Bob there were some treads about the TO-3 5V regulators about a year ago here. In the past the used market was flooded with” Chinese knockoff’s”. The voltages were all over the map. I always test them these days before inserting into a board. Within about 5% of V into a flash lamp bulb being my cutoff. Jameco sells the LM323K’s (5V,3A) for$ 4.75, #23667. They sell the 7895K’s (5V 1A) for $2.49. I actually like the 78H05’s I get from Anchor Electronics (www.anchor-electronics.com ), $2.95. Never had a problem with them.
The reason I use these (old) TO-3 regulators is they seem to have much better heat dissipation, particular when you go above 1A in comparison to the TO-220’s where at 1.5A’s you can burn your finger! Tom Lafleur was kind enough to make me up a small circuit board using a LM22677 modern day switching 5V regulator – thanks Tom. It contains a few components besides the regulator but runs almost cold. I intend to try and incorporate a circuit like this on later high ampage S100 boards, but for ease of use, it’s hard to beat those old TO-3’s. John From: [email protected] [mailto:[email protected]] On Behalf Of Bob Bell Sent: Tuesday, February 24, 2015 2:58 PM To: [email protected] Subject: RE: [N8VEM-S100:6439] Discussion About Filter Capacitors 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: [email protected] [mailto:[email protected]] On Behalf Of Crusty OMO Sent: Monday, February 23, 2015 11:25 PM To: [email protected] 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: <mailto:[email protected]> [email protected] To: <mailto:[email protected]> [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: <mailto:[email protected]> [email protected] [ <mailto:[email protected]> mailto:[email protected]] On Behalf Of Crusty OMO Sent: Monday, February 23, 2015 12:36 PM To: <mailto:[email protected]> [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: <mailto:[email protected]> [email protected] > To: <mailto:[email protected]> [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 <mailto:[email protected]> > [email protected]. > For more options, visit <https://groups.google.com/d/optout> > 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 <mailto:[email protected]> [email protected]. For more options, visit <https://groups.google.com/d/optout> 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 <mailto:[email protected]> [email protected]. For more options, visit <https://groups.google.com/d/optout> 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]. 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