Sunday, March 18, 2012

Oh the many things you can do with onion skins and more mystery project

Start off with a photo of some yarn.

This is some mystery wool I dyed with onion skins (no mordant) a long time ago. I use to spin this on a spindle while waiting for the ferry to and from Seattle back when I needed to go to the States for medical treatment. I used it to knit some socks and they turned out lovely and warm. I had a whole bunch of dyed roving left over, so I thought why not spin the rest up on a wheel.

And back to the mystery project.

I took apart one of the small, broken solar lights we have. These are those little lights that you stick in the ground to light up the edge of a path, or in our case the pond. They have an AAA battery and turn on the light when it gets dark. I don't know if they will serve my purpose as I'm not sure what part of the system tells when it's dark or not.

Oh dear, I hope I'm not moving away from the world of electrics towards electronics.

I can more or less understand what's going on here. The pale green stripy thing is some sort of resistor. The solar panel produces 2 volts (thank you trusty meter thingy) and the battery needs 1.5 volts. My theory is that the pale green stripy thing is taking the 2 volts from the solar panel and reducing them to 1.5 volts so to make the battery happy. But I could be wrong.

The other side was difficult to photograph and show up the shiny paths. I am assuming the shiny patterns are where the electricity goes. (please remember they didn't cover this stuff in university level philosophy)

I can more or less trace the path and see how the switch completes the circle. What I don't understand is what does the big black dot do in the middle? I have solar panel and light and battery all feeding into the black dot. Is this the thing that tells the battery to charge during the day and the light to go on during the night?

Am I even close on any of these theories?

Any recommendations on a good book to read? I took some out of the library but they are not very informative. Most of them are kids books and say things like "get your parents to buy this Stirling engine and then look how neat it is" without actually telling us how these things work. Not really worth suffering through all that ink.


Natalie Freed said...

The black dot is probably a microcontroller, covered in resin or something like that to protect it. Could be a transistor (which allows a small change in voltage to control a larger change in voltage, so that when the light changes the resistance of one part of the circuit and thus the voltage flowing through there, current is allowed to flow to the light in another part of the circuit.

There is likely a "light dependent resistor" or "phototransistor" somewhere to detect when it gets dark, they look like this:
Or could look like a dark LED, like below:
(btw they're wiring everything up in a funny way rather than putting it on a board because they're trying to get it all on a coin cell battery, so perhaps ignore that part!)

Natalie Freed said...

I'd suggest starting with instructions for something related to what you are doing. Eg.

Josiane said...

Your onion-dyed yarn is such a beatiful, warm, glowing yellow - gorgeous!