Tuesday, 25 February 2014

USB Powered LED

For a bit of fun, I was looking at reusing some old USB devices. I had an old USB mouse that was past its use-by date, so I pulled it apart and did some harvesting of components.

One of the things that I was left with was the USB cable.

The cable had 4 wires and a shield. The white and green wires are Data (positive and negative) and the black and red wires are power (red = positive, black = ground). I did a bit of trimming (cut off the shield and the white and green wires) and then crimped the red and black into a DuPont 2 pin female housing.

Picture 1

I then attached some jumper wires to the DuPont so that I could connect it up to the prototype board.

Next, I made up a prototype board with some 3mm LED (8x red and 1x green), some jumpers and some 220 ohm resistors in parallel.

Picture 3

This is a pretty simple circuit, nothing fancy, just some LED in parallel and some resistors.

The positive is going to connect at the top and the negative is going to connect at the bottom.

Picture 5

I connected the jumpers from the USB to the prototype board and got ready to connect the USB to my computer. I have an AC/USB adaptor that I could use just as easily … but my computer is on and ready to rock … so, why not?

Picture 6

You can see the light thrown by the green LED in the back … it’s a lot brighter than the red LED. The red LED are about 5000mcd whereas the green is 15000mcd … so understandably brighter.

After looking up USB wiring on the Interweb, I found that the USB cable is (at 3m length) 5.1 volts according to my multimeter. Check out Pinouts R Us for more details about the voltage, wiring arrangement and such.

I guess that this would make a pretty simple power source for my electronics desk (for stuff that needs < 5VCC.

Anyway, I hope that this gives you some ideas … it has my mind going!

Monday, 17 February 2014

Moved House … again

Well, I’ve moved and I my new digs are not too big. I am now living about 760 km from my workshop, so there isn’t going to be any major work going on. I hope you all had a restful break.

I’ve been toying with making stuff for a while now and it’s time to explore another path to the goal of making steam-punk paraphernalia. This next path is going to be going back to basics.

I am going to start modelling some stuff using plasticine and then investing it in silicone so that I can make some resin prototypes. That doesn’t sounds very hard, does it?

I bought a 500g block of grey plasticine from the art store (Artery, 137 Collins St Hobart) for the princely sum of $5.55. The plasticine is Non-Toxic Belgrave Quality Modelling Clay. Now, the last time that I played with plasticine was when I was in Primary school, some time around 1976. I have some clay modelling tools (spatulas and some loop tools). I also have some Isocol rubbing alcohol, apparently this is used as a lubricant for plasticine and also for smoothing the surface.

I plan to start simply so that I can gain some skills in clay modelling/sculpting. There are a couple of things that I could start with, but what I’d like to do is to make a BeetleBot (V2). The first time that I saw this robot was on the Instructables website (by Jerome Demers). The BeetleBot is basically a pair of DC Motors, a pair of lever SPDT switches and a battery holder. The antennae of the BeetleBot are attached to the SPDT switches; when the beetle antenna hit something, it temporarily switches the off-side motor into reverse, making the BeetleBot move away from what it just hit. I’m going to add a toggle switch so that the BeetleBot can be turned off and on. There’s another guide to this simple robot that can be found on the Science Museum Learning website.

The modelling side of this project is simply to make a covering for the BeetleBot so the plasticine will be used to make the basic shape of the BeetleBot body …

Anyway … that’s going to be my first project in the new flat. Check out the links to the BeetleBot instructions and have a go yourself!

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