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ghurd
Average Member
USA
546 Posts |
Posted - 05/09/2007 : 18:30:36
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It's pretty bullet proof. I have not been able to blow one up while trying, and no one else has either (yet).
Don't trust a light bulb if switching very often. I burned out a head light in under an hour.
Plus, bulbs have a considerable surge current when cold. The fet may not like that idea.
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gotwind
Forum Admin
United Kingdom
1564 Posts |
Posted - 05/09/2007 : 18:48:22
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Hi Glenn (Ghurd) and welcome.
b.t.w Glenn was the guy who put together the led page for me, much appreciated, must have taken a fair bit of time.
http://www.gotwind.org/images/Glenn_Hurd.jpg
Glenn,
What is the suggested method of dumping the excess power, if not a incandescent bulb?
Maybe you could include the details here on this thread on how we could order your kit from the U.S?
I'm sure you would get quite a few orders, mainly from th U.K so a shipping fee would also be useful.
Thanks
Ben.
The Futures Green - Getwind of it. |
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ll81
Junior Member
124 Posts |
Posted - 05/09/2007 : 19:37:30
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Agreed the simpler the circuit the less to go wrong and that looks like a good reliable circuit, for a couple of pennys extra for gate stoppers there is no reason not to use them IMO. As long as the FET gate has enough votlage to hard clamp on the device it's change to positive temperature coefficient at high currents will protect it and allow it to pass considerable current for a short duration.
I personally have found a good quality bulb will take alot of abuse, is it possible that the power supply you was using put out more current than the bulb could source resulting in an increase in voltage and therefore a dead bulb. However as you state it will blow eventually so ideally something that will last a long time is desired. Have you found any good alternatives, I would be interested to see what others use.
Great work there on the load dump BTW, allways good to see effort put into helping others.
woo-hoo |
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ghurd
Average Member
USA
546 Posts |
Posted - 05/09/2007 : 20:51:13
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Ben, shipping & handling looks like US$3 for up to 2 kits, world wide. Once it gets past a certain weight the shipping cost goes through the roof.
I like big resistors. Like the 250~300W type, but only putting 60~80W into them. Only cost about 2 to 3 times more than a head light. Remember to use a flyback diode.
Thanks Woo-hoo. Actually it was a fet test. The bulb was connected to a 330ah battery at about 12.9~13.0V. Probably running around 100Hz. It kind of looked like it was on a dimmer switch that someone was turning up and down fairly fast, didn't look like 100Hz.
The IRFZ44 stayed cool, open air, no heat sink, temp barely raised at all, maybe 10 over ambient.
All IIRC. It was quite a while ago.
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gotwind
Forum Admin
United Kingdom
1564 Posts |
 Posted - 05/09/2007 : 21:28:53
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Thanks Ghurd.
That shipping sounds very good, air mail I assume? looks like we will have to order individually here. Does this make life difficult for you Glenn i.e You sending maybe one or maybe many small packages separately overseas?
I am aware that you are awaiting a few components,and a suggested price of $12.50 was mentioned + $3 shipping - that is obviously $15.50 in total or £7.67 GBP in the U.K
This U.K/U.S low exchange rate is really good at the moment 
May I suggest to anyone interested we could paypal Glenn £10 ($20) per order to cover his paypal fees, set at about 50p ($1).
This is still a great price for a nice circuit suitable for the Ametek 30 and Treadmill motor projects >100w Max
Glenn.
Let me know what you think, and if you have a paypal account, what address any payments could be made to.
Maybe II81 can point us towards a suitable 250~300W resistor here in the U.K as the dumpload? oh and how we can connect the 'flyback diode'.
Cheers
Ben.
The Futures Green - Getwind of it. |
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ll81
Junior Member
124 Posts |
Posted - 06/09/2007 : 19:43:10
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Them resistors are a bit pricey. I have a 4ohm 400 watt dummy load I use for testing my amplifier projects that works well. It didn't cost alot to make and was made of 40x 0r1 10 watt power resitors soldered in series. 20 woulld make a good load dump for 100 watt turbine.
The flyback diode is connected between the Drain and Source terminals of the FET with it's Cathode to Drain and Anode to Source. This way it is forward biased until any back EMF causes a potentail of more than -0.6v across the FET and therefore shunting it away and protecting the device.
woo-hoo |
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ghurd
Average Member
USA
546 Posts |
Posted - 06/09/2007 : 21:08:57
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I got tired of spending what seemed like forever building dump load resistors that were, uh, crappy when I was done. The 100W are less stressful, about £32 for 10.
Ben, I didn't consider paypal fees. I'll have to look into that. The cost of the silly little bubble-ope is what irks me.
1st class mail goes on the plane right after some of the fancier mail. If the weight stays to 2 kits, it's just as fast as air mail, but a lot cheaper.
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gotwind
Forum Admin
United Kingdom
1564 Posts |
Posted - 06/09/2007 : 21:30:44
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Ok thats fine Glenn.
Please let us know when a fixed price is available.
I suspect there are at least 10 members that would be interested in receiving such a kit here.
No rush.
Ben.
The Futures Green - Getwind of it. |
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fungus
Moderator
311 Posts |
Posted - 07/09/2007 : 13:19:58
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I used to use 4 50w resistors in series for 2A (28w) dumping current, on a heatsink, could reconfigure for 100w... now I'm using a 150w ceramic car heater, can get them from maplin for £15.
I still have the old resistor panel if anyone wants it? Could chuck in the old 'ghurd controller' on perfboard.. Picture of it below in the top right:
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Edited by - fungus on 07/09/2007 13:21:02 |
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Del
Junior Member
United Kingdom
383 Posts |
Posted - 20/09/2007 : 20:14:10
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Hi Ghurd,
From the posts and conversations on the "solar panel" thread I see Mr Ben now has one of your dump load circuits. Are you now ready to make these generally available to all of us and if so what's the price. I seem to recall ben suggested £10 ($20) and that would cover your costs inc those naughty paypal fees. Just let me know and I'll order a couple from you.
Cheers
Del. |
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ghurd
Average Member
USA
546 Posts |
Posted - 20/09/2007 : 23:23:42
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Hi Del,
Ben received a pre-production "prototype" version of the kit.
All the parts should be there, but it is hard to say for certain. Things change.
The instructions still 100% totally suck. Most people didn't get any instructions at all and did fine building a working circuit.
The cost is US$12.50 for each kit, plus US$3 per order shipping and handling.
US$15.50 total for 1 kit. US$28 for 2 kits. 3 kits may cost more for S&H.
UK, Europe, Asia, etc, will receive instructions via email. (reduces the shipping costs)
PayPal is fine. I still do not know what they charge.
Honestly, I don't understand how these boards work.
Please do not expect me to see a reply to this message. I try.
I seem to be old and not very computer savvy. :-(
email to yahoo for ghurd1
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Del
Junior Member
United Kingdom
383 Posts |
Posted - 22/09/2007 : 11:51:53
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Hi Ghurd,
That sounds excellent. I'll send you a private message (you'll see it in the top right hand corner of the Gotwind page) to firm up the details.
Thanks again.
Del. |
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BushWhacker
Junior Member
Canada
359 Posts |
Posted - 23/09/2007 : 08:24:23
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Time for an electronically challenged question. Most of the above discussion went right over my head. By load dump are you talking about the components that redirects excess electricity to a component (light bulb or resistors) or the component it's self?
What I would like to use the excess electricity for is "free heat".
I propose using an automotive block heater installed in the side of a large cooking pot filled with water or antifreeze solution. I don't think that a block heater cares if the power supply is AC or DC, please correct me if I am wrong.
This heat supply would be set in a porch, fall through spring, and in a green house during late spring through summer. The part I don't understand is the electronics needed to detect when the batteries are fully charged and divert the excess electricity to the load dump (block heater in my example).
Please use little words as I have no background in electronics.
Cheers!
BW
Everything should be made as simple as possible, but not one bit simpler. - Albert Einstein |
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fungus
Moderator
311 Posts |
Posted - 23/09/2007 : 14:41:20
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| BushWhacker- a dumpload controller redirects electricity to another load such as a heater when the batteries are full; this is what ghurd's circuit does. An automotive heater block could be pretty good; although I wouldnt put it in water or antifreeze as I think they are conductive? Mineral oil like the stuff from oil filled heaters could be better to put it in I think as it isnt conductive and wont corrode the heater block with the electricity. |
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BushWhacker
Junior Member
Canada
359 Posts |
Posted - 23/09/2007 : 19:53:01
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Actually Fungus the block heater element is located in the "water jacket" of an engine and is submerged in coolant during normal operation. They usually last about 3000 hours of full power (500 to 1000 watt) use.
I guess you have to live in a colder climate to be exposed to these things. ;)
So I'll need a dump load controller, and then hook a load such as a block heater up to it. I think I've got it now, Thanks!
The reason I would like about 20 liters of coolant is the thermal mass will help regulate the rate that the porch/green house heats and cools.
Cheers!
BW
Everything should be made as simple as possible, but not one bit simpler. - Albert Einstein |
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The best load dump yet