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: n8vem...@googlegroups.com [mailto:n8vem...@googlegroups.com] On Behalf Of Bob Bell 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 Hi Bob, From: bbel...@gmail.com 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: n8vem...@googlegroups.com [mailto:n8vem...@googlegroups.com] On Behalf Of Crusty OMO 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 --
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