differential amplifier

crutschow

Joined Mar 14, 2008
25,122
Apparently the circuit is to detect a light signal, so there would be a second circuit like the top circuit just to detect the ambient light (background) to make it easier to separate the signal light from the background light.
 

Thread Starter

dark123

Joined Feb 25, 2020
3
Apparently the circuit is to detect a light signal, so there would be a second circuit like the top circuit just to detect the ambient light (background) to make it easier to separate the signal light from the background light.
where should I connect that part as a link?
 

Hymie

Joined Mar 30, 2018
836
I would venture that the BACK GND signal fed to the differential amplifier (via R2) is generated from an identical circuit as the components around U1A, except that the sensor ‘PD1’ is sensing the background light level.
 
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