This particular melody generator is founded on an integrated CMOS Schmitt Trigger reference circuit 4093. It could be utilized in alarms, doors and cars (as an example when driving a vehicle in reverse).
Three among the the four gates of the NAND 4093 are hooked up in series via RC networks. The oscillation is impacted by feedback from the output of N4 to input N2. The high logics created by the cascaded gates, contained in the oscillator circuit, are accustomed to adapt one of the associated diodes (D1, D2 or D3). Let's imagine the diode links one of the capacitors which establishes the frequency (C1 to C3) to the tone oscillator N1. The sound signal becomes accessible whenever S1 is pushed and is ascribed to the couple of complementary transistors (T1, T2) which activate the loudspeaker. The frequency of the emitted musical signal could be tweaked whenever P1 is shoved.