Assistance with Computer Generated Electric Charge..

[brandon184]

Hey,

I'm working on a rocketry project, and I want to make a device that I can connect to my PC that will generate an slight electric charge (enough to create a few sparks), when commanded to do so by software.

How on *EARTH* would I go about doing this?! I have absolutely no idea where to even begin.

- Brandon

[wahrez]

I suppose you would need to build a small circuit board which accepts inputs from perhaps a serial connector.

The circuit would then use an XOR gate to activate a charge through a capacitor???

I did build something similar using a Serial connection between a PCB and my computer about 8 years ago.

I wrote software which issued a command and transmitted a 1 or 0 down the serial cable.

I haven't done microelectronics for a long long time, so this may be out of date now?

[brandon184]

^!^

[DanU]

You could try controlling a spark generator from the serial port. The spark generator could probably come off of your BBQ grill or your gas stove if they're equipped with one.

Since you only need an on-off interface, you could simply use one of the signalling lines of the serial port (like DTR/DSR or RTS/CTS) to control a relay which would switch on the spark generator.

Let us know what you come up with.

[qwerty12345]

You could just use simple inductor to generate the spark. When you take the voltage off an inductor, its magnetic field collapses and can generate quite a nice spark. I think this is how spark plugs work, but making your own could is an alternative. I've seen an inductor generate a good voltage after having a 1.5V battery on it (The generated voltage was high enough to push current through about 20cm of human flesh, ouch).

[Joe03]

I've made one of these model rocket launchers before, here are a few tips:

The serial/parallel ports can't provide more than 5 ma of current, so you need to build a transistor amplifier if you want to power a standard ignitor.

Building a comp controlled launcher is very dangerous, since the serial ports and parallel ports can activate at any time without warning. Sometimes windows will check the ports to see if a device is present, so make sure to include a mechanical safety switch in the line.

If you still want to build it, you can use basic or c++ to write a simple exe that will output high on one of the serial pins. Search the web for any simple npn transistor amplifier circuit (a very simple one (5-10 components) should work, you don't need to use a complex circuit designed for audio. I would suggest using a transitor rated 40 watts or better.

I'll see if I can dig up the plans for the one I built - It's been a while since I last used it.