Overheating regulator...

Post by **CronoTriggerfan** » Mon Sep 25, 2006 4:17 pm

Okay, my homemade 7808 is getting too hot. I put on the largest heatsink I could; after it still got too hot, I backed it with some metal heat shielding. It helped, but still too hot. I don't have room in my case for a fan, although I know that would be the best solution. However, the hot glue around the heatsink remains normal temperature, and at max heat, it's just a bit warm. Could I just cover the entire thing with hot glue, or would this damage the regulator at all? Thanks!

CTFan

Post by **bicostp** » Mon Sep 25, 2006 4:24 pm

If it's getting excessively hot, you don't want to insulate it further.

How much of a load are you applying to it? The little thing might not be able to handle it...

You could cool it using a heat sink, but a fan may not be needed. If you create a duct, and use it to connect the heat sink and vents on the top and bottom of the portable, convection will cool it a bit when you hold the unit upright. (Convection simply works on the "hot air rises" principle. It's how the first Macs and the CRT iMacs were cooled.)

Post by **CronoTriggerfan** » Mon Sep 25, 2006 4:33 pm

Well it's inputting 12v; is that too much?

Thanks, I'll give the convection method a try, and add some more heatsink backing. Other than that, though, do I have any more options?

CTFan

G-force · Post by **G-force** » Mon Sep 25, 2006 4:57 pm

Do you have a capacitor on the input? I missed one once on a NESP, and that led to it heating up and under-voltage output.

Post by **CronoTriggerfan** » Mon Sep 25, 2006 5:08 pm

G-force wrote:Do you have a capacitor on the input? I missed one once on a NESP, and that led to it heating up and under-voltage output.

Hmmm...Nope, unless there's one on the GC power line. Is there? I'm getting the 8 standard volts from the 7808, so I don't have any under-voltage issues.

CTFan

Turbo Tax 1.0 · Post by **Turbo Tax 1.0** » Mon Sep 25, 2006 5:32 pm

your not putting a fan in your GCp, the fan isnt neccassary i guess but i would say its a good idea to put one in, the same thing was happening with my 7808 i just threw it next to the fan and i didnt have any more problems.

the GC heat sink also tends to get pretty hot.

daguuy · Post by **daguuy** » Mon Sep 25, 2006 6:18 pm

are linear regulators the only ones that you can change the voltage? if not, you could add 2 resistors to a switching regulator because those don't get as hot

Nucklez · Post by **Nucklez** » Mon Oct 02, 2006 8:50 pm

You can run two 7808's in parallel. They are rated at 1 AMP each, so two in parallel would be rated at 2 AMPs. You can simply bridge the Vin and Grounds, then put diodes on each Vout to keep them from from burning up. The heat is probably coming from the load that you have on Vout instead of how much voltage is being dropped across the 7808. To prove that, run the circut with just a voltmeter connected to Vout, I would be willing to bet it doesn't get that hot. I have a circuit dropping 12v to 3.3v using LM317 Voltage Regulators, and the regulators don't get the slightest bit hot without a heafty load.

*Edit*
I saw the post on what you mean by "Homemade 7808" in another post. To run that in parallel you would need to bridge Vin, duplicate the resistors on each Ground/Vout on both regulators, then use the diodes to connect the Vouts. Sound fun? If you need a schematic let me know and I'll write one up for ya'!

Retromaster · Post by **Retromaster** » Sat Nov 25, 2006 6:35 pm

go to radio shack and buy several tubes of silicon heatsink lubricant and
glob it on the heatsink. stick a tube in your pocket and take it with your portable, and if it gets hot, blow it repeatedly and replace lubricant.

atari2600a · Post by **atari2600a** » Sat Nov 25, 2006 7:52 pm

Dude, this thread is over 2 months old...

Retromaster · Post by **Retromaster** » Sat Nov 25, 2006 8:05 pm

I didn't know that. I thought he would come back.

Retromaster · Post by **Retromaster** » Sun Dec 03, 2006 5:46 am

look, A2600, sometimes people like their posts and they're proud of them.........................................SO THEY COME BACK WHEN THERE'S A NEW POST.

Post by **CronoTriggerfan** » Sun Dec 03, 2006 10:18 am

Still, you don't bump old topics. Besides, I already fixed this problem with extra heatsink backing. Thanks anyways, I guess.

Could someone please lock this now?

CTFan

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