro controller and digital circuitry since I'm not using anything too voltage sensitive.

In order to control the relays using the digital circuitry, I've used an array of 2n2222 transistors which connect to a simple SIL connector which allows the board to be connected to and controlled by the digital board.

The diodes which are connected in reverse direction with the relays are called 'Free wheeling diodes' and allow current stored in the primary coils of the relays to safely dissipate without harming the transistors or other components.

I fabricated the board on a simple double sided PCB and connected the AC mains and relay outputs to a header block. The PCB was printed using the toner-transfer method and etched using Ferric chloride enchant. The end result wasn't too bad if I do say so myself.

The board

The Relays and diodes (missing one because I ran out!)

The rectifier and resistors.
(Missing the connector because I hadn't bought it yet)

A remote controlled switch board?

A little thought that crossed my mind when I had to get up to adjust the fan speed for the 5th time, I should make something that would allow me to change the fan speed and do stuff like turn the lights on and off by using an IR remote control.

A bit of googling later, I found tons of commercially available switchboards which are pretty much plug and run.

But what's the fun in that?