Yeah you could use that. Do note that it needs 10V to turn it off though.
No. The open collector arrangement is to drive the fet gate from a bipolar transistor.
I'll crosspost it now.
Oh and please try to avoid top-posting, thanks.
Graham
correctly.
application?
bidirectional ).
into the
asomehow
this
OK.....
I've posted the schem a few times over the last 24 hrs or so, but it isn't appearing here, so I don't know if it's appearing where you are. I wonder if it is getting stripped or something.
Is anyone seeing my other posts with the schem?
Thanks
correctly.
application?
bidirectional ).
into the
asomehow
this
In message , dated Sat, 16 Sep
2006, tempus fugit writesPost it ONLY to ABSE. It will be stripped if you post to SEB as well.
No.
-- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk There are benefits from being irrational - just ask the square root of 2. John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK
This is not really accurate, to wit:
The 2nd harmonic distortion of a naked bipoler input is Vi(mv)%. That is, with 1mv AC peak vbe the distortion is aproximatly 1%. This is, of course rather large for such a small signal. (see
However, with an emmiter follower, the distortion is reduced by two facters. One the attenuation of re/Re, and two, the effect of local feedback. That is, the output is in series with the input.
Suppose, we have 1ma IE, and a 5k emitter resister (5V drop, 10V supply). At 1ma re=25 ohms. With a 1V signal, the signal at Vbe will be
1x25/5k = 5mv, generating a nominal 5%. However, the local loop feedback gain can be shown to also be re/Re, so this figure is reduced to 5%.25/5k = 0.025%.For larger signals, the distortion will go up with the square, but it is debatable just what level of distortion is significant.
As far as noise goes, the follower just adds its basic transistor thermal and shot noise, the emitter resister has negligible effect. This is in contrast to retaining the emitter resister to reduce distortion, but taking the output from the collector, whence the emitter resister will generate an additional 5k of input thermal noise.
Kevin Aylward B.Sc. snipped-for-privacy@anasoft.co.uk
"There are none more ignorant and useless,than they that seek answers on their knees, with their eyes closed"
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