Gadget design, robotics, hacks, DIY technology and more.

A Bogotá (besides being a city) is a very effective lock picking tool. It is surprisingly easy to build and allows you to open lots of locks very quickly and easily. I have been able to open many locks just minutes after having this little tool done (including standard door and bicycle locks).

For this project you only need one street sweeper bristle. You can find these on the streets after a street sweeper passed by. Their rotating brushes leave behind these precious bristles.

First you need a template. I found this very good one from Exodus5000.
You have to print it at its original size (@ 500 pixels/inch) onto a piece of paper, cut it using scissors or some other cutting device, and paste the paper using normal glue onto the bristle (after it has been cleaned of course). You should get something like this:

Then, using a permanent marker paint around it and remove the paper.

Now, use some files to remove all the painted sections until you get the desired shape.

Sand it very thoroughly. It is very important. First use a medium grain sandpaper and the a fine one. In order to sand all the curvy sections, I used a piece of sandpaper rolled around a medium nail. In the end, it should be smooth as ….hum… as something very very smooth. This allows for a fluid motion of the Bogotá inside the lock (important if you want to get the lock open).

I accidentally broke my bristle. With the broken piece I built a tension wrench. it is a bit short, but it works well. If you want one, just bend the bristle (not to much or you may snap it)

For those who don’t already know, a tension wrench is used to apply a small tension to the lock while you pick it. See this article for more information.

With these tools you can now start a life of crime. You should be able to open simple locks (and perhaps more complex ones) in a couple of minutes. Simply apply a small tension to the lock (as if turning it with a key) using the tension wrench, and jiggle the Bogotá inside the lock rapidly and randomly. The lock should open in less than a minute (keep trying if it doesn’t).

Disclaimer: I do not condone leading a criminal life. However, if my blog does inspire you to become some sort of criminal and you succeed well at it, please share a bit of your earnings with me. After all, you will be doing well thanks to me.

This is the schematics for a wireless AM receiver composed of a tuned amplifier, a AM demodulator, and an audio amplifier.

This is the radio receiver implemented on a breadboard.

I’ll post more details soon.

My teammate and I designed an integrated op amp. The circuit is implemented using Gennum GA911 technology. It is built so we can test many configuration (i.e. using active or passive biasing). Se below the circuit layout and some pictures of the resulting chip in it’s natural environment.

Active-loaded differential amplifier. This is the first Stage of the op amp, with a 5o dB Gain.

Class-AB output stage. This second stage alows for driving small loads and increases the overall gain a bit (~10 V/V).

Note: all circuit schematics account for the pin capacitance of the packaged IC (C_pad = 5 pF). Also the loading effect of the oscilloscope probe used to perform the experimental measurements is accounted for in the schematics by modeling the probe as a resistor (R_probe = 1 MΩ) in parallel with a capacitor (C_probe = 15 pF).

IC layout (done using Electric).

The chip (a.k.a. #5) being tested.

The chip in its natural environment.

A close up on the naked chip. Pretty neat.

I’ll post more details soon.