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Re: Fast buffer idea

Newsgroups sci.electronics.design
Subject Re: Fast buffer idea
From Steve Wilson <no@spam.com>
References (5 earlier) <dpcjhclpajjafaf2nq0q7l7nt17jl40spo@4ax.com> <EEiSA.74451$bl5.68044@fx25.iad> <IMiSA.118013$ef.91898@fx34.iad> <XnsA7767E5052407idtokenpost@69.16.179.22> <ofcldu$n1m$1@gioia.aioe.org>
Message-ID <XnsA776875EB8A7idtokenpost@69.16.179.23> (permalink)
Organization http://www.NewsDemon.com
Date 2017-05-15 17:18 +0000

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Jan Panteltje <pNa0nStpealmtje@yahoo.com> wrote:

> On a sunny day (Mon, 15 May 2017 16:24:56 GMT) it happened Steve
> Wilson <no@spam.com> wrote in
> <XnsA7767E5052407idtokenpost@69.16.179.22>: 
> 
>>bitrex <bitrex@de.lete.earthlink.net> wrote:
>>
>>> On 05/15/2017 10:09 AM, bitrex wrote:
>>>> On 05/15/2017 10:01 AM, John Larkin wrote:
>>>>
>>>>> BW is 230 MHz as a unity-gain buffer. Each half of the dual will
>>>>> source and sink 88 mA. And there are lots of faster THS-series
>>>>> parts. 
>>>>>
>>>>>>
>>>>>> But indeed you can do that with a few NPNs of the old days,
>>>>>>
>>>>>
>>>>> Post it.
>>>>
>>>> With discretes you can have:
>>>>
>>>> 1) wide bandwidth
>>>>
>>>> 2) low parts count
>>>>
>>>> 3) low quiescent current draw
>>>>
>>>> Pick two.
>>> 
>>> The two transistor circuit Jan posted does have a pretty wide
>>> bandwidth and a low parts count. It has a pretty nice small signal
>>> output impedance, but its large-signal output impedance is bad. It
>>> also draws a  relatively large amount of quiescent current. 
>>
>>I somehow missed the two transistor circuit that Jan posted. Can you 
>>please repost the link?
>>
>>Thanks
> 
> From:
>  http://panteltje.com/panteltje/quadcopter/hud.html
>  the circuit diagram:
>   http://panteltje.com/panteltje/quadcopter/hud-0.1_circuit_diagram_IMG
>   _5984.JPG bottom left:
> that has a gain of 2, so can drive a 75 Ohm cable with reasonable Zi.
> The DC path requires an other 75 Ohm at the end of the cable.

OK, thanks.

That is a Sziklai Pair with a voltage divider in the feedback path:

  https://en.wikipedia.org/wiki/Sziklai_pair 

It would normally have the same thermal drift as a simple base-emitter 
junction, but the divide by two may increase it.

The output impedance may be increased due to the low loop gain. The 
bandwidth is determined by the transistors you use.

But it is difficult to tell what the transistors are due to the poor 
clarity of the handwritten numbers. I can't read them even when I expand 
the drawing.

I really wish you could convert some of your critical circuits to LTspice 
so we can see the operation a bit better. That would have a far greater 
impact for the value of your work.

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Thread

Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-14 13:50 -0400
  Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-14 11:27 -0700
    Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-14 19:19 +0000
      Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-14 15:24 -0400
      Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-14 12:54 -0700
        Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-14 16:02 -0400
          Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-14 13:10 -0700
            Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-14 16:16 -0400
              Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-14 16:18 -0400
              Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-14 14:14 -0700
              Re: Fast buffer idea "Kevin Aylward" <kevinRemovAT@kevinaylward.co.uk> - 2017-05-15 19:51 +0100
                Re: Fast buffer idea John Larkin <jjlarkin@highland_snip_technology.com> - 2017-05-15 13:17 -0700
                Re: Fast buffer idea Clifford Heath <clifford.heath@gmail.com> - 2017-05-17 09:14 +1000
                Re: Fast buffer idea John Larkin <jjlarkin@highland_snip_technology.com> - 2017-05-16 16:26 -0700
                Re: Fast buffer idea "Tim Williams" <tiwill@seventransistorlabs.com> - 2017-05-17 02:04 -0500
        Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-14 20:26 +0000
          Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-14 16:31 -0400
          Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-14 16:43 -0400
          Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-14 14:17 -0700
            Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-14 21:53 +0000
              Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-14 16:14 -0700
                Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-14 19:59 -0400
                Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-14 20:06 -0700
                Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-15 00:16 +0000
                Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-14 20:10 -0700
                Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-15 03:28 +0000
                Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-14 20:48 -0700
                Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-15 04:17 +0000
        Re: Fast buffer idea Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-15 07:56 +0000
          Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-15 06:58 -0400
            Re: Fast buffer idea Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-15 12:59 +0000
          Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-15 07:01 -0700
            Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-15 10:09 -0400
              Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-15 10:18 -0400
                Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-15 08:56 -0700
                Re: Fast buffer idea Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-15 16:02 +0000
                Re: Fast buffer idea John Larkin <jjlarkin@highland_snip_technology.com> - 2017-05-15 10:33 -0700
                Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-15 18:15 +0000
                Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-15 14:25 -0400
                Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-15 14:26 -0400
                Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-15 16:24 +0000
                Re: Fast buffer idea Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-15 16:36 +0000
                Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-15 17:18 +0000
                Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-15 13:30 -0400
                Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-15 18:07 +0000
                Re: Fast buffer idea Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-15 19:19 +0000
                Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-15 19:45 +0000
                Re: Fast buffer idea Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-16 08:33 +0000
                Re: Fast buffer idea Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-15 19:13 +0000
                Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-15 15:33 -0400
                Re: Fast buffer idea Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-16 08:16 +0000
                Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-16 22:10 -0400
                Re: Fast buffer idea Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-15 19:10 +0000
              Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-15 08:55 -0700
                Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-15 12:51 -0400
                Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-15 12:56 -0400
                Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-15 13:05 -0400
                Re: Fast buffer idea John Larkin <jjlarkin@highland_snip_technology.com> - 2017-05-15 10:28 -0700
                Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-15 13:38 -0400
                Re: Fast buffer idea John Larkin <jjlarkin@highland_snip_technology.com> - 2017-05-15 11:29 -0700
                Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-15 18:41 +0000
                Re: Fast buffer idea John Larkin <jjlarkin@highland_snip_technology.com> - 2017-05-15 13:19 -0700
                Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-15 20:46 +0000
                Re: Fast buffer idea John Larkin <jjlarkin@highland_snip_technology.com> - 2017-05-15 13:56 -0700
                Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-15 21:00 +0000
                Re: Fast buffer idea John Larkin <jjlarkin@highland_snip_technology.com> - 2017-05-15 16:46 -0700
                Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-16 01:22 +0000
                Re: Fast buffer idea John Larkin <jjlarkin@highland_snip_technology.com> - 2017-05-16 11:16 -0700
                Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-16 18:55 +0000
                Re: Fast buffer idea John Larkin <jjlarkin@highland_snip_technology.com> - 2017-05-16 12:21 -0700
                Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-16 20:33 +0000
                Re: Fast buffer idea John Larkin <jjlarkin@highland_snip_technology.com> - 2017-05-16 14:00 -0700
                Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-16 21:21 +0000
                Re: Fast buffer idea John Larkin <jjlarkin@highland_snip_technology.com> - 2017-05-16 16:15 -0700
                Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-16 23:58 +0000
                Re: Fast buffer idea John Larkin <jjlarkin@highland_snip_technology.com> - 2017-05-16 17:51 -0700
                Re: Fast buffer idea pcdhobbs@gmail.com - 2017-05-16 16:30 -0700
                Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-17 00:16 +0000
                Re: Fast buffer idea pcdhobbs@gmail.com - 2017-05-16 18:05 -0700
                Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-16 20:05 -0700
                Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-25 01:13 +0000
                Re: Fast buffer idea Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2017-05-24 21:43 -0400
                Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-30 03:16 +0000
                Re: Fast buffer idea Ralph Barone <ralph@invalid.com> - 2017-05-17 02:26 +0000
                Re: Fast buffer idea Gerhard Hoffmann <ghf@hoffmann-hochfrequenz.de> - 2017-05-17 08:34 +0200
                Re: Fast buffer idea Ralph Barone <ralph@invalid.com> - 2017-05-17 14:31 +0000
                Re: Fast buffer idea Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2017-05-17 10:39 -0400
                Re: Fast buffer idea Reinhardt Behm <rbehm@hushmail.com> - 2017-05-17 23:02 +0800
                Re: Fast buffer idea Gerhard Hoffmann <ghf@hoffmann-hochfrequenz.de> - 2017-05-16 21:24 +0200
                Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-16 20:12 -0700
                Re: Fast buffer idea Winfield Hill <hill@rowland.harvard.edu> - 2017-05-25 04:38 -0700
                Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-25 07:28 -0700
                Re: Fast buffer idea "Tim Williams" <tiwill@seventransistorlabs.com> - 2017-05-26 08:54 -0500
                Re: Fast buffer idea Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-26 14:14 +0000
                Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-26 07:21 -0700
                Re: Fast buffer idea "Kevin Aylward" <kevinRemovAT@kevinaylward.co.uk> - 2017-05-16 20:27 +0100
                Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-15 15:05 -0400
                Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-15 15:19 -0400
                Re: Fast buffer idea John Larkin <jjlarkin@highland_snip_technology.com> - 2017-05-15 13:21 -0700
                Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-15 20:56 +0000
                Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-15 17:37 -0400
              Re: Fast buffer idea "Kevin Aylward" <kevinRemovAT@kevinaylward.co.uk> - 2017-05-15 19:50 +0100
                Re: Fast buffer idea Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-15 19:25 +0000
                Re: Fast buffer idea "Kevin Aylward" <kevinRemovAT@kevinaylward.co.uk> - 2017-05-16 20:19 +0100
            Re: Fast buffer idea Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-15 14:33 +0000
              Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-15 13:15 -0400
                Re: Fast buffer idea Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-15 19:05 +0000
                Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-15 15:38 -0400
                Re: Fast buffer idea Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-16 08:12 +0000
                Re: Fast buffer idea Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-16 18:47 +0000
                Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-16 21:52 -0400
                Re: Fast buffer idea Winfield Hill <hill@rowland.harvard.edu> - 2017-05-25 05:05 -0700
                Re: Fast buffer idea pcdhobbs@gmail.com - 2017-05-25 05:42 -0700
                Re: Fast buffer idea Winfield Hill <hill@rowland.harvard.edu> - 2017-05-25 05:49 -0700
                Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-25 08:10 -0700
                Re: Fast buffer idea Gerhard Hoffmann <ghf@hoffmann-hochfrequenz.de> - 2017-05-25 15:01 +0200
      Re: Fast buffer idea "John Miles, KE5FX" <jmiles@gmail.com> - 2017-05-14 18:53 -0700
        Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-15 02:45 +0000
    Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-14 15:23 -0400
  Re: Fast buffer idea "Kevin Aylward" <kevinRemovAT@kevinaylward.co.uk> - 2017-05-14 20:28 +0100
    Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-14 16:00 -0400
    Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-14 16:10 -0400
      Re: Fast buffer idea Winfield Hill <hill@rowland.harvard.edu> - 2017-05-14 17:58 -0700
        Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-14 23:13 -0400
        Re: Fast buffer idea Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-05-16 17:27 -0700
          Re: Fast buffer idea Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-05-16 17:34 -0700
      Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-14 20:14 -0700
        Re: Fast buffer idea "Kevin Aylward" <kevinRemovAT@kevinaylward.co.uk> - 2017-05-15 19:42 +0100
  Re: Fast buffer idea "Tim Williams" <tiwill@seventransistorlabs.com> - 2017-05-16 03:29 -0500
    Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-16 06:57 -0700
      Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-16 22:47 -0400
        Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-16 20:18 -0700
          Re: Fast buffer idea "Tim Williams" <tiwill@seventransistorlabs.com> - 2017-05-17 02:22 -0500
    Re: Fast buffer idea Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-16 14:05 +0000

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