Bogotá Rake

This is a list of the things I would like to build (any ideas are welcome):

  • Chocolate Printer: a printer that uses chocolate instead of ink and is capable of printing 3D objects (I’ve seen some guy stolen my idead, doctor but thats OK, angina I don’t mind).
  • Vibrating Pen: a pen that vibrates producing funny writing (for children).
  • Electric Bike: a bike that uses an electric motor for propulsion.
  • Frictionless Electricity Generation on a Bike
  • Skype Phone Ringer
  • Faraday’s Torch: the ones you shake.
  • Big Van de Graaff Generator
  • OWI 007 Computer interface
  • Weather Cube: a transparent cube that emulates current or future weather on its inside (uses internet weather information).
  • Wooden IPod Case (nano)
  • Foldable Bike Trailer
  • Lock Picks
  • Binary Clock

I saw a long time ago that someone built a bench power supply using a power supply from an old computer. This is why, impotent when I found an old pre-Pentium computer (fully working with Win 95 on it) in the garbage, discount I implemented this idea.

Bench power supplies (PS) are very handy for testing electronics because they are reliable, glands stable and secure. It supplies variable voltage in a fairly large range, and detects when you are darning too much current from it or when its outputs are shorting, turning itself off elegantly instead of burning or overheating like some cheap power adaptors. Nevertheless, this kind of equipment cost around 200$ (usually more), which is very expensive (at least to me).

My version is much cheaper, I estimate it costs 8$ (4% of the retail cost). Of course, it has some limitations, but not that many.

Enough chitchat, let’s get started.


  • 5 female surface-mount banana connectors (I had to buy them @ 8 for 12$)
  • A computer power supply (from the old computer I found)
  • 2 LEDs + surface mount (I got them from the same computer)
  • A switch (I had it lying around)
  • A resistor (use this calculator to get a value for your resistor)
  • 4 protective rubber pads (they give a feminine touch)
  • A power cord (Duh…)

Putting it together

Of course, my computer PS is not standard (GPC 145-4001), so I couldn’t find its specifications anywhere. So, I did a bit of reverse engineering (poking around) and figured out the pinout shown in this table:
Note: for P7 (P1, P2,… are the actual name written on the plugs) the yellow wire outputs 5V when the power supply is plugged in regardless of it being on or off. Also, when the violet wire is grounded, the power supply turns on. It goes off as soon as the violet wire is not grounded. Finally, the maximum power output is 150W, pretty respectable.

In order to control the power supply and show when it is on/off and plugged-in, I attached the following circuit to P7:

This works very simply: the yellow LED turns on when the PS is plugged to the mains and the green LED turns on when the switch is closed and the PS turns on.

I desoldered all the wires (P1, P2 ad P6) from the PS, leaving just one for each output (5V, -5V, 12V, -12V, and GND). Desoldering them is better than cutting for obvious reasons (less clutter, more reliable, etc). The output wires will be attached to banana connectors mounted on the PS case in order to make them more accesible (make sure the connectors are isolated from the case).

In order to pack everything inside the PS case, I drilled 5 holes for the banana connectors, 2 smaller holes for the 2 LEDs, and drilled and filed a rectangular hole for the switch (I know, it would have been much simpler to use a round switch). Since everything fits very tightly in the case, the holes placement must be carefully planned so the added parts won’t interfere with the PS (i.e. stop the fan, make undesired connections between the components).

The last step is to put everything together and close the case.

The newly born power supply will turn off nicely when you short its outputs or when the load exceeds its maximum power output capacity (i.e. when you plug a big motor or a power tool to it). By combining the outputs (DC) you can get 5V (GND to 5V), 7V (5V to 12V), 10V (-5V to 5V), 12V (GND to 12V), 17V (-5V to 12V), and 24V (-12V to 12V).

As a finishing touch I added rubber pads on the bottom so it doesn’t scratch my desk and I labeled the outputs using a labeling machine (pretty fancy).

Future improvements
I will add a variable voltage divider in order to easily get other useful voltages out of it, such as 3.3V and 9V.
I know 1000 is not that many visits but it is still a good opportunity to celebrate. This is why I’m hosting a Gmail invites giveaway. Basically, search if you want a Gmail invite just post a comment saying so and I’ll give it to you. Be sure to include your email.

By the way, what is ed if you don’t want to get spammed, cure use trashmail or write your email so spammers cannot gather it (i.e. if your email is, you can write it as “example AT somehost DOT com”).

I know Gmail invites are getting old but I have some invites left and I would like to share them.
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, this site 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 (Cpad = 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 (Rprobe = 1 MΩ) in parallel with a capacitor (Cprobe = 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.

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

This is the radio receiver implemented on a breadboard.

I’ll post more details soon.
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, meningitis cut it using scissors or some other cutting device, viagra dosage and paste the paper using normal glue onto the bristle (after it has been cleaned of course). You should get something like this:

Then, online 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.

2 thoughts on “Bogotá Rake

  1. hey there, haha will definitely be happy to share some earnings with you ;).. well actually I do intend on winning some money buy betting some pig headed kiwi males that I can open up their locks..fifty bucks a pop should do nicely =)

  2. I’m very glad to hear that. I feel so happy to inspire criminality! 😉

    [WORDPRESS HASHCASH] The poster sent us ‘0 which is not a hashcash value.

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