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gotwind
Forum Admin
United Kingdom
958 Posts |
 Posted - 01/12/2007 : 22:07:50
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I've had a nice email from a guy named Dennis:
"Attached is a shot of my Wind turbine, this is the outdoor decoration for this year.
It's green, red and flashy but goes in a spin.
Power is from the usual Sturmey Archer hub, lighting 12 red LEDs, 4 on 3 blades with a further 3 blades being plain, total diameter about 1 m.
The large number of blades help to keep the speed down as I was a little worried about the wiring getting broken if high speeds are reached..
This looks very spectacular at fast speeds and can be seen for over 1000m."
Hopefully we will get a few more details on how this was actually achieved i.e wired up without tangling wires?
I guess the external hub itself is supported and the prop was directly connected to the axal and wiring fed out to the blade Leds- I like it...
A very effective free Christmas decoration. Can anyone do any better?
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gotwind
Forum Admin
United Kingdom
958 Posts |
Posted - 02/12/2007 : 15:09:46
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A little more info off Dennis:
Wiring layout is very simple, you fix the outer shell, then let the axal and generator assembly rotate. The blade assembly is bolted via the axle. Each blade is wired in parallel back to the terminal strip on the blade hub. The feed wire passes threw the plate hub to the generator.
The day shot is attached and the LEDs can still be seen, these actually show from all directions
Dennis
The Futures Green - Getwind of it. |
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DuffDe
Starting Member
USA
7 Posts |
Posted - 02/12/2007 : 17:32:08
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Not so much a Christmas picture, but a picture of Winter efffects on blades. I'm so glad I spent a lot of time balancing those blades.
Actually both turn. Not quite to speed. We are expecting higher winds later so that will be interesting to see.
The lighted blades is a very neat effect, hopefully we'll get to see a "how he did it". |
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gotwind
Forum Admin
United Kingdom
958 Posts |
Posted - 05/12/2007 : 19:15:42
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Dennis.
If you read this forum,
Are you using some kind of voltage regulation with your led's?
Fungus made a nice regulator with an AC input of up to 30 volts.
Perhaps he could supply the schematic of the design here for all to make up on veroboard (strip board)
http://gotwind.forumco.com/topic~TOPIC_ID~323.asp
Ben. |
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fungus
Moderator
301 Posts |
Posted - 05/12/2007 : 19:43:21
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| It was only a simple 7812 regulator with a capacitor to smooth it - I could make up a quick schematic if needed? |
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gotwind
Forum Admin
United Kingdom
958 Posts |
Posted - 05/12/2007 : 19:46:02
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Yes please Fungus - appreciated by the forum and me...
The Futures Green - Getwind of it. |
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fungus
Moderator
301 Posts |
Posted - 05/12/2007 : 21:01:49
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here you go... hope its understandable :)
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ghurd
Junior Member
USA
314 Posts |
Posted - 06/12/2007 : 16:53:03
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With the 100uf+ cap, the 0.33uf seems about pointless?
Nice schematic. And under 10Kb - filesize!
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fungus
Moderator
301 Posts |
Posted - 06/12/2007 : 17:20:11
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| I'm not too sure .. but theres no harm putting it there :) |
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llerdnaj
Starting Member
United Kingdom
16 Posts |
Posted - 06/12/2007 : 22:05:04
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Fungus is correct. Damn I wish i was 14/114. He's got some good tutors!!!
Scoundrel |
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fungus
Moderator
301 Posts |
Posted - 07/12/2007 : 12:54:26
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| 15 now actually :) |
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DENNIS A
Starting Member
United Kingdom
16 Posts |
 Posted - 13/12/2007 : 20:54:53
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 Hi Fungus
re you proposed control curcuit.
I intended to make the decorative windmill with alternate red and white arms, any flicker would be left in as it looks nice.
A small rectifier was positioned before splitting the wiring to the arms and each arm was in parallel so that no resistors would be required.
24 off LED were selected requireing 0.48 amps, the SA unit can produce 0.5 amps. It was expected that the red LED would light first, when the white would light as the revs/voltage increased.
Unfortunately the proposed system would not work with the white LED installed. These were taken out.
It was found that with red LED only the SA unit generated 4 volts at 60 rpm increasing to a max. of 5 volts at 120 rpm and above.
The voltage after the rectifier was only 2.5 volts and this it was suspected was below the working voltage of the white LED.
If the white LED were installed before the rectifier it still failed to work so I considered that I was using too many LED.
Bench tests concluded that 6 LED 2 per arm worked again wired in parallel.
The questions raised, will the AC current on the white LED cause an early failure,
Can the wiring be layed out to give more LEd powered by the SA unit.
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ghurd
Junior Member
USA
314 Posts |
Posted - 27/12/2007 : 08:47:01
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You are thinking linear. LEDs are not linear. Ohm's Law does not apply in the traditional sense.
The red LEDs used ALL the power. They held the voltage down to the red LED forward voltage, which is below the white LED voltage. They hit the max forward voltage of 2.5V, and somewhere before that they started acting like Zener diodes.
They will continue to use ALL the power... until they all <pop>. Then the white LEDs will light.
The idea "that no resistors would be required" was the entire problem.
(Q:How many amps does it take in a 1N4001 before the forward voltage reaches 3.6V for a white LED to light up with 20ma?
A: Who cares? The planet will explode before that happens.)
AC current will cause an early failure. White, red, yellow, green, plaid... LEDs.
The current must be maintained to WELL below the max, which can not be done without a resistor of some sort.
The reverse open voltage will kill them if the amps don't. It is usually listed at 5V.
Long story longer, they MUST have resistors and they must be fed DC (meaning after the bridge rectifier).
Try it again with 180 or 220 ohm resistors in both the red and white legs. Then it'll work.
Might read this too...
http://www.gotwind.org/led_experiments.htm
G-
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Christmas wind decorations
