macgyver Posted November 9, 2011 Report Posted November 9, 2011 Hallelujah!! Here is our work shed. The amp is making music. I did say a serious prayer before I turned it on Hi, i'm a new user. Congratulation for this perfect work!!!!! I'm starting to make my first project, and i want to know were i can buy a case amp like that you have used in this project. Maybe a little bit higher. Thanks and best regards. Mac.
spritzer Posted November 9, 2011 Author Report Posted November 9, 2011 The case was custom made from custom extrusions. This can't be bought anywhere.
Pars Posted November 11, 2011 Report Posted November 11, 2011 (edited) Good thing to see some vendor info in this thread. I am looking for some IRF230s for my brother's amp, and here is what UTsource sent as far as a device picture: The markings on this don't look like any IRF I've seen... do these ring a bell with anyone else? I guess I'll have to go with Newark. Just as a follow up. UTsource kept sending me an email reminding me to order these, so I replied back. Here is their reply: ok, thanks! davis ======================================================================= http://www.utsource.net YOUR ONE STOP SOURCE FOR ELECTRONIC COMPONENTS UTSOURCE.NET power by UTSOURCE International(S) Pte.Ltd. Singapore Service Line : TEL : 0065-315-631-17 Email: [email protected] USA Service Line : TEL : 001-818-698-1878 Email: [email protected] &nb sp; China Service Line : TEL : 0086-755-23959113 Fax : 0086-755-23959192 Email: [email protected] -------------------------------------------------- 发件人：Chris Young 发送时间：2011-11-10 21:10:31 收件人：[email protected] 抄送： 主题：Re: Please place order to us for IRF230 Devices do not look genuine. No thanks. Edited November 11, 2011 by Pars
Pars Posted November 21, 2011 Report Posted November 21, 2011 <snip> Get yourself one of these http://www.ebay.com/...=item1c1d98666e and test all the high voltage transistors before you put them in. Are these things good enough to measure (and match) small signal devices for hFe? Might need one for my Christmas list...
luvdunhill Posted November 21, 2011 Report Posted November 21, 2011 Are these things good enough to measure (and match) small signal devices for hFe? Might need one for my Christmas list... It depends. First, how linear is the device being tested with respect to hfe versus Ib? If it's linear, then perhaps it would work. If not, or you like to match at the actual circuit conditions, then you'll be out of luck.
kevin gilmore Posted November 21, 2011 Report Posted November 21, 2011 much more suitable for quick go/no go, and for obvious fakes. for critical matching you have to build something custom.
Pars Posted November 21, 2011 Report Posted November 21, 2011 (edited) I have a test fixture that I use with 2 DMMs and a bench supply now, but it is time consuming (I'm sure you both know all about that ). I just saw that this thing had at least 3 Ib ranges (10uA, 1mA and 10mA) and thought it might do the trick for all but critical matches. Probably something worth having anyhow, particularly given the price. Intended devices would be stuff like 2SA970/SC2240, 2SA1016 and it's complement, etc. Edited November 21, 2011 by Pars
luvdunhill Posted November 21, 2011 Report Posted November 21, 2011 1mA and 10mA Ib ranges are likely useless to you. Think about what devices you'll be matching and their hfe and then the target collector current. Then report findings back
Pars Posted November 22, 2011 Report Posted November 22, 2011 The 10uA should be useful. Was setting up my test fixture (if you can call it that) last night, and going thru some previous measurements. I'm using 24uA Ib and Ic is ~12-15mA. 10mA is probably my Ic target in general. On a BL device, the 10uA would get me to between 3.5 and 7mA Ic which is probably close enough. I have no idea what the POS Centras or whatever that Harbor Freight DMM uses for hFe... probably much less than 10uA though.
luvdunhill Posted November 22, 2011 Report Posted November 22, 2011 (edited) My only issue would be whether or not 10mA collector current really needs the device to be heatsinked, especially with positive tempco device such as BJTs. My experience is yes, in order to get good matches. If you are talking about to-92 device you might be okay.. Edited November 22, 2011 by luvdunhill
ujamerstand Posted November 25, 2011 Report Posted November 25, 2011 So I was in a local electronic shop the other, shopping for some test rig material. There I found that they have a small collection of japanese transistors, and I found these stuffed into a tiny compartment: Looks like some real units are mixed with other very questionable quality units. They also have 2SK246GR, some 2SK216, K170, and apparently they are waiting for LSJ74 to appear. Quite surprised at what they offer locally.
kevin gilmore Posted November 25, 2011 Report Posted November 25, 2011 (edited) walk in with the el-cheapo transistor tester, test them all, and buy the real ones. Say 50 cents each... Kind of surprised that someone would stock those, and that they were bent into shape like that. Edited November 25, 2011 by kevin gilmore
justin Posted November 25, 2011 Report Posted November 25, 2011 MCM used to sell the 2sc3675 with bent legs like that. it was annoying.
ujamerstand Posted November 26, 2011 Report Posted November 26, 2011 Definitely won't be buying any. haha They were asking for $3.1 a unit, and I already have plenty. Not really worth the trouble. Did get myself a large piece of heat sink though.
spritzer Posted November 26, 2011 Author Report Posted November 26, 2011 I bought some 3675's locally that looked very strange to say the least but they do test like the real thing.
spritzer Posted November 27, 2011 Author Report Posted November 27, 2011 Yup, they had them. I never pay list though... They also had a bag of J109's...
pedefede Posted November 29, 2011 Report Posted November 29, 2011 (edited) Black sheep has been finished (almost): http://dl.dropbox.co...phone%20326.jpg (quick iphone pic in the dark) Noise issue solved - Replaced shinkohs 390K, 820K, 100R in one of the batteries for xicons. There is NO noise now, even at full volumen. Feels a bit wierd actually, to put the beast to full volumen, and to be unsure wether it has been turned on ... (I allmost blew my ears, when i accidently left the volumen at 100%, and put on a 1 KHz sinus signal ... ) You can measure the 50Hz noise from the unregulated heaters on the batteries ... but during to the balanced nature of the beast - it is canceled at output It plays fantastic ... I still have some to-do stuff (balanced volumen attenuater with fixed resistors, optimizing balance by switching tubes, trying with current-stock.tubes, eventually replacing more resistors for Xicons) (During measuring - i discoverd a small volumen-dependent oscillation (200KHz, 30mV pp at 100% volumen) . Too small to cure for now. - but that can wait ... now i really just wanna listen to the sweet, sweet music - and improve my signal sources, to match this thing ....! peter Edited November 29, 2011 by pedefede
Pars Posted November 29, 2011 Report Posted November 29, 2011 (edited) They also had a bag of J109's... Had being the key word, I suppose? Edited November 29, 2011 by Pars
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