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Total 23 documents matching your query.

1. [TenTec] Is there a beefier 2N5301? (score: 1): Author: "Bill Acito W1PA" <w1pa@hotmail.com>; Date: Tue, 6 Mar 2007 15:55:43 -0500; Is there a "beefier" replacement for the single pass transistor on the back of the 252 supply? 2N5301; NPN, 40V 30A 200W I have to replace it every few years (good thing for crowbars), and was wonder; /archives//html/TenTec/2007-03/msg00120.html (6,805 bytes)
2. Re: [TenTec] Is there a beefier 2N5301? (score: 1): Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>; Date: Tue, 06 Mar 2007 15:24:21 -0600; I've used 2N5302 for a bit more voltage head room. Dissipation is likely limited by the power supply heat sink. Be sure to apply a minimum amount of heat sink grease to the replacement transistor and; /archives//html/TenTec/2007-03/msg00121.html (9,252 bytes)
3. Re: [TenTec] Is there a beefier 2N5301? (score: 1): Author: "Bill Acito W1PA" <w1pa@hotmail.com>; Date: Tue, 6 Mar 2007 17:34:34 -0500; Jerry, Could I just swap in a darlington pair like the 2N5686 (80V, 50A) and loaf along at my 18A, and be that much further inside the max current limit (and less likely to fail?) http://www.onsemi.c; /archives//html/TenTec/2007-03/msg00124.html (7,553 bytes)
4. Re: [TenTec] Is there a beefier 2N5301? (score: 1): Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>; Date: Tue, 06 Mar 2007 16:59:37 -0600; That depends on circuit details. The Darlington will have a great deal more current gain but at the cost of at least twice the base to emitter voltage when forward biased. And it will have quite a bi; /archives//html/TenTec/2007-03/msg00126.html (10,695 bytes)
5. Re: [TenTec] Is there a beefier 2N5301? (score: 1): Author: "Gary Hoffman" <ghoffman@spacetech.com>; Date: Tue, 6 Mar 2007 18:59:02 -0500; Active cooling might well be an answer. Not just a fan, but how about a TEC device ? If there were wide enough interest I could perhaps offer a design as this sort of thing is what I do (thermodynami; /archives//html/TenTec/2007-03/msg00128.html (9,350 bytes)
6. Re: [TenTec] Is there a beefier 2N5301? (score: 1): Author: "Gary Hoffman" <ghoffman@spacetech.com>; Date: Tue, 6 Mar 2007 19:07:06 -0500; a That is where a TEC design would come into play. You can keep that heatsink just as cold as you want. 73 de Gary, AA2IZ _______________________________________________ TenTec mailing list TenTec@c; /archives//html/TenTec/2007-03/msg00131.html (8,875 bytes)
7. Re: [TenTec] Is there a beefier 2N5301? (score: 1): Author: Shawn Upton <kb1ckt@yahoo.com>; Date: Tue, 6 Mar 2007 16:15:43 -0800 (PST); What's wrong with a fan, or a couple of small ones? The cheap PC ones won't last long, but should do alot for continous duty heat dissapation. Responding to an earlier post: it's better to use too li; /archives//html/TenTec/2007-03/msg00132.html (9,197 bytes)
8. Re: [TenTec] Is there a beefier 2N5301? (score: 1): Author: "Bill Acito" <w1pa@hotmail.com>; Date: Tue, 06 Mar 2007 19:32:47 -0500; Jerry, So what causes the pass transistor to fail? (my crowbar is after the pass, in the cable... added after the first fail took out half the IC's on my Omni back in 1980 (under warranty, thankfully; /archives//html/TenTec/2007-03/msg00133.html (8,716 bytes)
9. Re: [TenTec] Is there a beefier 2N5301? (score: 1): Author: "Gary Hoffman" <ghoffman@spacetech.com>; Date: Tue, 6 Mar 2007 19:50:20 -0500; It is interesting that most of us don't know how important the heat sink goop is, and how much of the heat transfer takes place through it. The two metal surfaces (heat sink and transistor) even if m; /archives//html/TenTec/2007-03/msg00134.html (11,692 bytes)
10. Re: [TenTec] Is there a beefier 2N5301? (score: 1): Author: "Denton" <denton@oregontrail.net>; Date: Tue, 6 Mar 2007 17:01:05 -0800; Begs the question....why is the crowbar's clamp typically put across the output of a power supply instead of across the filter cap? The crowbar's sence connection, of course, belongs at the power sup; /archives//html/TenTec/2007-03/msg00136.html (10,381 bytes)
11. Re: [TenTec] Is there a beefier 2N5301? (score: 1): Author: "Ralph" <w8bvh@sbcglobal.net>; Date: Tue, 6 Mar 2007 20:05:14 -0500; Gary: I've been reading this thread with some interest but I don't know what "TEC" is. Can you explain to me?? Thanks for the help. Ralph Howes W8BVH _______________________________________________ T; /archives//html/TenTec/2007-03/msg00137.html (9,323 bytes)
12. Re: [TenTec] Is there a beefier 2N5301? (score: 1): Author: Duane - N9DG <n9dg@yahoo.com>; Date: Tue, 6 Mar 2007 17:07:56 -0800 (PST); Because in many cases it is the pass transistor itself failing (shorted) that is the failure mode which causes the overvoltage to appear on the output lead. Regulator failures from what I can tell ar; /archives//html/TenTec/2007-03/msg00138.html (9,143 bytes)
13. Re: [TenTec] Is there a beefier 2N5301? (score: 1): Author: Ralph Matheny <mathenyr@marietta.edu>; Date: Tue, 6 Mar 2007 20:25:53 -0500 (EST); I'd pose the question "what is really triping the crowbar?" If this is a repeated problem, perhaps the OVP circuit is getting some RF or a ground loop from the AC green wire which is causing the rath; /archives//html/TenTec/2007-03/msg00140.html (9,417 bytes)
14. Re: [TenTec] Is there a beefier 2N5301? (score: 1): Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>; Date: Tue, 06 Mar 2007 19:50:34 -0600; There may be more efficient and economical techniques. Such as low drop regulators using MOSFETs or going to switching supplies. Wouldn't moving 100 watts average from a pass transistor require more; /archives//html/TenTec/2007-03/msg00144.html (10,155 bytes)
15. Re: [TenTec] Is there a beefier 2N5301? (score: 1): Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>; Date: Tue, 06 Mar 2007 20:28:08 -0600; The pass transistor failing is the desired reason for tripping the crowbar. Often the crowbar is sensitive to RF, sometimes the regulator is sensitive to RF. One time I built out a regulator with a c; /archives//html/TenTec/2007-03/msg00146.html (14,074 bytes)
16. Re: [TenTec] Is there a beefier 2N5301? (score: 1): Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>; Date: Tue, 06 Mar 2007 20:30:55 -0600; So today in Iowa that heat sink could be cooled to 15 F but on a warm summer day in Houston, the dew point might be 95 F so you would have to include a dew point sensor to pick the cooling point, or; /archives//html/TenTec/2007-03/msg00147.html (11,523 bytes)
17. Re: [TenTec] Is there a beefier 2N5301? (score: 1): Author: "Gary Hoffman" <ghoffman@spacetech.com>; Date: Tue, 6 Mar 2007 22:47:19 -0500; I'm sorry Ralph....I speak in techno-babble all too often ! A TEC is a thermoelectric cooler. As you probably know, if you apply low voltage DC to one of these babies, it pumps heat - making one side; /archives//html/TenTec/2007-03/msg00148.html (10,669 bytes)
18. Re: [TenTec] Is there a beefier 2N5301? (score: 1): Author: "Gary Hoffman" <ghoffman@spacetech.com>; Date: Tue, 6 Mar 2007 23:35:39 -0500; Hi Jerry, Nope...a properly designed TEC cooler is very efficient. My designs usually operate at a COP of between 3 and 7. Its a common myth that TEC coolers operate at a COP of near unity or less. (; /archives//html/TenTec/2007-03/msg00149.html (11,750 bytes)
19. Re: [TenTec] Is there a beefier 2N5301? (score: 1): Author: "Gary Hoffman" <ghoffman@spacetech.com>; Date: Tue, 6 Mar 2007 23:43:34 -0500; That's right Jerry....and common practice. But better practice is to seal against moisture, which is what I do. Its not as though there is very much moisture, nor is there any water pressure. points.; /archives//html/TenTec/2007-03/msg00151.html (12,708 bytes)
20. Re: [TenTec] Is there a beefier 2N5301? (score: 1): Author: "Gary Hoffman" <ghoffman@spacetech.com>; Date: Tue, 6 Mar 2007 23:45:42 -0500; A further comment is that many TEC coolers are used in fact as dehumidifiers. As such, they are available from the factory sealed against water. You must take further steps of course. But it is not s; /archives//html/TenTec/2007-03/msg00152.html (12,770 bytes)

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