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Tweakers' Asylum Tweaks for systems, rooms and Do It Yourself (DIY) help. FAQ. |
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Tweakers' Asylum Tweaks for systems, rooms and Do It Yourself (DIY) help. FAQ. |
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In Reply to: Current >T1 at the same time as current >T2, can not... posted by groman on January 8, 2002 at 14:53:02:
Hi Groman,
I am not still sure I understand what you mean.
Do you mean by the title of your post that the cutrrent through T1 can not be equal to the current through T1??? By "current" I mean the curent from collector to emittor(bipolar transistor) or from drain to source(FET)
I just found a nice schematic on DIYaudio.com, just click on the link below and this makes it more easy to talk about the circuit.
I do use the resistors R1 and R2 in the source leads AND a active constant current source. If you want the said currents to be equal all things have to be equal. That includes the two FET's and the two resistors.
This goal can only be achieved, for the DIYer with a monolitic Dual JFET such as the 2SK389 or the industry standard 2N5912. If the two halves of the input differential pair are equal the current from the current source will split up equally between the two halves.
Anyway the differential pair only works by virtue of the exact equality of the two halves. Only James Bongiorno will argue that the matching of the inut transistors is not necessary, but that's a other story.
I also have practical experience in matching transistors for input differential pairs, matched does sound a lot better! And Duals even more!
ELSO
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Follow Ups
- Re: Current >T1 at the same time as current >T2, can not... - Elso Kwak 01/9/0202:09:12 01/9/02 (0)
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