Soldering Practice Kit Learn to Solder Kits DIY Electronic Soldering Project Learning Board

After power-on NE555 and peripheral circuits form a multivibrator. The oscillation frequency is mainly determined by R1 RP and C2. Adjusting RP can change the oscillation frequency. The oscillation signal of the oscillator is output from pin 3 of NE555 and sent to the counting input of CD4017. (14 feet) every time a pulse arrives the high level output by Q0-9 of the counter moves 1 bit in turn lighting up the corresponding light-emitting diode thus producing the feeling of running water. Among them L11 is connected to the counting output terminal C0 of 4017. When L1-5 is lit the C0 terminal of 4017 outputs a high level and lights up L11. When L6-10 is lit the C0 terminal outputs a low level and L11 does not light up. If you feel that L11 is unsightly you can also not install it and it will not affect the circuit work at all.