Opencan Posted February 3, 2006 Report Share Posted February 3, 2006 I wanted to build this circuits : http://www.runoffgroove.com/grace.pdf, so I went to my local (and pretty expensive) electronics store, and bought all the parts needed, exept of the Jfet. They didn't had the exect type of what i've needed, not the 1:1 subtitutes mentioned in their book of semiconductors, and what they did had to offer me cost between 4USD to 8USD (and thoes was the cheap from the bulk). I don't want to spend so much money on thoes thing, mostly because the essay from this author and the essay led me there said i can use any N channel Jfet. So, what CHEAP models can do the work? Oh, and does 4M7 ohm is a common value for resistors? i remember i saw something like that in another electronics store, but I'm not sure about that. (anyhow, i bought 2 2M2 resistors to place each 4M7 resistors) Hope to get some encouraging answer, Ron Quote Link to comment Share on other sites More sharing options...
Samba Pa Ti Posted February 3, 2006 Report Share Posted February 3, 2006 http://www.banzaieffects.com/product.php?p...&cat=370&page=1 is that a 470 ohm resistor ? if so http://www.banzaieffects.com/product.php?p...&cat=449&page=1 Quote Link to comment Share on other sites More sharing options...
Opencan Posted February 3, 2006 Author Report Share Posted February 3, 2006 Sorry if i was unclear. I need a recomandation on a cheap subtitute to the models mentioned. I can't order from this site for the simple reason i don't pass the minimum req. and the shipping to israel will cost me way too much.... and I need a 4.7M ohm resistor (4M7 = 4.7M). but its fine, i'll use two 2.2M resistors in series. Quote Link to comment Share on other sites More sharing options...
Paul Marossy Posted February 3, 2006 Report Share Posted February 3, 2006 How about a 2N3819? It kind of sounds like you aren't going to be able to get any kind of JFET for cheap considering what part of the world you are in... Quote Link to comment Share on other sites More sharing options...
JohnH Posted February 3, 2006 Report Share Posted February 3, 2006 Ive also had trouble finding J201's For a lot of effects designs, the J201 seems to be preffered. The difference appears to be that it has a low gate-source bias voltage Vgs, compared to other types. When used in a common source arrangement, such as in most of the designs on www.runoffgroove.com for example, this results in a higher gain. The best options I have tried are 2N5457 and 2N5484, but these are not equivalent to J201, and the circuits end up with less gain. But I have still had very good results designing circuits for them. 2n3819 and MPF102 seem to have yet higher Vgs, and so offer even less gain in these applications, although they work fine where gain is not too critical, such as in buffer circuits or wher circuits are designed for them. It occurs to me, although i have not tried it, that better results may be obtained with these other JFEts, by adapting deisgns to work at a higher voltage, say 18V instead of 9V. Vgs will then be a smaller proportion of thesupply voltage, allowing a higher drain resistor to be used and improving gain. The above are just my suspicions having played with some of these recently. others please correct if you know better! J Quote Link to comment Share on other sites More sharing options...
Paul Marossy Posted February 4, 2006 Report Share Posted February 4, 2006 Oh yeah, I forgot about MPF102s. Those seem to work fairly well most of the time, too. Quote Link to comment Share on other sites More sharing options...
lovekraft Posted February 4, 2006 Report Share Posted February 4, 2006 The BF245A and the Toshiba 2SK170 are both potential substitutes, and are generally more available outside the US. Since the JFET is a simple source follower, you should be able to get pretty good results out of almost any small signal N-channel JFET, so if you find something inexpensive, it'll probably work. HTH Quote Link to comment Share on other sites More sharing options...
Opencan Posted February 4, 2006 Author Report Share Posted February 4, 2006 Paul, be surprised, but most electronics components are cheaper here than in the US, or at least equal at price. I'm pretty sure you get a way better price than the US for buying in bulk. Its just that there is less (and different) variety of components. JohnH, thank for the information, i will ask for them tomorrow when the shop will open up. And i rather not use a 18V circuits at the moment for the sole reason of comfortness. rather use 1 battery than 2. lovekraft, i'll ask for thoes as well. I did asked for any N-channel Jfet available instead but they stared at me blankly saying they know about values and not about kinds, and told me to ask an electronics expert for this kind of information... While this being my preffered place for asking question, i made you my electronics expert to cover my loss of knowledge thanks you all for the help, i'll write back tomorrow morning when i'll have an answer about thoes components Quote Link to comment Share on other sites More sharing options...
JohnH Posted February 4, 2006 Report Share Posted February 4, 2006 (edited) OPencan - when I wrote my bit about differences I have found, I was talking generally about JFETs, and as used in common source circuits which are on most of the runofgroove designs. But lovekraft is right that in that Grace design, the FET is just a source follower, which is one of the most tolerant ways of using a JFET, so as stated also in the article, any small N-channel JFET should work there. J Edited February 4, 2006 by JohnH Quote Link to comment Share on other sites More sharing options...
Opencan Posted February 4, 2006 Author Report Share Posted February 4, 2006 yeh, the problem is i know no n-channel JFET models... x_x Quote Link to comment Share on other sites More sharing options...
Paul Marossy Posted February 4, 2006 Report Share Posted February 4, 2006 (edited) the problem is i know no n-channel JFET models They're mentioned all thru this thread! J201, 2N5457, MPF102, 2N3819, BF245A & 2SK170 - these are all N-channel JFETs. Say, do they sell NTE parts? Sometimes NTE parts are another alternative. You could use this cross-reference to find what you're looking for: http://nte01.nteinc.com/nte/NTExRefSemiPro...Search?OpenForm Paul, be surprised, but most electronics components are cheaper here than in the US, or at least equal at price. I'm pretty sure you get a way better price than the US for buying in bulk. Its just that there is less (and different) variety of components Interesting. It does seem to be true that they are extremely expensive when it comes to JFETs, though! Edited February 4, 2006 by Paul Marossy Quote Link to comment Share on other sites More sharing options...
Opencan Posted February 5, 2006 Author Report Share Posted February 5, 2006 yeh, wrote them up before, but though there might be a source of info for thoes things i got no clue about NTE, but i'm sure i never came across that name before in here. and about the JFETs.. i got no clue, they gave me a 25V-50V, pretty big ones (SKsomthing i think) that cost alot, probably because they didn't get my needs or just wanted to get a few more dimes. and for example, i got once about 50 resistor and it was about 10 NIS (about 2.2 USD) and thats not all that cheap because i didn't get any discount for buying a bulk. Quote Link to comment Share on other sites More sharing options...
lovekraft Posted February 5, 2006 Report Share Posted February 5, 2006 (edited) SK/2SK (as in 2SK170 - see above) is Toshiba's prefix for all their N-channel JFETs, and 50 volts is not a big deal, it's probably just the maximum Vds. If you can get us the whole part number on the one they've got, I'll bet between us we can figure out if it'll work! Alternatively, if you can't find anything that doesn't cost the world, PM me with your physical address. I've got several (hundred - no, really!) 2N5457s on hand, and I'll bet we can smuggle you a couple out of the States! Edited February 5, 2006 by lovekraft Quote Link to comment Share on other sites More sharing options...
Opencan Posted February 7, 2006 Author Report Share Posted February 7, 2006 (edited) I'd love to do that, but on sunday morning i left my home because i should have recruited to the army and ran away. anyhow, left my electronic stuff there (didn't had time to pack them). and at the momnet i don't have a phisical address anyhow, this thing should calm in a few weeks. what i actually wanted to say, is keep me some N24548.... by the way, i love being in a commonistic comunity (e.a. Kibutz) Edited February 7, 2006 by Opencan Quote Link to comment Share on other sites More sharing options...
Opencan Posted February 13, 2006 Author Report Share Posted February 13, 2006 found a shop that got 2n5458 and got two of them. they should function the very same to the 2n5457, right? it was about 75 cents each. and another thing. i bought a soldering wire, half a kilo, for 10 bucks. is it a fair price? because it seems like a major rip to me x_x and its from one of the cheapest stores in the country.. (i've been asked for 18 bucks for the same thing in another store..) Quote Link to comment Share on other sites More sharing options...
Paul Marossy Posted February 13, 2006 Report Share Posted February 13, 2006 they should function the very same to the 2n5457, right? I think they are close enough to work as a substitute. You might want to use a trimpot or two to be able to dial it in your specific circuit. Quote Link to comment Share on other sites More sharing options...
lovekraft Posted February 13, 2006 Report Share Posted February 13, 2006 The 2N5458 has a somewhat higher Vgs(off), so it'll probably need rebiasing if it's used as a gain stage, but since this is just a source follower (no gain, no pain ), it should work without issues. And if that solder is rosin core, that doesn't sound like a bad price at all. You done good!! Quote Link to comment Share on other sites More sharing options...
black Posted October 5, 2006 Report Share Posted October 5, 2006 Guys I searched all the above components y'all have mentioned. Finally after months 'n months of searching I found a BF245C from a local shop.There was only one left in their stock.I used it for the circuit "3 legged dog" but the result was having a "2 day headache" caused by the oscillation noise.Later i found a site where you can find equevalant FETs manifactured in Russia.So guys check this out.I couldn't find the part but at least y'all give a try; KP303A KP307B KP302A KP303E KP350A Quote Link to comment Share on other sites More sharing options...
black Posted October 9, 2006 Report Share Posted October 9, 2006 WOW!!!!! friends finally, finally found J201.But the price??? 6$ each.Do you think that's a fair price? The dealer said it's expensive because it's used on Proffesional Audio Applications.I feel like he's lying. Like, c'mon there are better JFETs for cheaper prices right? Quote Link to comment Share on other sites More sharing options...
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