This the circuit warns the trespasser infrared system or Infrared Intruder Alarm circuit that interesting. By when there is a person passes or cut the light infrared. The system will clearly warn immediately, command give relay work, build current give super siren or The other , this circuit then suit is burglar alarm circuits. When see the equipment the a few compose IC 555 perform produce the frequency drives LED infrared in a part sends. The part takes as a result have photo diode perform take the light infrared. Then transmit transistor for boost up a signal gives the power goes up , and change double voltage be 2 times. Before change IC CA3130 op-amp circuits perform compare with voltage model the turned around. Be when have no a signal reaches that outgoing have high voltage come out. But seek have usual signal have no current come out give BC109 drive relay get. The detail is other see in the circuit.