{"id":4574,"date":"2012-10-11T07:23:42","date_gmt":"2012-10-11T14:23:42","guid":{"rendered":"http:\/\/rustybolt.info\/wordpress\/?p=4574"},"modified":"2012-10-16T08:27:44","modified_gmt":"2012-10-16T15:27:44","slug":"2012-10-11","status":"publish","type":"post","link":"https:\/\/rustybolt.info\/wordpress\/?p=4574","title":{"rendered":"2012-10-11 Finding An Equivalent Substitute Transistor"},"content":{"rendered":"

I came across this forum thread<\/a> where the person asks how to find and equivalent transistor.\u00a0\u00a0 First off I would like to say that if you substitute another transistor and it burns up in a few seconds, like it did in this case, then you should certainly consider that the circuit is bad in some other way and no matter how exact the replacement is, it is not going to work until the problem is fixed.<\/p>\n

I faced this ‘sub’ question many, many times years ago when I did a lot more TV and receiver and audio repair, and found out how important it was to get the right transistor. \u00a0 Someone gave me a good quality stereo amplifier, and said he didn’t want it anymore because he had it repaired but it sounded awful.\u00a0 I put the ‘scope on the output and I found that it was oscillating at 2 MHz!\u00a0 If I had put a hundred feet of wire on the output, I could have had a transmitter!<\/p>\n

I learned a lot about what the transistor datasheet is and how to use it.\u00a0 The manufacturers used to publish a data book, and they gave them away freely for just asking in a letter with you company name (a friend and I made up the company name Solid State Systems).\u00a0 So I got many transistor manuals and data books for every type of electronic component.<\/p>\n

Nowadays, much of the data cane be found online by googling for 2N3055 datasheet for example.\u00a0 You will get many hits for places that will let you download the datasheet .PDF for free, as long as you look at all their annoying adverts.<\/p>\n

But then what do you do with this datasheet?\u00a0 It’s full of technical jargon that the average person doesn’t understand.\u00a0 It took me years to learn enough about this to make a good judgment on what’s important to know in order to make a correct substitute.<\/p>\n

In this forum thread, people give all sorts of advice, from good to totally incorrect.\u00a0 I once told someone that his advice was, to be tactful, less than accurate, and you know what he told me?\u00a0 “The advice you get is worth exactly what you paid for it!\u00a0 $00.00!”\u00a0 And he was right.\u00a0 If you get free advice, you can expect that it’s worthless!<\/p>\n

But I try to give worthwhile advice.\u00a0 Not many care, though.\u00a0 They have no clue as to whose advice they should take.\u00a0 As a result they go wrong and are very often discouraged enough to throw the device out and go buy another new one.\u00a0 I think if more people would try to repair the broken equipment, it would save a lot of resources and the world would be a better place.\u00a0 But that’s a discussion for another time.<\/p>\n

Back to transistors.\u00a0 in the case I cited, he could get replacement 8050 transistors from Mouser<\/a> or Fairchild<\/a>, called the SS8050.\u00a0 They are very cheap, maybe a nickle apiece, even less in quantity.\u00a0 But the shipping might be many times the cost of the part.<\/p>\n

There is another part that might work.\u00a0 NTE sells replacement parts at ten or more times the cost from a distributor.\u00a0 They sell the NTE11, which is a very high current transistor, for about a dollar fifty.\u00a0 It’s in the same package as the 8050.\u00a0 But the gotcha is that the pinout is E C B instead of the 8050’s E B C – it’s the same as other similar Japanese transistors.\u00a0 So you will have to slip a short length of insulation (stripped off a solid wire) over the collector lead so you can cross it over without it shorting against one of the other leads.<\/p>\n

There are other substitutes, but those two are readily available.\u00a0 You can go to Radio Shack and buy some transistors from them, but the salesdroids don’t know any more about substitution than their customers, so buying a transistor from them is most likely hit-and-miss and a waste of time and money.<\/p>\n

\u00a0Substitution in Genera<\/strong>l – I have a few publications that are my favorite references when it comes to substitution.\u00a0 I used the National Transistor Databook so much that I wore it out, and had to get a replacement on eBay or Amazon<\/a>, I forget which.\u00a0 The great thing about this book is that it tells you which process the transistor came from.\u00a0 Then you can read about that process, find out what the chip looks like, and find which other transistors use the same process.\u00a0 For instance, you might find that the 2N4124 uses a certain process, and 2N3904 comes from the same process.\u00a0 So if the circuit demands are modest and the packages are the same, then one transistor could be substituted for the other.<\/p>\n

Motorola Transistor and Diode Manual<\/strong> – This tome (it’s 3 inches thick!) was the reference for just about any U.S. transistor or diode made up until its publication in 1969.\u00a0 This still covers a lot of the devices used today.\u00a0 After that there was not so much growth in the number of discrete devices (transistors, diodes, etc.) and more growth in integrated circuits.\u00a0 Today the number of transistors registered with the 1N and 2N numbers is still under ten thousand.\u00a0 There are other transistor makers that published transistor manuals and crossreference manuals, one was Sylvania, AKA ECG.<\/p>\n

NTE<\/strong> – Another way to get a rough idea of a substitute is to use the NTE catalog.\u00a0 You can also go online and search their web pages.\u00a0 Having the catalog on paper is easier and faster.\u00a0 There is one gotcha.\u00a0 I have done lookups in the NTE catalog, and they seem to think that the NTE123A or NTE123AP will substitute for just about any small transistor, when I know that they will clearly not substitute.\u00a0 But the catalog will give the reader a good idea of what package their substitute transistors are in, and what their rating are.\u00a0 For instance if the transistor is a power transistor, you can find the package and how much power, etc. it will handle.\u00a0 NTE sells a line of replacement transistors and parts, but their prices are very high.\u00a0 If you have an immediate need for a single part, then they may be a worthwhile solution.\u00a0 But I find that it’s much cheaper to buy a bag of a hundred transistors from Mouser, DigiKey, etc., for the price of one or a few NTE transistors.\u00a0 The NTE numbers are the same as the Sylvania ECG numbers, so NTE123AP is the same as ECG123AP.<\/p>\n

There was a lot of growth in the Japanese (2S numbers) and the Pro Electron (AC, BC, BD etc. numbers) series.\u00a0 These were used in a lot of\u00a0 the equipment manufactured in Japan, Europe and other overseas countries.\u00a0 Very many of, or possibly most of consumer electronics equipment has Japanese numbered parts.\u00a0 These numbers usually start with 2SA, 2SB, 2SC, or 2SD, however the transistor package has so little room that the numbers are usually abbreviated by dropping the 2S.\u00a0 For instance the 2SC1815 transistor is marked C1815.\u00a0 So if you look up the substitute for C1815, also look up the sub for 2SC1815.\u00a0 Similarly, sometimes the European makers dropped the B, so a BC547 transistor may have C547 on the package.\u00a0 The BC547 number is one of the Pro Electron number series, which originally started with A when the transistors were germanium.\u00a0 Now most transistors are silicon, which starts with a B.<\/p>\n

Many transistors have numbers similar to the JEDEC 2N numbers.\u00a0 One good example is the 2N2222A, which comes in a metal package.\u00a0 Manufacturers used the same chip in a different plastic package to make them much cheaper, and gave them a similar name such as MPS2222A or PN2222A.\u00a0 Also, the same transistor chips can be found in surface mount packages such as PZT2222A or MMBT2222A.\u00a0 There are\u00a0 also integrated circuits that have four transistors, such as the MPQ2222A, which may be very difficult to find.\u00a0 So if there is room, four individual PN2222A transistors could be used.<\/p>\n

Circuit Design<\/strong> – I should also discuss circuit design.\u00a0 In the early years of transistorized equipment, the cost of the transistor was higher and designers tended to design equipment with few transistors.\u00a0 The ultimate transistor radio “reflex” receiver used a single transistor for first amplifying the radio frequencies, then after detection, the audio was fed back through and amplified by the same transistor!\u00a0\u00a0 Consumer equipment used coils and capacitors for tuned circuits, and these had to be adjusted or “aligned” at the factory for proper operation.\u00a0 At one point the makers started using “SAW” filters which did not require alignment, and this elimination of labor saved a lot of money and time.\u00a0 So designs became more complex as automation made assembly much cheaper and less dependent on labor.\u00a0 The result is that if you are replacing the transistor in older equipment, the substitute most likely needs to be more compatible, because it is likely that the equipment will have to be re-aligned.\u00a0 More modern equipment may be much more tolerant of transistors that are not as close a substitute.<\/p>\n

Back to experimenting;…<\/p>\n","protected":false},"excerpt":{"rendered":"

I came across this forum thread where the person asks how to find and equivalent transistor.\u00a0\u00a0 First off I would like to say that if you substitute another transistor and it burns up in a few seconds, like it did in this case, then you should certainly consider that the circuit is bad in some <\/p>\n

(Read More…)<\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[23,80],"tags":[],"class_list":["post-4574","post","type-post","status-publish","format-standard","hentry","category-books-documents-literature","category-transistors"],"_links":{"self":[{"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/4574","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=4574"}],"version-history":[{"count":26,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/4574\/revisions"}],"predecessor-version":[{"id":4656,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/4574\/revisions\/4656"}],"wp:attachment":[{"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=4574"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=4574"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=4574"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}