Heart Rate Sensor Circuit

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jprovost12

Joined Oct 18, 2019
5
I understand the majority of this circuit, but could anyone explain to me why there is +2.5V connected to the non-inverting terminal on the first and last op-amps? In my classes, we've always connected this to ground when using an inverting configuration.
 

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Alec_t

Joined Sep 17, 2013
11,739
In my classes, we've always connected this to ground when using an inverting configuration.
That applies if your opamp has dual polarity supplies, e.g.+5V and -5V. If the opamp has ony a single polarity supply, say +5V, then it is common practice to provide a 'virtual ground' at half the supply voltage, i.e +2.5V.
 
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