How to make use of old PC power supply

I have 3 of those old power supply. At least 2 of them still works.Here is how to make use of the thing for power supply for other purposes.

This power supply has 5volts, 3volts, 11 (or 12?) volts and -11volts power. This is nice for electronics projects. For example, some IC's like the DAC requires negative voltage. It is available here without having to buy negative voltage generator.

Best of all, electronics dedicated power supplies costs at least RM100 or usually more. But in this case it is much cheaper. RM50?

The trouble is when you simply hookup this power supply to the 230volt supply,it will not work. Here is the trick that would make it work.

The black wire is ground. Using a multimeter, check each connectors and you'll find at least one wire with 3V and one with 5 V.

Most of the wires are red, black or orange. The other colours are one each.

Using 1kohm resistor, connect the 3V line to the other wires (not the red or black)one by one while monitoring the voltage across the black and redwire. Best to try connect the unique colour wires first to the 3 volt line. When you register 5 volts(or 12volts) across the black and red wires,the power supply unit is ready to go.

In my case, the 3 volt wire is green, and need to be connected to white wire for the power supply to work. Now I am off to do some projects..

Robot building: 1st post

Okay, this is my real 1st post.

I’ve promised my son that I’ll show him how to make an autonomous robot by the time he reach 9. That was 2 years ago. Now he is almost 10. That promise was never fulfilled.

Guilty conscious, I have scrambled for the past several months to find ways to get it done. Luckily, I saw one advertisement for a workshop on robot building for 9-12 year olds during one of the school holidays. I sent my son, and his cousin, for that one day workshop. It cost me RM125. There, they were taught how to build robots by using the LEGO Mindstorm set. Interested, I asked the instructor how much it would cost to buy one of those sets.. RM3000! I later asked Sasbadi (the agent for LEGO Mindstorm in Malaysia) and found that the minimum set would cost me around RM2000!

I feel that it was too expensive. And I was convinced that to make the robot from scratch would be more fun.

Electronics is not my area, let alone robotics. However, I was determined to learn and build one on my own. I own one Parallax Basic Stamp2 microcontroller, which I bought six years ago. One good thing about Parallax is that they have good website with a lot of information. They also have robotics teaching modules for their Board of Education single board computer (?). That would be useful.

Here is the plan for the robot that I would like to make. I used a cheap radio control car as the base with all the drive motor, steering motor, wheels, and the chassis. This cheap RC car employs DC motors only. There is no servo motor. I will have to figure out how to drive this motors.

Since it is based on a RC car, I need to figure out how the robot would have to maneuvre e.g. through obstacles etc. with a slightly different technique as opposed to using 2 servo motors.

I plan to have photo sensors to make the robot either folllow or run away from bright light.

I will put the detail of the parts list in the next post.