Pin Receptacle Housing, Rectangular connector housing, plastic connector,

 DT Series 6 Position Three Row Female Socket Free Hanging Plug Housing

https://www.futureelectronics.com/p/interconnect--rectangular-connectors/dt06-6s-te-connectivity-5076065

What is an 8 bit microcontroller, Embedded microcontrollers, lcd microcontroller

 PIC18F Series 32 kB Flash 2 kB RAM 40 MHz 8-Bit Microcontroller - TQFP-64

https://www.futureelectronics.com/p/semiconductors--microcontrollers--8-bit/pic18f6520-i-pt-microchip-7337520

Oscillators timing device, through hole oscillators, ceramic oscillator

 50MHz ±50ppm 50pF HCMOS/TTL 55% 3.3V 4-Pin SMD Oscillator

https://www.futureelectronics.com/p/electromechanical--timing-devices--oscillators/cb3lv-3c-50m000000-cts-5629860

What is optocoupler isolation, Optocouplers applications, high-voltage circuit

 PS2501 Series Single Channel 80 Vce 5000 Vrms SMT Photocoupler - DIP-4

https://www.futureelectronics.com/p/semiconductors--optoelectronics--isolation-components-optocouplers/ps2501l-1-f3-a-renesas-1397785

Standard Tantalum Chip Capacitor, Electrolytic capacitor, 1uf tantalum capacitor

 TAJ Series 10 uF ±10% 16 V Surface Mount Standard Tantalum Chip Capacitor

https://www.futureelectronics.com/p/passives--capacitors--tantalum-capacitors/taja106k016rnj-kyocera-avx-7015456

What is Demultiplexer, Multiplexers programming, multiplexer truth table

 Single 16 Channel 5 to 20 V 50 Ω CMOS Analog Multiplexer - PLCC-28

https://www.futureelectronics.com/p/semiconductors--analog--multiplexer-demultiplexer/dg406dn-t1-e3-vishay-3148293

References, step-down switching regulator, what is a switching regulator

 MP2456 Series 50 V 0.5 A 1.45 MHz Surface Mount Step-Down Converter - TSOT23-6

https://www.futureelectronics.com/p/semiconductors--analog--regulators-reference--switching-regulators/mp2456gj-z-monolithic-power-systems-4045646