RE46C190 photoelectric smoke detector circuit design

Using RE46C190 photoelectric smoke detector circuit can be designed a very simple and low power smoke detector alarm project..
With minimal external components, this smoke detectors alarm circuit will provide all the
required features for a photoelectric smoke detector type electronic project .The design incorporates a gain-selectable photo amplifier for use with an infrared emitter detector pair.
An internal oscillator strobes power to the smoke detection circuitry every 10 seconds, to keep the standby current to a minimum. If smoke is sensed, the detection rate is increased to verify an Alarm condition.
This photoelectric smoke detector circuit type smoke detector alarm will check for a low battery condition every 86 seconds, and chamber integrity is tested once every 43 seconds, when in Standby.
Pin nr 12 us an interconnect pin that allows multiple detectors to be connected such that, when one unit alarms, all units will sound (using pin 12 pin you can create a smoke detector alarm circuit for many rooms ).