This paper dial makes selecting current limiting resistors a snap. [Giorgos Lazaridis] came up with the tool, which he describes in detail in the Worklog tab of his writeup. If you want one of your own he also posted a PDF which you can print, cut, and tack together.
At this point we can calculate resistor values for LED circuits without looking at reference material. But it wasn’t always like that. This wheel will be a fantastic tool for those just starting out in hobby electronics who are trying to grasp the theory behind lighting up a simple project. The outer wheel references the source voltage, with the inner being a gauge of forward voltage across the LED(s). Line those two values up and you can read the optimal resistor value in the window seen to the right. But wait, there’s more! As you can see in the video after the break the opposite face of the dial also includes a window which will tell you the power dissipation so that you may choose a properly rated resistor. Slick!
Continue reading “Papercraft dial is the slide-ruler of current limiting resistors”
[Doug Paradis] found a simple way to use dials instead of hands on a clock. Actually, that’s pretty much the entire hack… use dials instead of hands. He grabbed a battery-operated clock movement from the hobby store, then printed out one dial for hours, another for minutes, robert’s your mother’s brother, and you’ve got a new clock. The case seen above is laser cut, with a window and index line that helps you read the time precisely.
But instead of building a case, we’d like to try this with some retro equipment. The first thing that pops to mind is to replace the disks on a broken strobotuner, like the big-dialed model that Conn used to make. If you’re not down with the bulky music hardware-turned-clock perhaps there’s an old multi-meter, or a panel gauge that can be repurposed for this. We know [Doug] already has some needle meters sitting around that would be perfect for this.
PVC, wood, and some creativity bring this Stargate duplicate to life. [Mango] and his father started with AutoCad drawings taped together, and ended with the Stargate you see before you. Sure it’s not 22 foot in diameter and not made of Naquadah, but its inner ring rotates and dials like the real thing and it has all 39 symbols – hand carved. Catch a fun and entertaining video with the Stargate after the break.
Continue reading “(Real) Stargate built in backyard”