Simple Provide Remote Alarm for Smoke Detector Circuit

Here’s a design circuit for an application from Maxim Semiconductor Application Notes. Nowadays, due to efficiency and low cost, ionization-based smoke detector are often installed in the buildings, houses, and garages. The device is placed far away from the house. Therefore, we need to transmit the alarm signals back into the central security system. This is the figure of the circuit;

The Integrated Circuit MAX921 is used as a comparator. The properties of this IC are have low supply current, internal voltage reference, and wide supply-voltage range. The typical value of currents are 50uA during monitor mode. When the sounder is active, the value of the current is 3mA. This circuit gains power from the smoke detector’s battery. This circuit has an output of an open-drain FET, which will trigger an RF module that communicates or drive the home-security system back to the residence.