tag:blogger.com,1999:blog-6847048658257278783.post2251401390306159117..comments2024-03-29T01:36:12.851+00:00Comments on Guitar FX Layouts: Greatly Improved JFET MatcherIvIarkhttp://www.blogger.com/profile/08416945174853142251noreply@blogger.comBlogger41125tag:blogger.com,1999:blog-6847048658257278783.post-43768258547109665282022-08-08T23:42:25.404+01:002022-08-08T23:42:25.404+01:00Is the opamp acting as a buffer there? Won't i...Is the opamp acting as a buffer there? Won't it limit the mÃnimum Vp reading to 1.5V, since that's the lowest the opamp can go at the output?Dazzhttps://www.blogger.com/profile/07619622297229101066noreply@blogger.comtag:blogger.com,1999:blog-6847048658257278783.post-11508283733580386852022-04-17T03:23:47.096+01:002022-04-17T03:23:47.096+01:00Those values match what you'd expect from a 2S...Those values match what you'd expect from a 2SK170, specifically the BL variant: Vp -0.2-1.5V, Idss 6-12mA<br /><br />For future reference, you can find the spec'd values in the datasheet: https://www.mouser.com/datasheet/2/408/6909-57550.pdfCrackinTheShathttps://www.blogger.com/profile/00188367058561946285noreply@blogger.comtag:blogger.com,1999:blog-6847048658257278783.post-25206243865915800042020-11-10T04:29:24.455+00:002020-11-10T04:29:24.455+00:00Aloha,
I've just put together the Greatly Imp...Aloha,<br /><br />I've just put together the Greatly Improved JFET Matcher II on a breadbaord and have tested two 2SK170 (for discrete Op-amp build). The figures I get are: 0.67V/9.38mA & 0.62V/7.05mA. <br /><br />I'm wondering if someone can confirm that these figures jive with what I should expect from an authentic component. I Bought them NOS from a local electronic store whose sales clerk told me he hadn't sold any since 2011...Anonymoushttps://www.blogger.com/profile/06373594833637197057noreply@blogger.comtag:blogger.com,1999:blog-6847048658257278783.post-53626369514354140072020-05-07T12:23:16.722+01:002020-05-07T12:23:16.722+01:00Built this on a breadboard. Got 3 matched pairs fr...Built this on a breadboard. Got 3 matched pairs from my 10 pack of J201s :)DChttps://www.blogger.com/profile/15345191501625113444noreply@blogger.comtag:blogger.com,1999:blog-6847048658257278783.post-54586316694781756382020-05-07T11:37:55.027+01:002020-05-07T11:37:55.027+01:00Sorry, the answer below is correct. I am talking a...Sorry, the answer below is correct. I am talking about the voltage readings that you get after disconnecting power. I built this on a breadboard and don't have a switch, just jumpers that I move around.DChttps://www.blogger.com/profile/15345191501625113444noreply@blogger.comtag:blogger.com,1999:blog-6847048658257278783.post-4617441967480736192020-05-07T11:35:09.780+01:002020-05-07T11:35:09.780+01:00I know this is an ancient question, but people sti...I know this is an ancient question, but people still refer here. What you are seeing is residual capacitance from the 47u DC smoothing capacitor. After disconnecting the power, the capacitor starts slowly discharging. If you watch the voltage reading it will slowly start to drop.DChttps://www.blogger.com/profile/15345191501625113444noreply@blogger.comtag:blogger.com,1999:blog-6847048658257278783.post-54480311608917320062019-11-15T20:36:11.539+00:002019-11-15T20:36:11.539+00:00How about using 2N3819 as I have 10 approx lying a...How about using 2N3819 as I have 10 approx lying around in spares boxAnonymoushttps://www.blogger.com/profile/18327069758903603161noreply@blogger.comtag:blogger.com,1999:blog-6847048658257278783.post-37635215786447694272019-08-11T22:06:30.723+01:002019-08-11T22:06:30.723+01:00hi,
it is very good!
such a beautiful tool!
we o...hi, <br /><br />it is very good!<br />such a beautiful tool!<br />we only have to use the Voltmeter to get two readings... including a current value :)<br /><br />NOTE:<br />the switch mentioned in the layout DPDT -- aka 2P2T ...<br />per def does NOT have a mid setting...<br />only 2, A and B :)<br /><br />so I suggest either buying a 2P3T switch :)<br />or placing 2 switches on the board...<br />which I did...<br /><br />one to turn it ON and OFF..<br />and one to choose the measurement method...<br /><br />I also suggest adding at least one LED... as an indicator of the ON state :) but there could be another one, too, indicating the measurement, although this is totally NOT necessary...<br />only decoration :)<br /><br />but the ON LED is important, I think...<br /><br />I suggest making this not in a box whatsoever...<br />but as flat thing, I used a beer pad -- see my post at guitar-fx-layouts: <br />http://guitar-fx-layouts.42897.x6.nabble.com/which-jfet-matcher-do-you-use-think-is-most-reliable-td30460.html#a47122j-peehttps://www.blogger.com/profile/06075769174607916244noreply@blogger.comtag:blogger.com,1999:blog-6847048658257278783.post-59568355793444214632019-06-13T04:04:20.432+01:002019-06-13T04:04:20.432+01:00i've just built this little jewel, to run some...i've just built this little jewel, to run some tests...it gives me strange results: 9 2n5457 tried: 2 of them give 3.5v; 2 of them 0.9v (i think they are faulted); 5 of them are 0.4v...does anyone knows which is the "right" value of this circuit for 2n5457?<br />anyway, for anyone who builds this, i suggest this item: LCR-T4 328 mega...you can find for a few bucks on ebay, and it's really usefull and quite precise; it identifies every component you put on, without minding the pinoutcrustonehttps://www.blogger.com/profile/01989869760199672592noreply@blogger.comtag:blogger.com,1999:blog-6847048658257278783.post-14996627714132581212017-06-04T06:36:53.203+01:002017-06-04T06:36:53.203+01:00Shitty imitation JFETs from China is my guess. I t...Shitty imitation JFETs from China is my guess. I tried it with some good ones from guitarpcb and they worked fine. Anonymoushttps://www.blogger.com/profile/05814602349472879756noreply@blogger.comtag:blogger.com,1999:blog-6847048658257278783.post-64456515092152419962017-06-03T04:16:43.718+01:002017-06-03T04:16:43.718+01:00You either put the jfet in the wrong way or have a...You either put the jfet in the wrong way or have an error in your build. These jfet are very sensitive, I have burned up a few just using a meter probe and shorted them to ground. this tester is extremely accurate and useful for lots of jfet builds<br /><br />.what are you making Jay? Good luck triple check your build before trying any more jfets. I seem to make more mistakes on the easy builds than the mega ones.If you want to post some pics of your matcher i would be happy to help check it for you.Anonymoushttps://www.blogger.com/profile/09475485559085932632noreply@blogger.comtag:blogger.com,1999:blog-6847048658257278783.post-54478083665100404322017-06-03T04:16:04.808+01:002017-06-03T04:16:04.808+01:00You either put the jfet in the wrong way or have a...You either put the jfet in the wrong way or have an error in your build. These jfet are very sensitive, I have burned up a few just using a meter probe and shorted them to ground. this tester is extremely accurate and useful for lots of jfet builds<br /><br />.what are you making Jay? Good luck triple check your build before trying any more jfets. I seem to make more mistakes on the easy builds than the mega ones.If you want to post some pics of your matcher i would be happy to help check it for you.Anonymoushttps://www.blogger.com/profile/09475485559085932632noreply@blogger.comtag:blogger.com,1999:blog-6847048658257278783.post-7554910913150944662017-06-02T21:18:58.003+01:002017-06-02T21:18:58.003+01:00I tried testing a J201 with the smaller version an...I tried testing a J201 with the smaller version and it got hot and smoked. Why?Anonymoushttps://www.blogger.com/profile/05814602349472879756noreply@blogger.comtag:blogger.com,1999:blog-6847048658257278783.post-52354994970179934462017-03-29T15:28:27.651+01:002017-03-29T15:28:27.651+01:00firstly, apologize for my comment about the mpf102...firstly, apologize for my comment about the mpf102 get smoke on the board.. I know whats the matter now, the only things need to pay attention is [china market], the answer is here: http://i1244.photobucket.com/albums/gg569/pakkee66/DIY%20PEDAL/fake%20mpf102_zpsru1opnxh.jpg <br />so that's it..and sorry again.pakkee66https://www.blogger.com/profile/12727597403973037143noreply@blogger.comtag:blogger.com,1999:blog-6847048658257278783.post-81867158408434239672017-03-21T15:25:25.049+00:002017-03-21T15:25:25.049+00:00This comment has been removed by the author.pakkee66https://www.blogger.com/profile/12727597403973037143noreply@blogger.comtag:blogger.com,1999:blog-6847048658257278783.post-89458021402031311522017-03-15T14:40:50.903+00:002017-03-15T14:40:50.903+00:00built the IC version and was able to match 4 jfets...built the IC version and was able to match 4 jfets for a phaser. thank!!Anonymoushttps://www.blogger.com/profile/14321041071510938445noreply@blogger.comtag:blogger.com,1999:blog-6847048658257278783.post-50793377531732461992016-12-21T12:36:55.507+00:002016-12-21T12:36:55.507+00:00I built the IC version and matched a quad of 2N548...I built the IC version and matched a quad of 2N5485's within 5mv for a phase 90. Works brilliantly, thank you!Chancehttps://www.blogger.com/profile/03508039283950531588noreply@blogger.comtag:blogger.com,1999:blog-6847048658257278783.post-6216018465547597942015-03-20T01:25:35.076+00:002015-03-20T01:25:35.076+00:00Hi All, I have built the non ic version, and have ...Hi All, I have built the non ic version, and have the same issue as you guys. Is there a fix for this or another good way to match the 2N5952's, I am not up to speed with Idss, Vp,Vgs and so on, Can some one give me an actual example..........at my age, I need all the help I can get...<br />Regards PeterAnonymoushttps://www.blogger.com/profile/13630288170978122679noreply@blogger.comtag:blogger.com,1999:blog-6847048658257278783.post-14214888976472142982015-03-06T03:35:41.976+00:002015-03-06T03:35:41.976+00:00Okay here's a stupid question... when are meas...Okay here's a stupid question... when are measurements close enough to "match" transistors? I understand from the ROG post that I don't need exact to-the-decimal matches, but what's the acceptable margin?jaredmcohenhttps://www.blogger.com/profile/14303382501202040317noreply@blogger.comtag:blogger.com,1999:blog-6847048658257278783.post-92219655606504641732014-10-07T07:30:23.747+01:002014-10-07T07:30:23.747+01:00I just built the no IC version myself and I don...I just built the no IC version myself and I don't seem to be able to make it do much of anything.I went with an off switch and a DPDT switch to go between Idss and Vp. I figured the idea was to read DC mv on your meter, but my readings are 00 to .1 at best. motterpaulhttps://www.blogger.com/profile/15536330842070250774noreply@blogger.comtag:blogger.com,1999:blog-6847048658257278783.post-46208815215109306992014-06-20T02:04:37.744+01:002014-06-20T02:04:37.744+01:00Hey, could someone revisit the no-IC layout, to fi...Hey, could someone revisit the no-IC layout, to fix the issue of not having an off-position? Vp comes through on the middle position.agitprophttps://www.blogger.com/profile/07084651352784919007noreply@blogger.comtag:blogger.com,1999:blog-6847048658257278783.post-69241892474050018712013-09-17T18:05:34.523+01:002013-09-17T18:05:34.523+01:00Could we not design a circuit with a 15 turn pot s...Could we not design a circuit with a 15 turn pot so that we could dial in a precise ohm per what ever v we are shooting for and then sub fixed resistors in the circuit were building so that instead of having to match jfets we can simply bias each jfet that's going in the circuit and use the "r" the values to keep them biased at the same v? Anonymoushttps://www.blogger.com/profile/08939334402638913882noreply@blogger.comtag:blogger.com,1999:blog-6847048658257278783.post-85499013996538497082013-08-30T15:51:42.696+01:002013-08-30T15:51:42.696+01:00Can I find an updated layout anywhere for this? Can I find an updated layout anywhere for this? Gc66https://www.blogger.com/profile/12510711522660935373noreply@blogger.comtag:blogger.com,1999:blog-6847048658257278783.post-49064344831418308242013-08-14T09:00:23.901+01:002013-08-14T09:00:23.901+01:00I built the non-IC version, but like the others I ...I built the non-IC version, but like the others I get Vp reading in the middle position. If you check the linked schematic from ROG, it is clear why: in the center position the 9V is not off, but the DMM measures the voltage on both resistors in series. Now 100Ohm is like nothing compared to 1MOhm, so basically in the middle position you measure the same voltage as on the 1MOhm resistor only. As a solution you can use a DPDT on-off-on 3-position switch. In this case you would connect the +9V connection of the circuit to the middle lug (lug nr 5) and connect the both outer lugs (4 and 6) both to the +9V supply. If you do this then in the middle position the 9V is not applied to the circuit and you have it switched of.drdFXhttps://www.blogger.com/profile/05100895565160403133noreply@blogger.comtag:blogger.com,1999:blog-6847048658257278783.post-46379938092692540312013-07-17T11:18:52.863+01:002013-07-17T11:18:52.863+01:00I've build the no IC version. I get Vp reading...I've build the no IC version. I get Vp readings in all positions of the switch, but no Idss. I was able to match 4x J201. I just remove the battery when I change a JFET. For my DMM measuring I use two sockets.H.A.M.https://www.blogger.com/profile/02399769166829260024noreply@blogger.com