Smoke Detectors
Components:
TWO electrodes(Positive Electrode, Negative Electrode) ,Americium 241 (Radioactive material , Alpha Source )(0.29 micrograms),Black Cylinder,MOSFET(sense the change in current),9 volt battery
Operation:
There was a black cylinder that covers overall miniature equipment like electrodes, Radioactive material, MOSFET. Allows the air to pass through it. Air doesn't conduct electricity but the Radioactive material Americium which atomic number : 95, Atomic weight : 243.1 acts as a source that makes the oxygen and nitrogen ions in air between the positive electrode and negative electrode to made the electrons active and it is driven by a voltage source of 9 volt causes some current in the range of 100 pico amps When smoke enters the chamber the ions attach to it and slow down and often lose their charge, both events cause the current to stop, which triggers the alarm. In the circuit we use 9 volt battery for creating voltage difference between gate and drain. Drain of MOSFET connected with horn . Flow of current from source to drain due to triggering gate make the horn due to flow of current. Then after the air inside electrode produces tiny current as said as above goes through a large resistor produces voltage according to V=IR ohm's law. This voltage opposes the battery and it shut down the flow of current through the MOSFET.
Again smoke enters the same above operation will happen.
Below the Overall Circuit Shown.......
