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I have a sensor which generates signal in range of 240mV to 940mv. Now, I use amplifier of voltage for my sensor, which generates output signal in range 350mV to 1000mV. I used rail-to-rail operational amplifier.

schematic

simulate this circuit – Schematic created using CircuitLab

But I need switch which can quickly toggle between original signal and signal amplifier. Switch must act quickly, because signal below 240mV is not allowed and signal above 1000mV is also not allowed.

Additionally, I have one +12V signal that I can use to control of switch.

How do I design switch for this circuit?

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    \$\begingroup\$ I'm not sure what you are trying to do. You could look into analog switches. (Those diodes in the signal path will change the output voltage.) \$\endgroup\$ – George Herold Oct 27 '14 at 14:54
  • \$\begingroup\$ I have input signal from sensor in range of 240mV to 940mV. Next, I have a amplifier that generates output signal in range of 350mV to 1000mV. And, I need switch which switching between two signal (original 240mV-940mV or amplifier 340mV-1000mV) \$\endgroup\$ – Heniek Kowalski Oct 27 '14 at 15:15
  • \$\begingroup\$ OK a comparator to sense your "switch point" and an analog switch to do the switching. My point is that the diodes will drop ~500 mV or so depending on how much current is being drawn by the output. \$\endgroup\$ – George Herold Oct 27 '14 at 15:58
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Put the switch on the output and you won't need the diodes. A CD4053 Triple 2-channel analog multiplexor will do the job (you could use it to switch both the input and output if you wish, though this shouldn't be necessary).

Alternatively you could just switch the amplifier gain down to +1, and then it will pass the signal through unamplified.

enter image description here

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