Comments on: Solar pendulum

By: Owen

Owen — Wed, 04 Jan 2012 21:06:43 +0000

Hi Rick, thanks very much for your comment, the array of pendulums is a really nice idea. I might have to have a tinker and see if I can get something like it working. I’ll have a look into the magazine you mentioned too, it sounds interesting.

By: Rick Bastian

Rick Bastian — Wed, 04 Jan 2012 20:07:33 +0000

Hello Owen, saw your pendulum article in MAKE. I had an idea for a line array of pendulums, where each “tickles” the one next to it, kind of like a series of dominoes. Also, if you can, check out the now defunct English magazine called “Everyday Practical Electronics”, I think they might still sell CD-Rom copies of issues. They stopped publishing around 2002. They had lots of nice articles on solar powered led flashlights, pendulum circuits and lots of PIC projects. Hope that helps. EMAIL me for more discussion if you like. – RICK

By: doug

doug — Sat, 12 Nov 2011 19:03:27 +0000

I saw this in the Make: magazine and decided to kill some time on a sat morning to make it. I had everything in my lab except for the coil.

I tried a voice coil from a hard-disk read arm–did not work. Found some other coils in my tons of harvested components…no luck.

I have tons of magnet wire of varying gauges, but the challenge of winding a decent coil seemed daunting.

Then I came up with a brilliant idea. I took an axle from my pile of Lego technics parts (I probably have about $10,000 invested in Lego parts…LOL). Then I took two of the thin Lego wheels and placed them on the axle separated by about a quarter inch or so. I attached the axle to my drill motor and wound the wire on to the axle…continuously moving the wire back and forth to get a nice coil. I left the wheels and axle intact and wired p the circuit…Bingo!

By: edward

edward — Sat, 06 Aug 2011 19:05:41 +0000

I had same problem for days scratching head, its breadboards they have potential differences in places that are not supposed to, like rows are suppose to be independant but they arent copletely got 0.6 volt difference when should be 0,,,, grrrrr

By: Owen

Owen — Fri, 24 Jun 2011 09:26:44 +0000

Hi Kris,

I’ve updated the post with a parts list.

By: Kris Wotipka

Kris Wotipka — Fri, 24 Jun 2011 09:01:56 +0000

Can you add a parts list? Some of the values are difficult to read.

By: Larry

Larry — Fri, 12 Nov 2010 21:24:17 +0000

I suggest that the problem of the coil’s being always on is that the transistors are incorrectly connected. The wiring diagram is not much help in that regard.
After the coil works properly: The system appears to be based on the circuit’s pulsing the electromagnet at exactly the time the pendulum goes past it — or slightly after. Therefore the circuit must oscillate at the period of the pendulum. Adjust the pendulum length to match the oscillator circuit’s timing.

By: Kyle

Kyle — Tue, 06 Jul 2010 04:49:37 +0000

I am actually having the exact same problem as Randy of the coil constantly on. However, in addition to the coil being always on, the LED is always on too. I have tried the solarbotics coil, and a homemade coil, and gone through several transistors. I do have the “mysterious diode” too.

Right now I have the circuit connected to two AAs, and when I disconnect them the LED just slowly fades.

By: Owen

Owen — Thu, 24 Jun 2010 19:21:22 +0000

Hi David,

Sorry about the lack of labels there, that’s just laziness on my part. The mystery component is indeed a diode. Any small signal diode with a low voltage drop should do the trick.

I’ll get a properly labelled diagram up shortly and let you know when it’s done.

By: David

David — Thu, 24 Jun 2010 19:11:47 +0000

I’m thinking about building this pendulum for fun, and I’m looking at the circuit diagram.. I’m sure I could figure out what the various polarities and terminals all of these components have, but it would certainly be nice if they were labeled (especially the transistors) so I didn’t have to reason it out.

Also, what’s the mystery component with a single black bar on it? I’m not familiar with that as being a standard symbol. Is it a diode?

Thanks,
David