I'm trying to design a motion sensor alarm. If there is movement in my house, the motion sensor will send out a signal which will be connected to an alarm that will make a loud noise. I'm currently trying to pick the right motion sensor(ZRE200GE) and I found this https://http://www.zilog.com/docs/PS0336.pdf.
The output signal is described as Measurement Amp.: Non-inverted type, gain 72.5 dB at 1 Hz, 0.4 to 2.7 Hz／-3 dB
I'm really not familiar with DB stuff. But a google search showed me that 72.5db is equivalent to 4216.96 Voltage ratio which is something I'm very skeptical about (Too high of a gain). Is this conversion correct? Here is the recommended circuit from the sensor datasheet:
Here's what I have so far. My gain is 2 which should give an output voltage of 10V if I power the sensor by 5V, and my cutoff frequency is 1Hz. Here V1 is the sensor that outputs 5V like a sensor. Is there any fault in my design?
Note: This design is based on the assumption that when there is movement, the sensor turns on the FET which will connect the Drain and Source, hence opamp would also get 5V(roughly, of course, ignoring voltage drop across FET).