UptownMaker

Somehow I've become a prolific blogger lately.  I wonder if this will last... Today at work I had a serendipitous moment of seeing two desktop objects in an abnormal light: a small, scavenged lens cell and a super cheap (2 for $5) LED flashlight. As part of my on-going inculcation into the mystical arts of optical engineering, one of my fellow engineers demonstrated to me the ease with which an illuminated object can be projected onto a surface, if the various distances are correct.  His demonstration was with the image of the lit window that faces our cubes, but it occurred to me today that, by tweaking distances, I could probably get a similar image from my LED flashlight, writ large on a blank whiteboard. Tah-dah!  What's more, I found that, by moving the lens slightly along the optical path, I could bring different elements of the LEDs into focus.  But lets start by analyzing this image. First, you can see (though not very well) that the LED lenses are f...

I know some of the people who read this blog (or who will see links to this post on Twitter) are into laser diode projects, so I thought I'd throw out some of the lore I've acquired on the topic. Laser diodes... 1. ...are current driven devices: Always drive them as such, being careful to limit the current through them to some relatively safe value. 30mA is not an unreasonable guess; as they age the current required for the same output power will increase. 2. ...aren't very laser-like: Don't expect a laser diode to put out a tidy little dot of light. That requires some optics. As the current pushed through a laser diode goes up, the efficiency of the device increases, and the divergence angle of the beam decreases. The beam tends to project an ellipsoidal shape on a perpendicular surface; the larger of the two dimensions will change more as the current goes up, while the smaller dimension won't change much at all. This is why laser pointers do not project a...

The MiniPOV is an Adafruit toy that provides a discreet package for POV (persistence of vision) display. Normally, POV displays involve lights that are mounted to a moving arm or wheel. As the lights are swept across a person's field of vision, the slow response time of our vision receptors causes us to detect the changing light patterns as an image. The MiniPOV depends on a person to provide the motion. Instead of being mounted to a moving object, the user holds it in his or her hand and sweeps it through an arc, providing the motion. That's pretty cool, but it's also kinda small- it fits into an Altoid tin. I'd like to make a larger one- say, 12" long, with one LED every half- or quarter-inch. My deeply subversive application is to press this up against the window of my bus as it drives past all the suckers stuck in traffic on the highway, flashing a message to hopefully get them to consider some alternative to single-commuter driving.

I used to have one of those super fancy Phillips electric toothbrushes. One of the cool features of it was that it charged by sitting in a cradle that inductively coupled to the toothbrush handle, so the handle could be sealed water tight and yet still accept a charge. I'm fascinated by this and by the potential associated therewith. I'd love to try using this for other applications. The easiest is a setup where a coil placed under a table passes power to a device sitting on the table, and the most obvious candidate would be a reading lamp or a centerpiece that has lights involved. The result is a cool centerpiece that lights up without the inconvenience of running a cord across the table.

This is a pretty common consumer product: a device approximately the size of a votive or maybe a tealight that behaves basically like a candle, in that it has a small LED that flickers and fades. The reason I want to make one rather than just buying it is that I have a special need- to be able to turn it on and off without contacting it. A few years ago I made some balsa and paper lanterns that can be hung from the ceiling on a string. A tealight in the bottom provides nice light, and the dozen or so that I made create a very warm atmosphere in a room where they are the sole illumination. Of course, lighting all those candles is no fun. It requires hauling a chair around the room, getting up and down, and trying not to catch the paper on fire. Putting them out is similarly taxing, unless you let them burn down over four to five hours. Obviously an application ripe for electronify-ing, but an electronic light has the same problem: to turn it on, you need to get up on a chair, pull...