Simple Shunt

[windstuffnow]

 Thanks dean...  Thats about as simple as it gets!   I'll give it a shot.

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[windstuffnow]

  Here is all I was trying to accomplish with this project... A complete, portable and small charging system for field and/or wind tunnel testing... I was sick of lugging around a battery, a spegetti pile of wires with clips and all the other misc to connect the rectifiers to the battery and turbine... Now I can connect the 3 AC output wires from the turbine and turn on the meters without all the rigging...

The picture above shows the output of the small 2x2ft Lenz in the wind tunnel at 15 mph.

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[Drives]

Ed:

For only an additional $1.97 plus tax you will like this even better.  (Sounds like a commercial)  The original schematic had a max limit of maybe 5 amps before the zener overheats (5 Watt zener).  You mentioned that all you were thinking of shunting was 3 amps.

This version uses another TIP3055 as the base control for the main shunt transistor.  The zener now only has to handle current for the base control transistor.  If heatsinked properly, and with a 12vdc cooling fan on the devices, you should be able to push it pretty hard.

You may want to play with different zener values to "dial" in exactly what you want.  

Keep up the good work on the Lenz 2, I am watching with great interest.

[Drives]

It looks like when I copied over my original diagram in my files, it changed the diagram in my first post to the one in my second post.  I should have saved it with a new name.

Ed:

Looks like a great set up!

[ruddycrazy]

Eh Ed,

     Ya might want to take a look at the 250 watt shunt regulator Oatley's sell as a kit. I made one up to suit my nife batteries and set it to swich at 16.5 volts. I'm using some heating wire as the dump load and the idea is to heat a tank of water with the dump load. By the way the shunt regulator is designed for either 12 or 24 volts but I changed a couple of resistors to get the right switch over point. By the way the dump load is controlled by 4 mosfets and with a heatsink they can handle 10 amps each so they claim. If you like I can take a pic of the regulator so you can see the setup but at $24 Oz for the kit it's a good buy.

Cheers Ruddy Crazy

[Opera House]

Need a cheap power resistor?  I was playing around with a slinky the other day and found it ot be a little over 2 ohms for the full length.  Make the center one common point and both ends another for a nice 20A load.

LM431 adjustable shunt regulators are available eBay (isn't everything) if you want to experiment.  There is one there with 5 regulators, pots and other stuff for 99 cents.

[windstuffnow]

  I looked at the ebay stuff, if they had a "buy now" option I probably would have gone for it.   I hate bidding on things and waiting 6 or more days... things change a lot in 6 days, god only knows what I'll be into by then !  

  I'd like to play with some LM431 circuits and will probably purchase a few somewhere soon.  For now the zener/transistor is doing a reasonable job ( hasn't smoked yet anyway ).  

.

[hvirtane]

Have you ever tried 'xfig'?

I'm not sure,

if it works well with windows,

http://www.cs.usask.ca/grads/wew036/latex/xfig.html

It is a free unix program

supplied with all GNU/linux systems.

- Hannu