74HC151 An 8-Digit Multiplexer IC (74151 IC) DIP-16 Package CD4017 Because the PMBT3904 is an

Because the PMBT3904 is an NPN transistor

20A @125V AC Switching Mode ON-ON Structure DPDT Type Locking Material Plastic and Metal  Dimension(LxWxH) 31x25

These are Carbon Film Resistor with a value of 18 ohm 1/2W and tolerance of ±5%

Resistance 150 ohm (151) Brand Resistor Chip size 0805 Tolerance 5% Power 1/8W Temperature Range -55°C to +125°C Mounting Type Surface mount No

then do not release the first button，just release the second button

74HC151 An 8-Digit Multiplexer IC (74151 IC) DIP-16 Package CD4017 Because the PMBT3904 is an74HC series ICs are High speed logic gates with very low power consumption that utilize advanced silicon gate CMOS technology and 74HC151 is one of them. It has balanced propagation delay and transition times. 74HC151 ICs contain a single 8 channel digital multiplexer with binary control input A, B, and C and an Active Low enable input. These three inputs can select the 1 to 8 output line. 74HC151 ICs provide inverting and non inverting output. The