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[freddie ferret] 20/5/2013 17:44

Kites are best used to power transport, for example to move sledges in antarctica.

[dysonhooverman] 19/5/2013 21:42

How would you convert the vibration in a string to useful work? I see so many kites making so much power and can't help thinking there is a ton of energy to be made from the string tension as they cover a huge chunk of sky at speed.

[freddie ferret] 02/11/2012 17:29

Have been playing lately with an old three bladed fan, this sweeps a diameter of 14 inches, it is made out of cheap plastic. I have reduced the size of the blades a bit and done a bit of aerofoiling. Right connect this up to a bicycle rim dynamo through a not particularly energy efficient shaft bearing assembly and it will light a 9V .5A brightly in a strong wind (near gale). Calculations based on the fact that in order to light a bicycle lighting set (one bulb of 6V .5A and one bulb of 6V .1A) the bike has to be moving at over 7mph suggest that this assembly is easily exceeding 3000rpm and more likely 5000rpm. In gusts the bulb lights very brightly 9V .5A.



Right connecting up this same fan to a chunky 12V electric DC permanent magnet motor in a strong wind a 12v 21W bulb lights up moderately, improoving in the gusts. This motor is quite large around three inches long and two and a half wide.


EDIT

Have also been playing around with a small fan four inches in diameter connected up to a small DC permanent magnet motor. This set up is able to light a 9V .35A bulb brightly in gusts but is very wind speed sensitive. Was rather surprised by this.

Am currently modifying my views on fans and turbines.

I tried the above fan and motor combination in a strong gale, force 8ish, kept getting knocked back. In the gusts this very small fan was able to light a festoon 12v 10w bulb very brightly. It seemed very wind speed sensitive, dying between gusts. The RPMage in the gusts was very very high.

[freddie ferret] 14/4/2012 16:42

The home made dart shooting airgun continues in its development. Glueing the plastic pvc tube to the stop end has prooved troublesome. Acquiring the drawn seamless aluminium tube with a suitable bore was difficult however this is solved. The choke (constriction) is to be made from a section of the aluminium tube cut and reduced in diameter, this will be soldered in place using patent "solder it" aluminium solder.

[freddie ferret] 14/4/2012 16:27

Have recently acquired two probably knackered cordless electric drill batteries. I measured the voltage accross the terminals the first was 2.3v the second 4.2v. I scratched my head and decided to open them up. I then measured the voltage accross each of the cells, since these batteries were 12v they each had 10 cells. For the first battery two cells both registered over 1.1v and the other 8 cells near enough zero. For the second battery 4 cells registered around 1.1v and the other 6 cells near enough zero. I scratched my head and thourght about what I had read on wiki about NiCd batteries, to cut a long story short the better cells start reverse charging the weaker cells and knacker them.
So if I now connect similar cells together that are still showing good voltage can I buld up a decent battery again? I am gong to try this. Should I first fully discharge the cells to avoid a memory effect?

[freddie ferret] 10/1/2012 16:54

Have been playing around with a redundant cordless drill 14.4V type. Flicking the chuck round by hand will light well a 9V 0.5A bulb this is with the thing set on the low gearing.

Also have been playing with an old microwave cooker which I have dismantled, the motor that turns the plate is small and very highly geared rated 30Vac 4W 5-6rpm. Turn it by hand with a fair effort and 60-100v comes out, it severly hurts the tongue more surprising connect a 6v 0.1A bulb accross it and one gets a faint red glow.

[freddie ferret] 30/12/2011 15:23

Seems I am going to need a "hot mirror" rather than a filter. They are used in double glazing, photography, and oven doors.

[freddie ferret] 12/12/2011 16:43

Been playing around with some small polycrystaline solar panels for charging NiMH and lead acid batteries. Right I believe to get a decent charging current you need to use a very high over volatage as measured accross the panel unloaded. Thus I am currently using a panel producing 10.5v to charge a 6v small lead acid accumulator. Tried to use a 7.5v panel to charge the accumulator and the current flow was unmeasureable. With the 10.5v panel in the circuit the current flow was measurable.
Also tried using a parabolic mirror, (silvered satelite dish) to increase charging rate/voltage. The mirror greatly increases the current that a panel is capable of producing but the voltage only rises marginally over bright sunlight. At the moment I can get a current with the mirror of about 3-4 times that of direct bright sunlight. The limiting factor seems to be the heating effect on the panel and I will shortly try filtering out the IR part of the spectrum thus allowing more intense mirroring to be used. I may also try channel type mirrors which will not need reorientating as the sun moves round. With filters and the correct mirroring I see no reason why the current output of a panel should not be boosted ten fold.
I have also in the past considered heat sinks but do not currently intend to go down that route.

[freddie ferret] 16/3/2011 15:34

Using a parabolic mirror to concentrate the suns rays on to a solar panel results in too much heating. The question is by filtering can one reduce the heating effect to a satisfactory level while at the same time enabling an enhanced electrical output from the panel to be achieved. The question is one of filtering out the unused (by the panel) frequencies. One could of course try cooling the panel as well.

[freddie ferret] 14/2/2011 17:33

Have recently been playing with an old bicycle tyre dynamo. Right you take a 7.5 inch diameter plastic fan from an old fridge, modify the dynamo wheel with a bit of filing then clamp the fan in between the wheel and the nut. These dynamos are rated 3w at 6v the wheel is about one thirtyfifth of the diameter of the bicycle wheel. So one turn of the bicycle wheel produces 35 turns of the dynamo armature. It is normal to get the bicycle going at a good walking pace before any light is available from the bike lamps and really about 6mph is required for a decent light. On a bike the bulbs are normally .5A 6v front and 0.1A 6v back. So how well would you expect our little fan to work on the bike dynamo? The answer is very well in a gale it was lighting a 0.5A 9V bulb brightly, in a fresh breeze it was lightling a 0.1A 6v bulb, which just goes to show the cube operator in the wind velocity energy equation. So how fast was the fan revolving? I believe it may have got up to 3000rpm in the stronger gale gusts certainly 2000rpm. For me interesting!

[freddie ferret] 07/12/2010 18:30

Still a bit TS

[dysonhooverman] 05/12/2010 14:06

Hello Ff. I was very interested to hear you were looking at 240v windmills. Care to put some flesh on the bones or is it top secret still?

[freddie ferret] 04/11/2010 17:34

DysonHooverman.
As I mentioned it produces AC, appliances that use 12vac are very unusual, you first have to rectify your ac to dc (sounds fun!) with a bridge rectifier (5 diodes) in passing electicity through a diode you loose around one volt.
Anyway took it out today for a trial spin with a seven and threequarter inch fan on it, it went up to 24vac momentarily and was hitting up to 20vac quite often. I have yet to get it to light a .35A 9V bulb suggesting that it is not capable of putting out 3 watts even in the gusts. However 3 watts while seeming rather small will easily cook many nickel metal hydride batteries if care is not taken. Will have to get a smaller bulb to test what it is capable of.


Have also acquired a number of other motors that work on the same basis for conversion to generators, these are all larger having four or more coils instead of two, and far more space for stronger magnets.

What I am really after doing is producing an alternator that is brushless and capable of producing 150-350vac and around 6-15w for use with low energy light bulbs. The low energy light bulbs will operate over a large range of voltages they just get brighter as the voltage goes up. (And possibly produce more shorter wavelength radiation?)

[dysonhooverman] 04/11/2010 09:08

That's pretty cool!! (And more at my level). What's the best way to store output for use in a 12v appliance or can you connect it straight into a notebook pc and charge the battery?

[freddie ferret] 03/11/2010 13:03

The new generator produces 5vac when the axel is flicked in the fingers or 11+vac when one winds a bit of monofillament round the axel and pulls it.

[freddie ferret] 01/11/2010 17:19

Have converted a small (ex fan heater) self exciting ac electric motor into a permanent magnet ac alternator, the magnets move, the coils remain static and there are no brushes. Not rocket science but a first for me, it works, good electric shocks through tongue when I flick the axel with my fingers!! (I enjoy!)

[freddie ferret] 06/10/2010 17:21

The next topic is that of the magnetic oxygen concentrator. Neodynium magnets are very powerful, oxygen is paramagnetic (liquid oxygen very much so). I believe an oxygen concentrator is possible built on the basis of a cascade, the way it would work is you create a fast flow of air in a tube (use an old Hoover Junior upright vacume cleaner, the tube devides into two, at the division you have a Neodynium magnet adjacent to one of the entrances to the two tubes thus you get a higher concentration of oxygen into that tube, go on a bit further and that tube again devides into two, adjacent to one of the entrances is a Neodynium magnet. Repeating this (many times) you should I think substancially raise the oxygen concentration of the final output. Of course a lot of oxygen will be lost on the way in the output of the many second tubes.
A similar type of idea is used to concentrate U235 by the centrifuge process, a cascade of centrifuges is used.