For my Home automation over Ethernet project I’m using an AVR micro controller. Several companies offer in system programmers for these controllers. Since I don’t need in system debugging a simple programmer will be enough form me.

The programming cable is a printer port cable (parallel, LPT) with some resistors to protect the port. I don’t use optical isolation, it’s a direct connection. This brings some risks but is cheap, very cheap.

To make the programmer I used an printer old cable, and soldered resistors on the end as follows:

All resistors are 220R. This cheap AVR programmer works great. To send the programs to the AVR’s memory I use Ponyprog, a free tool compatible with the programming cable.

A lot of houses are equipped with a wired Ethernet LAN. So why install an extra network just to turn on and of a light bulb or dim a light? Wouldn’t it be possible to use an ordinary Ethernet connection to control our home appliances?

On my job I use ‘Industrial Ethernet’ everyday. It’s like your home LAN, but with more expensive switches and, in general, green wires and fancy connectors. The principles are the same, but for security reasons it’s separated from the office LAN. For home automation purposes it’s not necessary to separate the networks, actually it’s better to have only one network. That way I’ll be able to control the appliances from my computer.

My user requirements:

• Create a micro controller based module that ’speaks’ Ethernet.
• Make expansion modules to add relays, dimmers and inputs to the CPU.
• A user interface (VB.net and/or web based) to control the modules
• A computer service handling the logics (for time based switching etc.)
• …

To create the CPU module I’ll use a webserver board from http://tuxgraphics.org/, when the basics are programmed I’ll go on developping the hardware.

As enclosure for the modules I will use DIN-rail housings. This will not be the first concern, but size WILL matter while developping the printed circuit boards.

Things to do:

• Find the right programming and development tools
• Design PCB’s (probably with EAGLE)
• Make the PCB’s

The first two points on the short time to-do list are clear. The last one, the production of the circuit board, I’m not yet sure about. I never made a circuit board before. Will I use my CNC router do isolate the paths, make a UV box and use boards with a light sensitive layer or just find a company to produce the boards? I don’t know yet, suggestions are appreciated…

There are several reasons to extend a VGA cable. A Media Center PC is a great tool to manage your music, movies, pictures etc. To avoid a noisy computer blowing in your ears while watching a movie a VGA extension cable could be a great help. Mounting your home theatre beamer on the ceiling is a good idea, but how to get there with the VGA signal? Extend it using cheap cat5 UTP cable!

Connect the cables as listed in the following table. Wire both connectors the same way.

The only drawback is the slightly notable ‘ghosting’ as a result of the difference in impedance with a regular VGA cable. With the extension I use (12m) the ghosting is only visible when showing black text on a whte background. But since the beamer is only used to watch movies, television and pictures I never had complaints about the quality. If you really want to improve the quality, an STP cable could be the solution.

Techible.net engraved with CNC router

Ever wanted to cut some wood with very, I mean VERY high precision?  Or just want to do some cool engraving? I have what you need. A home made CNC (Computer Numeric Controlled) router.
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The energy prices are raising higher than ever before. The most effective way to heat a swimming pool is probably a solar collector or a heat pump. But if you have a huge stock of firewood like me, a fire-based heating installation is an option to consider.

The principle is simple: a heat exchanger in the chimney of a garden stove. The heat of the fire and the gasses are used to heat the water. Also making the heat exchanger itself is not complex or difficult to achieve. A flexible copper tube is turned into a spiral and at the ends equipped with connections for a garden hose.
In the swimming pool finally I placed a pump with a low flow rate I had laying around.

An initial test was done with a small bath. The temperature of the water raised soon to a temperature that was no longer tolerable to the bare hand. The bath had a capacity of about 80 litres.
This is obviously nothing compared to the pool for which the heating will be used, an Intex pool with a capacity of 12 cubic meters.