300W Resistive load?
in [Design]
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From: Nico Coesel on 18 Jul 2010 04:40 Hammy <spam(a)spam.com> wrote: >What is something cheap and simple that can be used to dissapate 300W >on a 200Vdc bus. I'm trying to think of something I could maybe pick >up at a local homedepot or similiar. > >I need a 300W load to test out my PFC. I've constructed an adjustable dummy load by using 4 TO3 transistors from an old switching power supply. A heatsink and a couple of fans take care of the heat. The whole thing isn't much larger than a shoe box. -- Failure does not prove something is impossible, failure simply indicates you are not using the right tools... nico(a)nctdevpuntnl (punt=.) --------------------------------------------------------------
From: Tim Williams on 18 Jul 2010 07:25 "Nico Coesel" <nico(a)puntnl.niks> wrote in message news:4c42bd4b.224380781(a)news.planet.nl... >>What is something cheap and simple that can be used to dissapate 300W >>on a 200Vdc bus. I'm trying to think of something I could maybe pick ^^^^^^ >>up at a local homedepot or similiar. >> >>I need a 300W load to test out my PFC. > > I've constructed an adjustable dummy load by using 4 TO3 transistors > from an old switching power supply. A heatsink and a couple of fans > take care of the heat. The whole thing isn't much larger than a shoe > box. Doesn't work in this case though, you'll be in the second breakdown region. Unless it was slightly less old and used TO-3 MOSFETs, which Idunno, might be worth something on eBay. :^) Hammy might have a few FETs left over from the boost though, they would handle the voltage just fine, as long as there's enough for the power. Tim -- Deep Friar: a very philosophical monk. Website: http://webpages.charter.net/dawill/tmoranwms
From: Hammy on 18 Jul 2010 08:05 On Sun, 18 Jul 2010 06:25:40 -0500, "Tim Williams" <tmoranwms(a)charter.net> wrote: >"Nico Coesel" <nico(a)puntnl.niks> wrote in message news:4c42bd4b.224380781(a)news.planet.nl... >>>What is something cheap and simple that can be used to dissapate 300W >>>on a 200Vdc bus. I'm trying to think of something I could maybe pick > ^^^^^^ >>>up at a local homedepot or similiar. >>> >>>I need a 300W load to test out my PFC. >> >> I've constructed an adjustable dummy load by using 4 TO3 transistors >> from an old switching power supply. A heatsink and a couple of fans >> take care of the heat. The whole thing isn't much larger than a shoe >> box. > >Doesn't work in this case though, you'll be in the second breakdown region. Unless it was slightly less old and used TO-3 MOSFETs, which Idunno, might be worth something on eBay. :^) > >Hammy might have a few FETs left over from the boost though, they would handle the voltage just fine, as long as there's enough for the power. > >Tim FETS I have a lot of. I also have some nice(2) brick heatsinks I scavenged from some old microwave oven and car stero ampslifier. Thta was my original thought but I was thinking it would take to many to dissapate the power 275W. The biggest I have in quantity is the FQA24N50 TO-3PN http://www.fairchildsemi.com/ds/FQ/FQA24N50.pdf I have about 30 of those. Actually those are in a pretty beefy package maybe 5 on a brick with a fan might work. I also have about 40 of these FQP27N25 TO-220 http://www.fairchildsemi.com/ds/FQ/FQP27N25.pdf Both of those Newark had on for dirt cheap and I was buying ten of each everytime I did an order. Figured they might come in handy at some time.;-) I have 1 or 2 IRF350 in to-3 no suitable heatsink for that power level.
From: Joerg on 18 Jul 2010 08:30 Paul Hovnanian P.E. wrote: > Joerg wrote: >> Hammy wrote: >>> On Sat, 17 Jul 2010 07:00:35 -0700, Joerg <invalid(a)invalid.invalid> >>> wrote: >>> >>>> Hammy wrote: >>>>> What is something cheap and simple that can be used to dissapate 300W >>>>> on a 200Vdc bus. I'm trying to think of something I could maybe pick >>>>> up at a local homedepot or similiar. >>>>> >>>>> I need a 300W load to test out my PFC. >>>> Light bulbs? Two in series and then as many of those in parallel as needed. >>> Sounds good one 60W bulb is about 200 ohms. ... >> At 200V each bulb gets only 100V so the resistance will be a little >> lower. You could measure that if it must be precise. >> >>> ... I'll look around for some small cheap bulb mounts. >> You can also solder to them. If careful they can later still be used for >> their intended purpose. But make sure you place them onto a heat >> resistant surface during the test :-) > > Ceramic lamp sockets are cheap and available at any hardware store. And > they are UL listed and approved for the purpose. No need to hack > soething for which an easy solution exists. > Ceramic sockets usually cost several times the price of a bulb: http://www.acehardwareoutlet.com/productdetails.aspx?sku=32508&source=GoogleBase >> Good news is you may not even have to drive all the way to Home Depot. >> Supermarkets also have a variety of them. Of course, then your wife >> might hand you a lengthy "while you are there anyhow" list and you don't >> get to look at all the new power tools, barbecues and stuff. Man's toy >> store ... > > Just take every other bulb out of the bathroom fixture. And if the wifes > makeup looks a bit funny afterwards, just keep your mouth shut. > Oh, that'll get you several slaps with the handbag next time she looks into a mirror :-) -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: Jim Thompson on 18 Jul 2010 11:28
On Sun, 18 Jul 2010 08:05:57 -0400, Hammy <spam(a)spam.com> wrote: >On Sun, 18 Jul 2010 06:25:40 -0500, "Tim Williams" ><tmoranwms(a)charter.net> wrote: > >>"Nico Coesel" <nico(a)puntnl.niks> wrote in message news:4c42bd4b.224380781(a)news.planet.nl... >>>>What is something cheap and simple that can be used to dissapate 300W >>>>on a 200Vdc bus. I'm trying to think of something I could maybe pick >> ^^^^^^ >>>>up at a local homedepot or similiar. >>>> >>>>I need a 300W load to test out my PFC. >>> >>> I've constructed an adjustable dummy load by using 4 TO3 transistors >>> from an old switching power supply. A heatsink and a couple of fans >>> take care of the heat. The whole thing isn't much larger than a shoe >>> box. >> >>Doesn't work in this case though, you'll be in the second breakdown region. Unless it was slightly less old and used TO-3 MOSFETs, which Idunno, might be worth something on eBay. :^) >> >>Hammy might have a few FETs left over from the boost though, they would handle the voltage just fine, as long as there's enough for the power. >> >>Tim >FETS I have a lot of. I also have some nice(2) brick heatsinks I >scavenged from some old microwave oven and car stero ampslifier. > >Thta was my original thought but I was thinking it would take to many >to dissapate the power 275W. > >The biggest I have in quantity is the FQA24N50 TO-3PN > >http://www.fairchildsemi.com/ds/FQ/FQA24N50.pdf > >I have about 30 of those. > > Actually those are in a pretty beefy package maybe 5 on a brick with >a fan might work. > > >I also have about 40 of these FQP27N25 TO-220 > >http://www.fairchildsemi.com/ds/FQ/FQP27N25.pdf > >Both of those Newark had on for dirt cheap and I was buying ten of >each everytime I did an order. Figured they might come in handy at >some time.;-) > >I have 1 or 2 IRF350 in to-3 no suitable heatsink for that power >level. Finned heat sinks, arranged as a square tunnel, fins inward, file, mill, whatever so they fit together nicely, and the "square" is muffin-fan size... which fits on one end. ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | Friday is Wine and Cheeseburger Day |