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Sunday, October 5, 2008

Carjacking - shortening the path for justice

As automobiles become more sophisticated, direct theft by tampering with the ignition system becomes a nearly impossible task. This narrows down the choices left for the criminals, who end up adopting the only choice where successful access to the vehicle is guaranteed: threatening the occupant(s) with a weapon in exchange for the car.

In general the criminals can get away with this type of crime if they are efficient and careful, leaving the victim with few evidence to help in the investigation and tracking of the vehicle.

However, once again we can put technology on our side, and in an attempt to be resourceful enough, take advantage of two broadly available devices: a cell phone and a GPS module. These devices
are becoming cheap enough to have dedicated in a discrete location inside the car for a single purpose: on demand location.

By being able to query the location of the car just by sending an SMS message to it and get a reply with the corresponding GPS coordinates, this could be a useful tool in the police work, as real time location would always be possible.

Following this idea, I've decided to attempt a simple implementation of one such system which I have designated "Vechicle Finder". Having as a platform a Nokia smartphone and a Bluetooth GPS device (both sitting on a board for convenient fixation of the apparatus), I have developed a Java application which reads the GPS coordinates and sends it as an SMS to the originator of the request SMS:



Upon receiving an SMS containing a special command and some optional parameters, this onboard device will reply with another SMS containing the following data:

Sunday, September 7, 2008

The meanders of OBD-II protocols



As we travel through the history of automotive technology back and forth, we realize that at the heart of the machines that enable us to go from point A to point B faster than our legs, are a number of components that essentially haven't changed too much: engines still burn fossil fuels and the vast majority are based on pistons that transform the explosive energy of the fuel combustion into movement.

Saturday, March 22, 2008

Saturday, March 15, 2008

Long-haul WiFi - new developments

Returning to the WiFi topic, here is the new antenna development that I had promissed in the early post, once the dual "cantenna" design was finished.

The dual cantenna is quite efficient, as I realized by connecting it to reasonably distant access points (in excess of 200 meters, with many obstacles between, including houses). By verifying the antenna efficiency was the expected, I assumed that in better conditions the range could be far greater, by establishing a link between two antennas of this type or other type of optimal configurations.

However, I knew I could push it a little further, so I decided to buy a 12 euro 45 cm dish from a regular satellite TV system, and the materials to build a biquad feed. I installed the dish on top of the tripod used for the cantennas, and attached the biquad feed (built according to these instructions) to it:



Monday, January 7, 2008

Water Fuel Cell - DC voltage results

Today I performed some tests measuring gas production with DC voltage. The tests were performed in order to obtain aproximately the same consumed power, namely 22 Watts.

DC test performed:


High frequency test (100 KHz) at same voltage:


The DC test shows a clear increase in efficiency (almost 25%) relative to the pulsed electrolysis.
Still to compare these results with low pulse frequencies (it is likely that power losses are quite high at 100 KHz).

Sunday, January 6, 2008

Water Fuel Cell - more results

For one measurement taken without the inductor coil, we have the following values:

Friday, January 4, 2008

Water Fuel Cell - measured results

I performed two consecutive runs without changing the conditions. The data obtained is as follows:

Considering that it consistently took 4 minutes to produce 80 ml of H2 + O2, this
gives a rate of 1.2 litres/hour of H2 + O2.

Water Fuel Cell - back to business

After reparing the WFC and adding extra safety measures, here is the entire setup producing hydrogen at 12 Volts DC and 1.94 Amps. Next I will provide a grid with measured values, including gas volume:


Thursday, January 3, 2008

Water Fuel Cell - cleaning the mess and repairing the electrolyser

After yesterday's mishap, and of realizing how lucky I was to still be in one piece, it is time to take a deep breath and after looking into what went wrong, follow all the safety measures to prevent one such event from ever happening again.

I started by getting a new lid for the electrolyser and putting a new seal rubber in it, this time with two clamps instead of one. Now only the clamps are used for holding the lid. The original ring around the lid was discarded. By itself this doesn't provide extra protection against an explosion, apart from the slight probability of the lid popping out in one piece instead of fragmenting into several pieces (today I still found fragments of the lid in distant corners of the room).

Wednesday, January 2, 2008

Water Fuel Cell - HUGE ELECTROLYSER EXPLOSION

Sometimes mistakes can be the death of the artist. In this case I got closer to it than desirable: after building a tiny bubbler for testing sustained combustion I hooked it up to the electrolyser (aka: Water Fuel Cell) - one tube going from the electrolyser to the bubbler and another tube from the bubbler to the gas exit, where combustion would be tested.

The bubbler was working fine, air tight as necessary. After approaching the output from a flame, small explosions along the tube would occur, without affecting the WFC.

Tuesday, January 1, 2008

Water Fuel Cell - inductive load added

Just as refered by several people doing this type of research, adding and inductive element to the load would create a resonant LC circuit, with the WFC as a capacitor. I used as an inductive load the secondary coil from a 220 V / 12 V transformer which was added in series with the WFC. The most notable effect was the suppression of the high frequency signals at the WFC, along with a voltage dropout of nearly 5 volts. The curious thing however is the fact that the gas production doesn't seem to be affected for the same input voltage/current conditions. As the transformer becomes hot after a couple of minutes of operation, this shows that there is less energy going to the WFC.

This sample video shows the cell in operation under these conditions: