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From: Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net>
Newsgroups: sci.electronics.design
Subject: Re: Designs
Date: Thu, 9 May 2024 02:31:11 -0000 (UTC)
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Edward Rawde <invalid@invalid.invalid> wrote:
> "john larkin" <jl@650pot.com> wrote in message 
> news:imvn3jt2fmc579svih93qvj54o41rabc60@4ax.com...
>> On Wed, 8 May 2024 20:10:48 -0000 (UTC), jim whitby
>> <news@spockmail.net> wrote:
>> 
>>> Somebody neds to post a design... so here's one!
>>> 
>>> https://imgs.xkcd.com/comics/circuit_diagram.png
>> 
>> https://www.dropbox.com/s/w8px8z9mf64wpc9/HVamp.JPG?raw=1
>> 
> 
> Reminds me of audio amps which used an op amp's supply pins for the upper 
> and lower drive. 
> 
> 
> 

That’s a pretty mainstream technique actually.  It’s a lot easier to
stabilize if the op amp has good supply rejection—lots don’t, especially on
the negative side. 

In the last dozen years or so, AD and TI have come out with a lot of great
36V op amps, but for several years before that, they were dropping lots of
good old HV parts such as the LF357 and AD743  , and only introducing 5-V
ones.  Using the supply pins to drive a Class B output stage lets you use
LV parts for higher-voltage applications. 

Cheers 

Phil Hobbs 

-- 
Dr Philip C D Hobbs  Principal Consultant  ElectroOptical Innovations LLC /
Hobbs ElectroOptics  Optics, Electro-optics, Photonics, Analog Electronics