Need Ideas for College Project

[Vincent]

I have been assigned to do a collage for an art project that is based on our interests.<p>It can be more than just pictures on a paper. He described a previous project where Christmas lights were used around a cardboard box, etc. <p>So, now I have the desire to do something with electronics. I have around 5 very bright blue LEDs I plan to use. I would like to have something motorized as well with sound. I have an amplifier out of a computer sound system. <p>I'm hoping I can find a transformer that converts the 120vac to a DC supply voltage I can use to run everything off of.<p>I'm new to building this stuff, so I mainly need some ideas and probably some help putting it together. <p>I mainly want all the electronic components involved for looks. It still has to consist of pictures of my interests which are stereos, automobiles, etc.

[perfectbite]

Don't bother with 110V, we're not talking about a lot of power here and 110 can be hazardous. Keep it simple. Don't hide any of this, make it part of the collage. Use one each of an AAA, AA, C and D batts (decorate them if you want but leave the contact ends alone) connected to give you 6.0 DC volts and mount them on the collage. LEDs like about 4.5 volts generaly and these really poor connections are going to soak up a volt just to get by them. Use clean bare solid copper electrical wire (bent to fit) for the base rail mount and low pressure springs to connect each battery to a wire top rail. Use glue on the non contact areas. A freely hanging strip of tinfoil (with fuzzy dice hanging from it) contacting a fixed strip of tinfoil at its bottom when blown on could be the switch or build a hands on oversize tinfoil/papier mache spring open switch (Frankenstein's lab knife blade type switch or doorbell button type or, for your interest, an oversized auto ignition switch or car horn button or car radio front). Place the LEDs in a ring or line with a resistor to each LED and flash them all at once, just once, when the switch is activated. Don't 'lean' on the switch. I take it this collage isn't going to have an extended run at the National Gallery.<p>[ June 05, 2004: Message edited by: perfectbite ]</p>

[haklesup]

If you don't want to mess with batteries, a wall wart style transformer will do just fine. They come in AC and DC and a variety of voltages so check the specs printed or embossed on the side.<p>Almost any DC voltage less than 12V and more than 5V will work if all you want to do is light some LEDs. Only the series resistor value would change as a result of changing the voltage. If you have an actual circuit to power, the proper voltage should be selected.<p>To select the resistor all you need is ohms law. A typical Bright Blue LED might take 50mA at 1.7V (check the specs on yours or look at several similar in a catalog and make a best guess). If your supply is 12V and the LED is 1.7V then you need to drop 12-1.7=10.3V across the series resistor. V=I*R or 10.3=0.05*R so R=206 Ohms. Adjust the formula for your numbers. Round R to 200 or 210 and it will work fine.<p>For more than one LED it is best that each have it's own series resistor and the LED,R combinations be paralleled. You can also put 2,3 in series but never parallel LEDs without a R for each branch of the circuit.

[jwax]

How about a sheet of thin aluminum foil stretched over a woofer cone, and allow the lights to bounce off of it onto a mirror, while you play different styles of tunes? Depending on where you locate the light(s) you will get a variety of effects.
John