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: [email protected] To: [email protected] 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 From: [email protected] [mailto:[email protected]] On Behalf Of Crusty OMO Sent: Monday, February 23, 2015 12:36 PM To: [email protected] Subject: RE: [N8VEM-S100:6421] Discussion About Filter Capacitors 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: [email protected] > To: [email protected] > 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. > > -- > You received this message because you are subscribed to the Google Groups > "N8VEM-S100" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > For more options, visit https://groups.google.com/d/optout.-- You received this message because you are subscribed to the Google Groups "N8VEM-S100" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout. -- You received this message because you are subscribed to the Google Groups "N8VEM-S100" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout. -- You received this message because you are subscribed to the Google Groups "N8VEM-S100" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
