Reply-To: "Martin Riddle"
From: "Martin Riddle"
References: <3D7B8B88.4ED5A338@bellatlantic.net> <3D7D580B.7DBE070D@bellatlantic.net> <3D7EB60D.B730482F@bellatlantic.net>
Subject: Re: Parallel LEDs calculation
X-Newsreader: Microsoft Outlook Express 6.00.2600.0000
Date: Wed, 11 Sep 2002 12:12:07 GMT
NNTP-Posting-Date: Wed, 11 Sep 2002 05:12:07 PDT
Organization: EarthLink Inc. -- http://www.EarthLink.net
wrote in message
> I see your numbers as a problem: how realistic do you
> think 112c is? That's 233f. How realistic is your 302f
> (150c)? Even the 85c - that's 185 f - you mentioned in
> your prior post is higher than what you'll ever find in
> the passenger compartment. To get the temperatures you
> mention, you'll have to get near the engine. Do you
> think he's going to mount these resistors on the exhaust
Sorry, your original post rolled off the news server.
But the auto enviroment is a harsh one. How hot does it get, I really dont
But if this is a high mount stop lite, then the chances of 'getting very
hot' is real. In an uncooled space that is being heated by thermal radiation
(the sun) it is quite possible for the temperature to reach the limit of the
So, using derating as a guide line a 1 w resistor would be the proper
choice. This makes a difference in reliability. Plus you dont want to pick a
resistor larger than you need, expecially if your making 100,000 units.
But for the hobbiest all this really dosent matter, there are mechanical
problems that are hard for the hobbiest to fix properly. And the device will
most likely fail after a year or two and get thrown out.
BTW, exhaust manifold temperatures run around 800f at WOT.