Regulator footprint?

[matta]

Hi Guys,

I am wanting to buy some regulators for one of Fabio's PSU's.
But now the issue is I can get LM317 in both TO-220 and TO-92, which
one do I get? Or can I use either? How do you know which of those 2
packages to use?

Thanks

Matt

 

[alk509]

Electrically they're the same of course (except for maybe lower power dissipation on the '92). Do you have the board with you? or a picture of it? It should be obvious which one to use by looking at the PCB footprint.

Peace,
Al.

 

[alk509]

It just occured to me that maybe you don't know what TO-92 and TO-220 look like... Is that what you're asking? If so, you can download the datasheet for the device and they usually have mechanical drawings of the available packages.

Peace,
Al.

 

[matta]

Thanks Alk :thumb:

That cleared it up, I need TO 220, it is for a PSU and looking at what other people have stuffed them with that is what I need. Also the schemo shows pins 123 not CBE.

Here is a pic of the board:

I did try get the Datasheet off Alldatasheet.com, but my connection was VERY slow... got to love Africa.

Thanks again

Matt

 

[alk509]

[quote author="matta"]Also the schemo shows pins 123 not CBE.[/quote]

Actually, the pins on a TO-92 are also numbered "1 2 3"... The image I linked to must be for a specific transistor in a TO-92 package (C = Collector, B = Base, E = Emitter).

But don't worry about that, looking at the PCB, you definitely want a TO-220 regulator. :thumb:

Peace,
Al.

 

[Greg]

I built up one of Fabio's PSUs with a few slighly different components last night for a pair of Neve 1272s... as alk said, TO-220 is what you need. I bought a couple extra of these from Fabio. These are great little PSUs !!!

Are you using this for an API?

PS - Your THAT 2180LBs are on their way !!!

 

[matta]

Hey Greg,

Thanks for the info. I have always used TO-220 for all the PSU's I've made in the past (which ain't many, 3 to be exact), but when confronted with the TO-92 option I paniced

I was dealing with a parts store on the phone and they asked which option and it threw me since I only knew of the TO-220 package in the LM317.

Alk, thanks for pointing for the BCE was not related to the Reg TO-92 package, I can clearly see it is a transitor (A BC184 to be exact), I was stupid enough to miss it first time around.

Back to the PSU, I am hoping it will be for a pair of Fabio's API's, I have the boards which I will slowly stuff as and when I can, get both time and money

I have just wrapped up my 'channel strip' with 2 Greens and a Calrec, the rack looks very Ghetto DIY, I'll post some pics in a few days but It sounds great though :thumb:

Thanks for the news on the THAT's! I have pretty much bought 80% of the parts already, and while I was ordering the regs for them from your list I ordered a few regs for the PSU as well.

Cheers

Matt

 

[pstamler]

If you still need the datasheet, go to http://rocky.digikey.com/scripts/ProductInfo.dll?Site=US&V=14&M=LM317T and click on the lower link, the one that says "LM117/LM317".

In general, a good way to find datasheeets is to go to www.digikey.com and do a search for the product. When the hit screen comes up, click on the version of the part you want, then click on the link for "Technical/Catalog Information" which is farther down on the screen, below the price info. Digi-Key doesn't carry everything by a long shot, but they have good datasheet links for the semiconductors and passive parts they do carry.

Peace,
Paul

 

[Greg]

hey Matt:

Check out this thread if you're going to be building a Bauman PSU. There are a couple simple mods that will make this PSU perform better.

http://www.groupdiy.com/index.php?topic=5282&highlight=bauman+psu

The main thing, if you look at the schematic, is the 5VDC will load down the phantom supply (and create alot of heat), so it's a good idea to take R10 from the R1/C1 junction.

 

[PRR]

> confronted with the TO-92 option I paniced

TO-92 pack is good for maybe 0.3 Watts of heat.

TO-220 is good for 20 Watts (if clamped to a silver bar in a cool lake).

Regulator Watts are the Current times the Wasted-Voltage.

So if you start with 8V and regulate to 5V, and only have a 10 milliAmp load, you need (8-5)*0.010= 0.030 Watts. TO-92 is ample and smaller and cheaper. If you just have a couple chip opamps, a couple TO-92 is probably ample.

But if you start with 25V and regulate to 15V at 100mA, (25-15)*0.1= 1 Watt. A TO-92 will melt (actually these regulators just shut-down). You need the TO-220, and probably a heatsink.

A naked TO-220 "will" dissipate 1 Watt, and I've seen it done commercially, but it runs way too hot for my taste. So I'd add a couple square inches of sheet-metal. Above 3 or 4 Watts you need a Real Heat Sink, generally an aluminum extrusion (though you can get "9Watt" stamped/bent sinks that I would put 5W into).

I bet you can get these regs in SMT. With proper PCB copper-foil area, dissipation can be similar to TO-92, maybe better. But most DIYers don't do SMT.

 

[matta]

PRR,

Concise as always! Many thanks :thumb:

Thank goodness I didn?t buy the the TO-92 and try it, though it sounds like
it will just shut down under over load as opposed to ?releasing smoke?.

It reminds me of a funny blooper with regards to ?releasing the smoke?.

I was working on a pilot light for my rack and had a neon that could be
connected to 220V AC and an standard LED for low V DC connection, they had
the same package/casing and I grabbed the wrong one and connected the
LED to 220V AC.... lets just say if you ever want to see and hear a pop and
smoke... try it... It took around 3 days to clear the smell out of my
workshop...

Greg thanks for the info on the Bauman thread, I checked it out and it made
for a good read.

Cheers

Matt

 

[PRR]

> it sounds like it will just shut down under over load as opposed to ?releasing smoke?.

These regulators are pretty smoke-tight except for over-voltage and reverse-voltage. (There used to be UN-protected regulators like the LM100/105 and 723, but they went out of fashion pretty quick when protected regulators appeared.)

If you are ever in a situation where you can get "the same transistor" in TO-92 or TO-220, remember that transistors are happy to smoke. For several reasons, you never find the exact-same transistor die in -92 and -220 cases, but when you start cross-referencing to find something in-stock be sure to watch the case option.