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#1 |
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diyAudio Member
Join Date: Jul 2005
Location: D-55629 Schwarzerden
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Single transistors (i. e. without internal darlington topology) with very high hfe up to 3000 are not often to find.
Here some examples: NEC 2SC3616 http://www.classiccmp.org/rtellason/...ta/2sc3616.pdf NEC 2SC3622 - 2SC3624 (1000-3200) http://www.classiccmp.org/rtellason/...ta/2sc3624.pdf http://www.datasheetcatalog.org/data...s4d8q8si3y.pdf http://www.datasheetcatalog.org/data...8kuyykgefy.pdf Sanken 2SC3852 http://www.sanken-ele.co.jp/en/prod/...f/2sc3852e.pdf Sanyo 2SC3807 http://www.datasheetcatalog.org/data..._e/2SC3807.pdf Sanyo 2SC3689 (800-3200) / 2SA1434 (500-1200) http://www.datasheetcatalog.org/data..._e/2SC3689.pdf http://www.datasheetcatalog.org/data..._e/2SA1434.pdf Sanyo 2SC3068/2SA1435 http://www.datasheetcatalog.org/data..._e/2SC3068.pdf http://www.datasheetcatalog.org/data..._e/2SA1435.pdf Sanyo 2SC3576 http://www.datasheetcatalog.org/data..._e/2SC3576.pdf Which benefits are there in opposite to a darlington topology? Are there particularly suited for certainly amplifier topologies? Which certain applications are there, where normal darlingtons are not a good choice? Thank you for comments. |
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#2 |
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diyAudio Member
Join Date: Dec 2005
Location: Kuala Lumpur
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Interesting. These are like the "super-beta" devices found in some old opamps.
They were obviously specced for switching as the current does not go below 10mA in the gain graphs. You get high beta by having a very thin base, which gives low Vceo The ft is good compared with a darlington and saturation voltage is much lower |
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#3 |
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Account disabled at member's request
Join Date: May 2006
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Ill add some to that list in a day or two.
High voltage ones are available, I use them in inputstages and in beta enhanced vas sometimes. Great for input LTP s as it improves DC offset problems. MPSA18 is probably the most used one, excellent for LTP. Higher current examples are excellent for use as VBE multipliers. |
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#4 |
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diyAudio Member
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I am interested in the possibility of using a super-beta driven by a tube because small signal tubes don't like to drive into the relatively low impedance of a regular BJT. So I'm wondering how do they compare with FETs (also tube friendly to drive) in terms of linearity, capacitance and reliability ?
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"The test of the machine is the satisfaction it gives you. There isn't any other test. If the machine produces tranquility it's right. If it disturbs you it's wrong until either the machine or your mind is changed." Robert M Pirsig. |
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#5 |
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diyAudio Member
Join Date: Dec 2005
Location: Kuala Lumpur
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I wouldn't call the MPSA18 a super-beta, with Hfe > 500, not that much better than the old BC549C.
With Ft of about 100MHz, gain is going to start falling at around 100KHz |
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#6 | |
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diyAudio Member
Join Date: Jul 2005
Location: D-55629 Schwarzerden
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Quote:
MPSA18 MOT: hfe 500-1500 (DC, Ic = 10mA) http://www.datasheetcatalog.org/data...ola/MPSA18.pdf BC546C-BC550C NXP hfe 420-800 (DC, Ic = 2mA) http://www.nxp.com/documents/data_sheet/BC549_550.pdf http://www.radiotechnika.hu/images/BC546_50.pdf go also to MPSA 18 vs. BC546B's But to a closer view to the exactly curvatures you are right with your view in your previous post because it is not possible, to compare the mentioned current gain values without the conditions of measurement. Sometimes the collector currents are different, sometimes the Uce voltage. Additional this is still a frequency dependend value (compare DC-HFe and AC-HFe). Unfortunately all the other high Hfe types from Motorola's MPS-series are darlingtons: mps6724-6725 mpsa12-14-13-25-26-27-28-29-62-63-64-65-66-75-76-77 mpsd04-54 (only1000) mpsu45-95 mpsw13-14-45-45a-63-64 BTW - The MPSA18 is sourced from Process 07 (according an old Fairchild Databook) other types from this process are follow: http://www.fairchildsemi.com/ds/2N/2N5088.pdf http://sm0vpo.com/_pdf/BC/BC847S.pdf Last edited by tiefbassuebertr; 8th December 2011 at 10:16 AM. |
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#8 |
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Account disabled at member's request
Join Date: May 2006
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A closer look at the datasheets will give you a better answer, compare apples with apples. The bc549C has a hfe of 500 at 2ma while the mpsa18 has more than double that (1100) at the same IC. The hfe of 500 you state for the mpsa18 is at 10 ua, at this current level the bc549c only manages 150. Also the ft of mpsa18 is around 400Mhz at 10 ma and still rising while the bc549c manages max ft of 300Mhz at 10Mhz whereafter it starts declining. The mpsa18 is far superior to the bc549c series in all respects, including lower noise and lower Cob too.
Last edited by homemodder; 9th December 2011 at 12:19 PM. |
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#9 |
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diyAudio Member
Join Date: Jul 2005
Location: D-55629 Schwarzerden
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More high gain examples from Japan:
2SD2159 (Rohm hfe 390-2700) 2SB1461/2SB1425 (Rohm hfe 270-1200) 2SD2172 (Rohm hfe 560-2700) http://www.datasheetcatalog.org/data...90/90250_1.pdf No datasheet online 2SD2356-2SD2226K (Rohm hfe 560-2700) 2SD2227S (Rohm hfe 1200-2700) Datasheet from March 1997: 2SD2171S pdf, 2SD2171S description, 2SD2171S datasheets, 2SD2171S view ::: ALLDATASHEET ::: 2SC3615/2SC3616/2SC3622/2SC3622A (NEC hfe 800-3200) 2SC3615 pdf, 2SC3615 description, 2SC3615 datasheets, 2SC3615 view ::: ALLDATASHEET ::: 2SC3616 pdf, 2SC3616 description, 2SC3616 datasheets, 2SC3616 view ::: ALLDATASHEET ::: http://www.datasheetcatalog.org/data...8kuyykgefy.pdf 2SA1409, 2SA1410 (NEC no data) |
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#10 |
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diyAudio Member
Join Date: Nov 2009
Location: algeria/france
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Any improvement in some caracteristics will inevitably reduce the abilities
of the device in some other areas. The Hitachi/Renesas 2SA872/2SC1775 complementary pair has respectable gain of up to 1200 , certainly less than the super beta devices debated above , but more certainly they have high VCE and FT , very low noise and are somewhat a very wise compromise in matter of global caracteristics. |
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