Musical car reverse horn circuit

Here is a simple circuit that will produce a musical horn when ever your car is in reverse gear.The circuit uses two ICs for the operation ,voltage regulator 7805(IC1) and musical tone generator UM66(IC2).The IC1 reduces the car battery voltage to 5V.The diodes D1 & D2 in combination produces an additional drop of 1.4 V to give a 3.6 V supply for the UM66.The supply voltage of UM 66 should not be