I had no problems getting the 2SK170 JFETs from Futurlec.\u00a0 They were on tape.\u00a0 I don’t know what manufacturer, but they are not Toshiba.<\/p>\n
Right now, I think a lot of the major semi makers are abandoning through hole parts, and going to surface mount only.\u00a0 To get a through hole part, one may have to buy a large amount (a whole reel) or get the part from a maker such as KEC (Korea Electronics), BEL (Bharat Elec) or Rohm.<\/p>\n
You can get the National Semi Discrete Data Book 1978 Edition<\/a> (PDF) from Archive.org.\u00a0 When you look up a transistor, it tells you the process that it was from.\u00a0 In other words, the chip inside the transistor is sorted from the chips made by a certain process.\u00a0 Some have higher specifications, for instance higher gain.\u00a0 Thes may be sold as 2N3904.\u00a0 The lower gain chips may be sold as 2N3903.\u00a0 But they are the same chip, and if the circuit is not critical, you may be able to substitute the 2N3904 for the 2N3903.<\/p>\n If you look in the right hand column, you may find several different transistors that use the same process. \u00a0 In the Pro Electron Series, you may find that the older transistors such as the BC107 were packaged in the TO-106 package, which is no longer made.\u00a0 But you may be able to find an equivalent transistor, such as the BC547, using the same process in the TO-92 package, which is common and still being made.<\/p>\n Regarding the 2SK170.\u00a0 It may not be recommended for new designs, but the replacement, the 2SK880, is not through hole, it’s surface mount, and that would mean redesigning the PC board.\u00a0 So the assembler must use the 2SK170 until his supply of PC boards has been used up.\u00a0 The alternative would be to try to find a substitute JFET.\u00a0 If the JFET is in the Databook, you could find out what process is used, and then find other JFETs that use that process and try to find one that would substitute for the 2SK170.<\/p>\n I also got some 2N7000 MOSFETs.<\/strong>\u00a0 They also came on tape, but the tape has the side toward the MOSFETs coated with aluminum foil.\u00a0 This is to prevent damage from static electricity.\u00a0 The MOSFETs are held onto the the tape with masking tape.\u00a0 Normally the leads are cut off above the tape as the part is put into the PC board.\u00a0 The masking tape is never disturbed.\u00a0 But in my case, I don’t have a machine so I usually pull the part off the tape, and sometimes the masking tape pulls of with the part, sometimes it stays on the tape and the part leads pull free.\u00a0 The problem here with the MOSFETs is they are more sensitive than JFETs to static.\u00a0 That’s why there’s the aluminum foil.\u00a0 And the masking tape is triboelectric.\u00a0 This means when the tape is pulled off, it generates static electricity.\u00a0 So by pulling off the MOSFETs I could be causing them to burn out.<\/p>\n What to do?\u00a0 I could try to duplicate the machine and just cut the leads off above the tape.\u00a0 But then the leads are shortened and obviously not the same as when they were made.\u00a0 My thoughts are that if I squeeze the 3 leads between my fingers and pull the MOSFET off the tape, the static from the masking tape will go through my fingers and not damage the MOSFET.\u00a0 Or should I try to cut the masking tape off before I pull the MOSFET off the foil?\u00a0 I’ll have to experiment a bit to find out how each works.<\/p>\n <\/p>\n","protected":false},"excerpt":{"rendered":" I had no problems getting the 2SK170 JFETs from Futurlec.\u00a0 They were on tape.\u00a0 I don’t know what manufacturer, but they are not Toshiba. Right now, I think a lot of the major semi makers are abandoning through hole parts, and going to surface mount only.\u00a0 To get a through hole part, one may have <\/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":[74],"tags":[],"class_list":["post-6753","post","type-post","status-publish","format-standard","hentry","category-electronic-components"],"_links":{"self":[{"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/6753","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=6753"}],"version-history":[{"count":8,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/6753\/revisions"}],"predecessor-version":[{"id":6755,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/6753\/revisions\/6755"}],"wp:attachment":[{"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=6753"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=6753"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=6753"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}