What to buy: Potentiometers (variable resistor), buttons, capacitors (electrolytic capacitors longer leg is to connect to the positive end, poly film capacitors),

to charge 63% of capacitors,

diodes, LED is one type of diodes, ideal diodes only allow the flow in schematic symbol, if install it properly, called forward bias, reversely, called reverse bias. there is voltage limit, if pass it, called breakdown.it also requires proper voltage drop to allow current flow through. it helps prevents if improper installed wiring.

Relays, NPN or PNP, Relay Oscillator and Speaker, Integrated circuits (IC): 555 timer

There are astable, bistable and monostable mode in triple 5 timer. An integrated circuit (IC), often referred to as a chip or microchip, is a set of electronic circuits on a small flat piece (or “chip”) of semiconductor material, usually silicon. The integration of a large number of tiny transistors into a small chip results in circuits that are orders of magnitude smaller, faster, and less expensive than those constructed of discrete electronic components. The IC’s mass production capability, reliability, and building-block approach to integrated design has ensured its continued adoption for a vast array of applications.

The 555 timer IC is one of the most popular and versatile integrated circuits ever produced. It is widely used in electronic circuits and projects to generate time delays, as an oscillator, and as a flip-flop element. Introduced in the early 1970s by Signetics, the 555 timer is still widely available and used due to its ease of use, reliability, and low cost.