Sunday, 23 May 2010

Free electricity (-ish)

This is my experimental recycled solar panel made from old garden night lights. I got 9 lights from nice people on Freegle (Freecycle), but unfortunately one solar cell was broken when I tried getting it out of the casing. I still have 8 which generate a decent 10 volts in bright light, more than enough to trickle charge the 6-volt wet cell you can see in the photo. The sun had gone in and I was only getting 4.05 volts at this point, but not bad for a first attempt. I reckon that an array of 12 cells x 3 (36 in total) would give a usable 6 volts charging supply for emergency lighting.

Wednesday, 12 May 2010

Micro Wind Turbine

I've finally started to experiment with micro wind power and here is turbine 'Test 1.' It's made from bits of everthing. The blades are from a defunct ceiling fan and the hub is the base of an old desk lamp that stopped working. All the nuts and bolts came from a broken desk fan and I'll be using other parts of that for gearing and drives later on. The motor drove the radiator fan in a Japanese car and will be used in reverse, as a generator. The idea is to generate a useful 12volts to charge a couple of car batteries for emergency lighting use. As we live in a town, siting will also be a big consideration to keep it safe and so it doesn't annoy the neighbours.

The blades are temporary and will be replaced by ones made from sections of 110mm soil pipe, although the angled brackets they will be mounted to are ideal for getting a pitch. I don't see the motor acting as much of a generator without being turned at high speed so I'm looking at using old bicycle parts to introduce some gearing (1:5 or 1:10, something like that).

The big problem so far is a lack of wind to see if it will turn. The kids' little windmill acts as a kind of wind speed indicator!

Tuesday, 4 May 2010


I was about to buy a couple of LM35 temperature sensors and then found some LM35DZs in a box of surplus stuff I got about a year ago. These are a really easy to use component, they operate from a 5v supply and output a linear voltage at 10mV per degree C with 100 degrees giving 1 volt.

I hooked one up to the PIC voltmeter project which reads 0-5 volts as 0-1023 points and got a reading of 16 which equated to roughly 7 degrees. I'll need to spend more time on this because the room was clearly much warmer than that, but when I held the LM35 between my thumb and finger the reading rose steadily.