Re: all-BJT LED driver (was re: Transistor as a current limiter)

- J
- John Larkin
  
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posted
10 years ago

Thu, Jul 18, 2013 5:48 PM

>
>> >>Saturated BJT in the diff-amp? > >(The base drive will have to be significant, relative to the >common diff-amp emitter currents. That means a stiff divider. >Gain will also be poor, I believe.) > >Jon

Actually, this works better than I thought it would, given the constraint of no opamps but ignoring the constraint of no mosfets.

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It servoes Vsrc down to 10s of millivolts. Seems to be closed-loop AC stable, too.

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Q2 base current is nanoamps.

--

John Larkin         Highland Technology, Inc 

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http://www.highlandtechnology.com 

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