This circuit named ultrasonic radar, where this circuit can in applying at security system house and or other security and safety system. in principle this circuit consisted of transmitter and receiver which transmitter and receiver can work with the same frequency, if both having different frequency hence this circuit cannot work. For circuit transmitter is given in symbol T, which frequency yielded by two NAND gates, causing yields signal multi vibrator, this signal which will be sent by transmitter then bound signal from transmitter in comparing to signal which in yielding by receiver, at receiver in symbol R. which entering signal strengthened by TR3 and strengthened again by IC OP-Amp 741. The signal from Op-Amp then returned by IC 2 here signal compared to which then is sent to which NAND gate if happened difference of frequency hence will activate TR1 and TR2 for in attributing to siren or indicator lamp.
