[sdiy] Buffered question

[David G Dixon]

"Opamp buffer circuits aren't just for supplying current, they are also for
providing low output impedances."

Same dif?





It's not always the circuit.  Some opamps - such as low power varieties -
have weak current outputs.

MC

On 12/29/20, David G Dixon <dixon at mail.ubc.ca> wrote:
> Most of the common opamp circuit configurations also act as buffers.  
> What that means is that the opamp will supply as much current as is 
> required to maintain the desired voltage regardless of the downstream
impedance.
>
> However, if there is something like a diode inbetween the opamp's 
> output and the destination, then you have to be very careful.  For 
> example, the classic two-diode opamp rectifier does not buffer, and 
> must be followed with a buffer generally.  This is one of those areas 
> where it is easy to make a design mistake, and then when your design 
> doesn't do exactly what it is supposed to, you have a 
> forehead-slapping moment when you realize that you have 
> inappropriately taken opamps for granted.
>
>
>
>   _____
>
> From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On Behalf Of 
> Kristian Blåsol
> Sent: Tuesday, December 29, 2020 6:41 AM
> To: synth-diy mailing list
> Subject: [sdiy] Buffered question
>
>
> [CAUTION: Non-UBC Email]
> Hello,
>
> A question about opamp buffers or voltage followers. So one of those 
> circuits makes sure that whatever you plug in to the output of the 
> buffer wont affect whatever you have on the input of the buffer... right?
>
> But there are so many different circuits you can make with an opamp, 
> is there any of those that in itself IS a buffer, or do ALL other 
> opamp circuits need buffering after it for the output to not affect the
input?
>
> For example: a comparator, isnt that already buffered in itself? Since 
> the output is either ground or +v?
>
> And how about a mixer/summing amplifier, op-amp as an amplifier, high 
> and low pass filters.
>
> Im thinking so I dont put a buffer on an already buffered signal... :)
>
> Thanks in advance,
> /Kristian
>
>
>
> --
>
> ---
> Kristian Blåsol
>
>