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Forum Index : Site News : Added pages and removed diary

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Gizmo

Admin Group

Joined: 05/06/2004
Location: Australia
Posts: 5019
Posted: 11:18pm 14 Oct 2009
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Added pages about Dave's pedal generator and Gordon's cap modification to the main site.

Removed F&P Murries diary, Murry is a busy person and it hasn't been updated in years. The posts ( there were only 2, and one of these was in the wrong section ) were moved to Windmills.

In the process of removing banner advertisements from the forum for forum members, replacing with news feeds. In the future, once I've finished the modifications, only guests will see advertising banners.

Glenn
The best time to plant a tree was twenty years ago, the second best time is right now.
JAQ
 
oztules

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Joined: 26/07/2007
Location: Australia
Posts: 1686
Posted: 01:49am 15 Oct 2009
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Gizmo, I think this bit needs some modification:
[quote] Please note, the capacitors in these circuits can store a lethal charge. If the windmill is run without a load, even if just for a few seconds, the capacitors will charge to several hundred volts. Even if the windmill has stoped, the capacitor charge will remain and must be considered lethal. In all circuits I've added a bleed resistor ( R* ) across the rectifier outputs. This should be a 10k 5 watt resistor. A better option is to add a resistor across each capacitor, use a 100k 1watt resistor. When performing any maintenance on a capacitor modified alternator, please remember to test for any stored voltage with a multimeter before touching any connectors. Even with the bleed resistors, it would be worth while using a 47ohm resistors and shorting clips across the capacitors, just to be sure. [/quote]

It is a good warning, but following the instructions [quote] A better option is to add a resistor across each capacitor, [/quote] will result in destroyed back to back capacitors.

Nothing must be allowed to touch the intermediate terminal between back to back caps. The R will destroy the assymetric leakage current.... which protects the oxide layer.

A resistor can go across a capacitor pair in the dc back to back system, but not across each capacitor..... there is a cap thread somewhere you can read if you have a few hours... it's all in there.

It must be mentioned, that a bleeder across a back to back pair will result in no potential left across the pair ( it will bleed off to zero), but full potential will remain across one of them until the leakage bleeds it away.... so some physical mechanism needs to be in place to make it impossible to get to the middle terminal as it will be alive.... but as a unit it will be benign with a normal bleeder as would any AC capacitor with a bleeder resistor..... they must be treated as a unit only, not individual caps.




..........oztules
Village idiot...or... just another hack out of his depth
 
Gizmo

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Joined: 05/06/2004
Location: Australia
Posts: 5019
Posted: 05:20am 15 Oct 2009
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Good info there Oz. Is it OK if I quote some of what you said?
The best time to plant a tree was twenty years ago, the second best time is right now.
JAQ
 
oztules

Guru

Joined: 26/07/2007
Location: Australia
Posts: 1686
Posted: 06:18am 15 Oct 2009
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If you can make something useful out of my drivel, then ...fine by me.

........oztules
Village idiot...or... just another hack out of his depth
 
fillm

Guru

Joined: 10/02/2007
Location: Australia
Posts: 730
Posted: 02:12am 16 Oct 2009
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Hi Glenn , where did you put the caps page ,I looked on the main page but couldn't find it ...
PhillM ...Oz Wind Engineering..Wind Turbine Kits 500W - 5000W ~ F&P Dual Kits ~ GOE222Blades- Voltage Control Parts ------- Tower kits
 
Gizmo

Admin Group

Joined: 05/06/2004
Location: Australia
Posts: 5019
Posted: 02:24am 16 Oct 2009
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Its on the Contents page, in the eletronics section. I didnt want to put a link on the front page until the forum comunity have given it the once over, and I wanted the new pedal generator from Dave to get a few more days in the spotlight.

Glenn
The best time to plant a tree was twenty years ago, the second best time is right now.
JAQ
 
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