Funnyhacks Ep 2 - Plane

Radio Controlled models are a ton of fun, but sooner or later they end up auditioning for the trash can. This hack comes to the rescue to salvage all those great parts that are still good to convert an RC helicopter into an RC plane.

Risks

• Lithium Polymer explosions (youtube)

• Lithium Polymer precautions

Wings

Most model shops stock pre-made wings. However if you are like me and would like to make your own, you may want to read a little more about how a wing works.

• Common theory

• Alternative theory

Propella

• Propeller

• Design calculation (I have not read this)

Funnyhacks Ep 1 - Carphone

I hadn't intended to put these notes up yet, but the video is getting a lot more interest, earlier than I expected, so I thought I should put up the extra material that should help you do it yourself. If you have any suggestions, please contact me on the email address below. But firtst, the intro:

Imagine your phone is ringing and you can't find it. Probably the last thing you want is for it to be quietly driving away from you. Well that's what this one does. The concept is: Take power directly from the battery and use the vibrator power as an input signal.

My biggest mistake was underspec'ing the transistor. “A motor can draw twice its specified current as it powers on”. Once I had a more powerful transistor I tested it and the motor twitched once, then all was quiet. This was a good bit of encouragement. Everything did what it was supposed to do. It just didn't last very long before something died.

The successful transistor was a tip3055

These transistors are pretty common (uk). Having said that, I can't find it at DSE (nz), so these will also serve you well:

• 2N3055 – Even more overkill than the one used in the video.

• MJ15003 – Yet more overkill.

• MJ15004 – Even more overkill still. Mwuhahahahaaaaaaa!

I've had lots of great feed back already, but if you see something that should be different, please let me know by commenting or email me at ksandom@gmail.com. One suggestion was that I should explain more about the transistor, ie how it works and how to use it. This is too much for the purposes of this episode, but there will be another opportunity in an up and coming episode. In the mean time, take a look at:

• http://measure.igpp.ucla.edu/hemisphere/Discussion2/NPN_Transistor.htm

• http://measure.igpp.ucla.edu/hemisphere/Discussion2/PNP_Transistor.htm

• http://electronics.howstuffworks.com/diode2.htm

• http://www.corollarytheorems.com/Design/transistor.htm

There is also a massive amount of info at:

• http://en.wikipedia.org/wiki/Transistor

• http://www.explainthatstuff.com/howtransistorswork.html

I haven't read all the way through all of these links, but I have been looking for particular material in there which is likely to help you, and these links should be most of what you need.

Phone battery

This remains one of my favourite hacks. It's really simple: find out what voltage is needed and then work out how many AAs are needed to make it up. The battery for my phone is rated at 3.6v, so 3 1.2v rechargable AAs was close enough. After that, the choice of battery comes down to how long you want the phone to last. My original battery was 700 mAh, so 2000 mAh batteries wired in series gives almost 3 times the battery life.
If the battery isn't labeled, use a multimeter to find the positive and negative terminals (usually on the outside). Don't just accept the first reading since the charging terminals can output current on some batteries. The ones you want will generally be the highest voltage. Note that a fully charged battery will usually give abit more than its rating. eg a 1.2v rechargeable AA will give 1.5v and a 1.5v volt alkaline will normally give 1.7-2v.

Wiring is simple. Connect the positive and negative terminals of the phone to the positive and negative terminals on the battery holder. When I did mine, I didn't do anything with the charging terminals. This meant that I had no battery life indicator. On phones where this is the case, you might be able to get it to work by putting a resister in the right place, but I don't know. I haven't tried.

Grouphug - Clustering with an evil twist!

Of all the things that are likely to be on this blog over the next while, this represents by far the largest amount of time and effort. I've spent time on it every day on the tube to and from work for several months, and lots of my spare time. And yet... I have very little to write about it without going into excruciating detail that would bore most readers. If you are interested in that detail, I recommend first taking a look at how it works, then viewing the integrated help since the documentation is quite thorough. So what have I spent so much time on? A clustering frame work...... written in bash!

While its still got a long way to go, I've just released the first publicly available version. This version lays the foundations and is intended as a proof of concept to show that all the parts can work together.... and that they can work at all! ;) Over the next couple of months, I plan to release a number of subsequent versions that will do master and worker node fail over, monitoring and much more.

But in the mean time, take a look around.