This 4093 Drone Synth is a very detailed and fun synth to build and mess with.  4 onboard 555 timers control the 4093 Nand IC to create otherworldly sounds.  The switches control which 555 timers are functioning  at one time: one to four, in any combination prove to make this kit highly versatile.  The Pots control the droning frequency of pulse of the 4093.  This design allows for both CV and Clock inputs, adding yet more functionality and creativity.  One of the nicest synths we make! Kits include wire, not pictured.  PCB Measures: 3.1875 X 3.375″