PIR or Passive Infrared is a commonly used sensor to detect human presence. This application is used for system alarms in homes or offices. These sensors work processes carried out by detect human body heat radiation is converted into a change voltage.
But change is very small voltage on the PIR that is centered on the order
10 to 20 milivolt or even smaller. It really depends from several factors namely, the heat from the human body are detected, the distance sensor with and ambient temperature. Therefore we need non-inverting amplifier circuit first amplifier like in the picture
Strengthening of existing in the existing Non-inverting amplifier in this picture
can be determined by the following formula:
A = Rf / Ri
= 1M/10K
= 100x
Users can set the value of Rf and Ri by turning the variable resistor
1M and 10K that existed at the OP-2001 Module So that the voltage swing can be detected by the microcontroller or other digital circuits, it is necessary to be a comparator changing the voltage swing is a condition of logic 0 and 1.
Voltage swings are not always occur at the same voltage value.
This means that as an example for a swing of 0.2 volts can occur at a stress 3.8 volts to 4 volts, or may also at 3 volts to 3.2 volts and others. This will
difficult part in determining the voltage comparator.
In order for this voltage swing is always in the same position, then the DC level of This signal can be eliminated by using a capacitor as shown in
picture below. Capacitor will block DC voltage so that only the voltage swing
Just coming into the input of the comparator
To set the module into a series of OP-01 Non-inverting amplifier then forwarded to a comparator which follows the following figure shows the use of an Op Amp as a non inverting amplifier and two Op Amp as a comparator.
