Well I had to see what was going on inside one of my Bad LM 338K chips. So I cracked one open. Has Anyone seen what the inside of a real one of these things look like? I mean HOW THE !!!! not sure how this thing will look in the system here, if others can see the picture clear. However HOW can this take a 5amp load? This blew with little more then 1,04amps This is BS and a bad chip Or is this really how this is made?

I can see why this failed that very small wire is broke in 2 No way can I see this taking very much current!...

James

 

Probably a counterfeit.

Where did you purchase? Any package irregularities such as scrapes, easily removed markings, etc?

Real parts have over current and temperature protection so they should be able to handle some abuse.

 

Well yeah that is what I had figured. Within the last month I have bought from a few different places a few in USA (Found to be selling crap china fakes) and a few places in China thinking I would get lucky and get someone that is selling real chips. However all off ebay for lack of knowing somewhere that I don't need to spend loads of money do to minimum. buying requirements. All I was doing was testing for normal use. Like others that I have found over the internet as fake these can't do 1amp without fail

Oh well still on my quest for good chips. I do have a good power supply or for the one I like more then any is a Boost/Buck converter. It is a China made unit by MingHe and very happy with it so far. 0 to 38v so it covers everything that I am doing now days and upto 6amps and I have tested it up to 5 so far. So not everything from China is junk.

Now I see that what I have paid in these I could have got a good one that wouldn't fail. So now I guess I will just fork out the 54 usd to Digi-Key to get a real one. Then my quest ends lol. National and Ti the same.

 

So now I guess I will just fork out the 54 usd to Digi-Key to get a real one.

Jameco.com has them for $10.
http://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?search_type=jamecoall&catalogId=10001&freeText=LM338k&langId=-1&productId=23835&storeId=10001&ddkey=http:StoreCatalogDrillDownView

Another option is to use LM317T with an external pass transistor.

 

Well that seems like a place I will buy from first then seeing 10 for one of these is far better then 54 lol. Thank you

About the LM317T I am not sure that it would be as good for what I like to do. 1.5 to 2.2 amps isn't much current for some of the things that I like to mess around with. It is on my todo list of buying a few and making something off the TO220 package. Don't have as much time as I used to these days for my Personal Hobbies.

Thank you for the link and heads up on a place to check out.

James

 

About the LM317T I am not sure that it would be as good for what I like to do. 1.5 to 2.2 amps isn't much current for some of the things that I like to mess around with.

With an external pass transistor as I suggested, you can get far more than 5A. The datasheet shows a circuit, including one with multiple integrated transistors (LM195) in parallel.

You just need to make sure you divide the current in a way that allows the LM317 to protect the external pass transistors while it's protecting itself. External pass transistor(s) need to be mounted on the same heatsink for best protection.

Digikey has a wide selection of parts, but low price isn't a selling point. Jameco will price match if you happen to find a lower price that they can verify.

 

Oh very nice. I guess I need to look over the Datasheet it has been a little while in my mind it only could remember that I had seen back then as stated before.. So I never really went over the examples of things thinking it was to low for my needs. I did see it said 1.5 and above so then in little ways down it said 2.2 so I was like wow not much but then your post now explains the above as being something even higher.

Thank you again for the Jameco info.

James