Hey, I have the 1984 version of the IC Master. There’s absolutely no memory of where I got the LM309K. Maybe it was bad from the start. That shorted LM309K was the only one I ever had. I never knew it would be that expensive! And I don’t know of any advantage of it over the 7805. There’s also an LM323K – I know that’s expensive. It’s rated for 3 Amps. Bob Bell From: n8vem...@googlegroups.com [mailto:n8vem...@googlegroups.com] On Behalf Of Crusty OMO
Sent: Monday, February 23, 2015 11:25 PM
To: n8vem...@googlegroups.com
Subject: RE: [N8VEM-S100:6431] Discussion About Filter Capacitors Hi Bob,
That's about the only one I ever heard of... and might be because of it's early age!?
Speaking of rarities... I once found a 1N914 diode that was marked wrong! I kept it for a year then tossed it out... silly me.
I'm sure the rarity of it would make that diode worth a whole dollar on the ebay market! LoL
So, what's the deal between 309's and 7805's? I'm thinking it's a manufacturer part numbering scheme... worth a minute to research in my IC MASTER 1982.
Let's see... makers of the 309 chip are:
Fairchild
Motorola
National
Silicon G
Siliconix
Makers of 7805
Fairchild
Motorola
National
NEC
SGS
Silicon G
TI
I suppose it doesn't mean much, if Fairchild dropped the 309 and replaced it with the 7805... I just wouldn't see the dates...
I'm looking up Digikey, they sell LM309K's (for $37.20 ouch!) from TI.
I guess the next logical place to check the differences would be in the data sheet... but it's too late at night now to do this... and my curiosity is going.
Cheers,
Josh
From: bbel...@gmail.com
To: n8vem...@googlegroups.com
Subject: RE: [N8VEM-S100:6426] Discussion About Filter Capacitors
Date: Mon, 23 Feb 2015 18:44:37 -0500 Yes, that would be the situation for a complete board. However, I was incredibly lucky when I ran across the one shorted regulator I have ever seen. It was an old LM309K (precursor to the 78xx series, I think) in a TO-3 package. I was using it to build a bench power supply for prototyping. So, of course, after building it, I measured the output with a meter and found it to be the same as the input. What more is there to say? I replaced the regulator and moved on, never to see one shorted again. I guess I should have saved it for posterity! Bob Bell I doubt you would forget a shorted regulator... that would likely blow every chip on the board, or perhaps if there are many chips, the quick rise in current would take down the power supply? I have repaired boards that were hit by lightning... I recall needing to change nearly every chip... with only a few original chips working, I changed those too, just in case there was any kind of hidden damage. In hind sight, I think those type of boards should be scrapped. > Date: Mon, 23 Feb 2015 06:30:52 -0800
> From: gregor...@gmail.com
> To: n8vem...@googlegroups.com
> Subject: RE: [N8VEM-S100:6419] Discussion About Filter Capacitors
>
> I don't remember a shorted 7805, but I could have missed one through the years.
> Majority had no voltage (+5V) output, failed open.
>
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