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December 31, 2008

Breadboard Bench

I found a nice breadboard in McGill's garbage a while ago and decided to convert it into an electronics bench. My main goal was to have a powerful power supply with regulated outputs combined with a breadboard and some useful connectors so I can build circuit prototypes easily. Also, I needed a new bench power supply since mine was lost in the Lunar Excavator shipment.

  • A nice breadboard found in the garbage
  • A computer power supply
  • An ATX motherboard power connector
  • Two LEDs with resistors for current limiting
  • A switch
  • Some cables

Putting it Together

I wanted to build a modular system so I can replace the pieces easily, especially the power supply (since it comes from an old computer and may not work for very long).

I connected a switch and two LEDs (actually, my switch comes with an integrated light so I used only one LED) to the PS ON, 5V SB, and PWR OK pins so I can have an indicator of the power supply (PS) being plugged-in (D1) and another for the PS being turned ON (D2). The diagram below illustrates the connections.

I also connected the 12, 5, 3.3, 0, -5, and -12 V lines to the bottom-left banana connectors in order to have easy access to the power lines. Now, I can connect any ATX power supply to the box and it will work, which makes replacing a defective power supply very easy.

After making the electrical connections, the switch and LED(s) have to be mounted to the box by drilling appropriate holes.

This was a fairly easy build, with the only difficult part being to find the appropriate materials in the garbage.

I may add a USB hub or some USB connectors as well in order to have more ways of connecting things to the box.

December 16, 2008

Big Pot

I found a big potentiometer in McGill's garbage (universities' garbage is pretty good). When I found it, it was very dirty and its body was badly bent. Fortunately, I managed to put it back together and now it is shiny and fully functional (as shiny and functional as a pot can be).

Some Specs:
It is a 400 Ohms potentiometer made out of an array of thin metal hexagons and a contact point that moves along them. The number of hexagons in between one end of the array and the moving contact is proportional to the potentiometer's resistance. It is roughly 50 cm long and I bet it can handle lots of current.

Basement Cleanup

I finally cleaned up my basement/workshop and put some order into my tools and materials. My main source for materials in general is the garbage as the faithful readers may already know. Too bad I was too late for the Hacked Gadgets Workbench Contest.

My new soldering space
I also got some new tools a while ago. Note the precision screw driver holder made out of a plastic jar cap and the screw driver stand made out of a piece of wood I found in the garbage.
I also got some new measuring tools that are extremely useful (and make me extremely happy).
Some of my electronics parts:

Brass Sponge

I came around many electronics stores selling brass sponges as soldering iron tip cleaners. I thought that using a brass sponge was a good idea but was not ready to pay between 5$ and 12$ for a sponge. Instead, I got two brass sponges at the groceries store for around 1.9$ and used an old metal cover from a jam jar to make my own. The result is a very useful soldering sponge.

If you are wondering what are the advantages with respect to the more conventional wet sponge, I can enumerate three:
  1. It does not inflict such a great thermal shock on the iron tip. Thus, putting it trough less stress.
  2. It does not produce fumes since the tip temperature doesn't change as much and there is no water vapour.
  3. It does not require water. Having water around electronics can sometimes be a bit of a hazard.