Archive for May, 2010

DC Power Supply for Saltwater Etching Project

Posted in Power Engineering, Saltwater Etching on May 31, 2010 by themidnightengineer

What you see here is a failed attempt to convert an ATX computer power supply into a general purpose DC power supply for benchtop use. After I installed all the binding posts to the chassis and soldered the wires to the posts, as well as a 10 Ω power resistor to act as a load and a secondary switch, I plugged in the power cord and turned on the main switch. Nothing. The fans refused to whir into life as I expected. I tried flipping the secondary switch a few times and suddenly there was a loud popping sound, sparks from the board and the acrid, electrical smell of an exploded electrolytic capacitor. Three hours of work gone up in smoke, literally.

Yes, I know, my floor is a mess.

Fortunately I had another power supply that I had salvaged from an old Cisco router at work (seen above). The output is rated at +5.10V @ 24.0A, +12.10V @ 5.0A, and -12.0V @ 3.0A. I had to unscrew and take out the board to unsolder some of the extraneous wires. Each of the four binding posts has its own color (red, black, yellow, and blue) to match with the color of the corresponding wire. Each post can accommodate a banana plug cable. I ordered all of the parts from Mouser.

You have to be very careful working with power supplies because some of the larger capacitors still carry charge even after the unit is powered off. If you touch a lead on the board connected to the capacitor you can get electrocuted.

I plan on using this power supply for an impending project for etching designs on Altoid tins.

Slicing Beer Bottles

Posted in Bottle Cutting, Redneck Technology on May 30, 2010 by themidnightengineer

I resumed my nocturnal bottle cutting activities recently. Bottle cutting is an obscure art. Not many people do it and there is not a lot of literature on how to do it.

Glass is a difficult material to cut properly. If the molecular structure of glass were crystalline, like metal, this would all be so much easier. But unfortunately, glass is an amorphous fluid. That means any attempt to cut glass may produce unpredictable results.  The cutting of glass itself may be best described as “controlled shattering”. Ideally, we want it to shatter in a straight line.

In order to cut glass, you must first etch a line with a glass etching hand-tool. Etching a line on a flat piece of glass with a straight-edge is easy enough but etching a straight, even line around the curved surface of a bottle is a totally different matter. That is why I built this custom-made device. There is no other device like it in the world!

This is how the bottle goes onto the device. Everything has to be measured and calibrated precisely, which is why you see an architect ruler in the photo. The bottle is slowly rotated with manual pressure applied. A cutting bit underneath etches a straight circle around the bottle. BTW, that happens to be a Heineken beer bottle.

The etched line must be heated with an open flame. I use a propane gas torch, which can be bought at Home Depot. Some people suggest using a candle flame but based on my own experience, I do not recommend it. A candle flame will leave a dark ash residue around your bottle. On the other hand, the propane flame burns cleanly so it won’t leave a residue. However, it’s much hotter than a candle flame so you have to be much more careful when heating the bottle. Apply too much heat and it can crack the bottle rather unceremoniously.

After the bottle is heated, you dunk it in a large container filled with cold water. When a material is heated, it expands. When it is cooled, it contracts. The idea is to use this expansion-contraction to apply shearing stress along the etched line around the bottle, thus leading to a controlled shattering.

So here are some sample of bottle that I have cut in the past. The cut edges are very sharp and jagged. It needs to be grounded down with an angle-grinder power tool.

Why cut bottles? I really don’t know how to describe it. As I mentioned before, it’s not easy. It takes skill, discipline, and lots of patience. But it is a very satisfying feeling to be able to perform a difficult task and do it well. On a practical note, I plan on using these cut bottles as containers for my impending project, which is making soy wax candles.

Completed my VFD Tube Digital Clock

Posted in Ladyada VFD Tube Clock on May 30, 2010 by themidnightengineer

I love the retro look of the tube contrasted with the clean, modernistic laser-cut acrylic enclosure.

Form + function = good design.

Good to know that my EE degree wasn’t a complete waste

Posted in Ladyada VFD Tube Clock on May 30, 2010 by themidnightengineer

IBD’s 10 Secrets of Success

Posted in Miscellaneous on May 30, 2010 by themidnightengineer

1 HOW YOU THINK IS EVERYTHING:
Always be positive. Think success, not failure. Beware of a negative environment.

2 DECIDE UPON YOUR TRUE DREAMS AND GOALS:
Write down your specific goals and develop a plan to reach them.

3 TAKE ACTION:
Goals are nothing without action. Don’t be afraid to get started. Just do it.

4 NEVER STOP LEARNING:
Go back to school or read books. Get training and acquire skills.

5 BE PERSISTENT AND WORK HARD:
Success is a marathon, not a sprint. Never give up.

6 LEARN TO ANALYZE DETAILS:
Get all the facts, all the input. Learn from your mistakes.

7 FOCUS YOUR TIME AND MONEY:
Don’t let other people or things distract you.

8 DON’T BE AFRAID TO INNOVATE; BE DIFFERENT:
Following the herd is a sure way to mediocrity.

9 DEAL AND COMMUNICATE WITH PEOPLE EFFECTIVELY:
No person is an island. Learn to understand and motivate others.

10 BE HONEST AND DEPENDABLE; TAKE RESPONSIBILITY:
Otherwise, 1- 9 won’t matter.

From the Investor’s Business Daily.

Hello world!

Posted in Uncategorized on May 30, 2010 by themidnightengineer

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