Thursday, October 31, 2013

Design a laser-cut Spirograph-like toy

The number of teeth on the outer ring and the inner gear determine the number of "points" on the resulting full drawing. When setting out to design a spirograph, I first fiddled around with a few different size rings and gears.  I found that, for a given ring and gear size, the number of "points" can be determined by dividing the least common multiple (LCM) of the number of teeth on each of the two elements (ring and gear), divided by the number of teeth on the gear.*  

Using this equation you can make a spreadsheet with columns as ring sizes and rows as gear sizes to help you choose the numbers of teeth for the elements of your toy.

Excel has a function for least common multiple, and thus it's easy to write a formula this purpose:


where B1 contains the number of teeth in the outer ring and A2 contains the number of teeth on the gear; see the screenshot.  

...Or just download the Excel file below.

As you might expect, for rings with a prime number of teeth, the number of points is always that number.  For gears which have a prime number of teeth, they result in designs with a number of points equal to the number of teeth in the ring.

* Perhaps this value has another name, but I'm no mathematician; please let me know if there's a more simple name.

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AirAudio Makes Your Android Device Airplay Compatible

AirAudio Makes Your Android Device Airplay Compatible

Android (Rooted): AirAudio is a utility that lets you Android phone or tablet play nicely with your AppleTV, Airport Extreme/Express, or any other AirPlay compatible device in your home entertainment system. Best of all, it's free.

Your Android phone needs to be rooted for AirAudio to work, but if it is, you'll be able to push any audio from your Android phone—whether it's a streaming music or pre-recorded audio, to a set of AirPlay compatible speakers or audio devices. Once installed, all you have to do is select the available AirPlay devices on your network, set the output volume, and listen while your music comes out of the big speakers instead of the small ones. You can even play your Android's audio through multiple Airport receivers at the same time.

The app doesn't technically require Ice Cream Sandwich, but ICS users will get the most benefit. There are two audio output modes: "system audio" and "microphone." Microphone is great if you want to speak into your phone and hear it through the speakers, but "system audio" is what you really want to use. On pre-ICS devices, "microphone" is the only option, and it essentially plays your audio on your phone and uses microphone mode to pass that audio to your AirPlay speakers. It's a little echo-y, but it works, even on unsupported devices.

AirAudio is free, and it's a great option if you're rooted and running ICS. If you're not, it's still worth a try if you can't find another app that bridges the gap between your Android phone and your AirPlay speakers. Hit the link below to grab it.

AirAudio (Free) | Google Play

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Twig Candle holder

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Semi-Restore Restores Your iPhone without Losing Your Jailbreak

Windows/Mac: SemiRestore is a new app for jailbroken devices that makes restoring your iOS device to a stock-like version as easy as a click of the button.

With SemiRestore installed, you just need to run the app with your device connected to your computer. SemiRestore will go through and clean everything up while retaining both your jailbreak and you current iOS firmware. This means it deletes all your apps, settings, jailbreak tweaks, and everything else. You won't need SemiRestore often, but it's good if you need to troubleshoot some problems, or if you've just installed too many tweaks and want to start from scratch.


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A4 Suspension Filing Drawer

This is an Ikea "SNACK" box hack. A perfect upgrade from that tiny filing box with a flimsy handle that you used as a student; this filing drawer rolls along the ground and can sit unobtrusively under a bench or shelf.

I recently decided that I would transfer all my files to a hanging/suspension system. However, I didn't want a tall 4 drawer filing cabinet, and despite much searching - I found nothing in the UK that fitted my requirements of being low profile, modular and expandable. I discovered several (expensive) "Filing Benches" in the US that looked good, but despite toying with the idea of making something similar - I thought I would leave it to someone with superior woodworking skills.

So this is what I settled on - A very sturdy, mobile filing system made with simple techniques that require very little DIY skill.

Have fun playing with the design - I welcome improvements and suggestions. If you make something similar - I'd be really interested to see your take on it.

Enjoy my first instructable!

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Egg Fried Rice

P1020457.JPGEgg fried rice is an easy to make quick and tasty Indian cuisine. It takes just about 10 minutes to make this delicacy when you are in a hurry, provided you have the cooked rice ready.P1020441.JPGThe following ingredients are required to make the Fried egg rice: About two cups of cooked rice Two eggs Two medium sized onions, chopped Four green chilies A bunch of Curry leaves One tablespoon of cumin powder and turmeric powder mixed Black mustard seeds Salt to taste About one tablespoon of cooking oil

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