Source: https://mokxi.com/learn/path/electronics-basics Updated: 2026-11-11 All paths # Electronics basics A breadboard and a few parts, with one Uno blink at the start and no processor after it. What current, voltage, time and logic really do. Free 20 lessons 10 h 11 chapters 4,140 XP Electrical ยท Beginner +100 XP 0 of 20 done Start the course free Build your first circuit Lesson plan for teachers What you will build ## 6 projects, built step by step 20 lessons in 11 chapters, about 10 hours on a simulated breadboard. Free, in your browser, every step checked by the simulator. Chapter 1 project ### The switch, and what open really means A slide switch in the middle of a loop. Find out what a break in a circuit does, why the switch can go anywhere in it, and what a floating wire is. Open it in the simulator Chapter 3 project ### Branches in parallel Two LED branches across the same supply. Each one sets its own current, the supply carries the total, and two resistors side by side come out smaller than either. Open it in the simulator Chapter 4 project ### A light sensor is a divider that moves A light-dependent resistor changes its resistance with light. Put it in a divider and the voltage tells you how bright the room is. Open it in the simulator Chapter 5 project ### Choosing R and C for a delay you want The same circuit, used the other way around: start from the delay, pick the parts, and find out which of the two you should change. Open it in the simulator Chapter 9 project ### The 555 with a reset pin The same astable, gated by a button on the reset pin instead of switched in the supply, driving a buzzer. Why gating a chip beats switching a load. Open it in the simulator Chapter 10 project ### Flip-flops that count A D flip-flop wired to toggle halves a clock. Four of them in a chain count in binary, and the lamps spell out the number. Open it in the simulator The map ## Chapter by chapter Each lesson opens when the one before it is done, and each chapter ends in a project. Chapter 1 ## The first loop Wire a loop by hand, let an Uno blink it, then read a circuit as a loop and light an LED on purpose. Open 165 XP ### Build your first circuit Start with the parts in place. Draw every wire yourself, close the loop, press Run and light the LED. 0 of 5 steps Start What is in it Locked 140 XP ### Make it blink with an Uno Two wires from an Arduino Uno to the LED you already know, then press Run and let a program do the switching. Four steps, no code to write. 0 of 4 steps Locked 160 XP ### A first circuit One loop on a breadboard: five volts, a pushbutton, a resistor and an LED. Build the habit of reading a circuit as a loop, and work out the current in it. 0 of 6 steps Project Locked 340 XP ### The switch, and what open really means A slide switch in the middle of a loop. Find out what a break in a circuit does, why the switch can go anywhere in it, and what a floating wire is. 0 of 7 steps 5 questions, graded as you go. Chapter 2 ## Ohm's law Volts, amps and ohms in one equation, and how to use it backwards to pick a part. Locked 160 XP ### Ohm's law: volts, amps and ohms One resistor across 5 V. Change the resistor and watch the current change, then pick a resistor for a current you want. The one equation behind every circuit. 0 of 6 steps 4 questions, graded as you go. Chapter 3 ## Series and parallel The two ways to join parts, and the sums that go with each. Locked 170 XP ### Resistors in series Two resistors nose to tail with an LED. One current everywhere, resistances that add, and voltages that share themselves out in proportion. 0 of 7 steps Project Locked 340 XP ### Branches in parallel Two LED branches across the same supply. Each one sets its own current, the supply carries the total, and two resistors side by side come out smaller than either. 0 of 7 steps 5 questions, graded as you go. Chapter 4 ## Dividers and sensors Split a voltage in a ratio you choose, then let a light sensor move the ratio. Locked 160 XP ### The voltage divider Two resistors in a row split a voltage in a fixed ratio. Read the middle with a meter, change the ratio, and build a divider for a voltage you choose. 0 of 6 steps Project Locked 320 XP ### A light sensor is a divider that moves A light-dependent resistor changes its resistance with light. Put it in a divider and the voltage tells you how bright the room is. 0 of 6 steps 4 questions, graded as you go. Chapter 5 ## The capacitor and RC timing A part that takes time, and how to choose how much time it takes. Locked 170 XP ### Charging a capacitor A resistor, a capacitor and a switch. Watch a voltage take time to get somewhere, and learn the one number that says how long. 0 of 7 steps Project Locked 370 XP ### Choosing R and C for a delay you want The same circuit, used the other way around: start from the delay, pick the parts, and find out which of the two you should change. 0 of 7 steps 5 questions, graded as you go. Chapter 6 ## The transistor switch A trickle into one leg switches a much bigger current through the other two. Locked 145 XP ### The transistor as a switch A tiny current into the base switches a big current through the collector. Switch an LED with a transistor and measure how much smaller the control current is. 0 of 6 steps 4 questions, graded as you go. Chapter 7 ## Power from the wall Four diodes and a capacitor turn the wall's AC into steady DC. Locked 135 XP ### From the wall to DC: a rectifier and a capacitor One diode blocks the negative half of an AC wave, and a big capacitor fills the gaps. Watch AC turn into smooth DC, and see what a small capacitor or a heavy load does to it. 0 of 5 steps 4 questions, graded as you go. Chapter 8 ## The op-amp Two resistors set the gain of an amplifier, and the supply sets how far it can go. Locked 110 XP ### The op-amp: a gain you can choose Two resistors set the gain of an inverting op-amp amplifier. Turn a tiny wave into a big one, then push the gain until the top and bottom get chopped flat. 0 of 4 steps 4 questions, graded as you go. Chapter 9 ## The 555 Turn an RC into a square wave, and gate it with a button. Locked 160 XP ### Timing with no processor: the 555 A resistor, a capacitor and a 555 make a square wave with no code in sight. Measure it, then change the parts to change the rate. 0 of 6 steps Project Locked 370 XP ### The 555 with a reset pin The same astable, gated by a button on the reset pin instead of switched in the supply, driving a buzzer. Why gating a chip beats switching a load. 0 of 7 steps 5 questions, graded as you go. Chapter 10 ## Logic gates and a latch Decisions in nanoseconds, one bit of memory, and four flip-flops that count. Locked 145 XP ### Gates, as real chips AND, XOR and NOT with two buttons and three lamps. Fill in the truth tables by pressing, and find out what a real chip has that the symbol does not. 0 of 6 steps Locked 145 XP ### One bit of memory Two NAND gates wired into each other hold an answer after the input goes away. The smallest memory there is, and the reason a switch stops bouncing. 0 of 6 steps Project Locked 290 XP ### Flip-flops that count A D flip-flop wired to toggle halves a clock. Four of them in a chain count in binary, and the lamps spell out the number. 0 of 6 steps 5 questions, graded as you go. Chapter 11 ## The shift register Three wires in, eight outputs out, and as many more as you chain on. Locked 145 XP ### Eight outputs from three wires A 74HC595 driven by a clock and a switch, with no processor anywhere. Load a pattern by hand, watch it march, and find out what the latch is for. 0 of 6 steps 4 questions, graded as you go. Syllabus ## Every lesson in the course All 20 lessons, in order, each with what it covers. Any of them opens in the editor right away. Chapter 1 ### The first loop - Build your first circuit Start with the parts in place. Draw every wire yourself, close the loop, press Run and light the LED. - Make it blink with an Uno Two wires from an Arduino Uno to the LED you already know, then press Run and let a program do the switching. Four steps, no code to write. - A first circuit One loop on a breadboard: five volts, a pushbutton, a resistor and an LED. Build the habit of reading a circuit as a loop, and work out the current in it. - The switch, and what open really means A slide switch in the middle of a loop. Find out what a break in a circuit does, why the switch can go anywhere in it, and what a floating wire is. Chapter 2 ### Ohm's law - Ohm's law: volts, amps and ohms One resistor across 5 V. Change the resistor and watch the current change, then pick a resistor for a current you want. The one equation behind every circuit. Chapter 3 ### Series and parallel - Resistors in series Two resistors nose to tail with an LED. One current everywhere, resistances that add, and voltages that share themselves out in proportion. - Branches in parallel Two LED branches across the same supply. Each one sets its own current, the supply carries the total, and two resistors side by side come out smaller than either. Chapter 4 ### Dividers and sensors - The voltage divider Two resistors in a row split a voltage in a fixed ratio. Read the middle with a meter, change the ratio, and build a divider for a voltage you choose. - A light sensor is a divider that moves A light-dependent resistor changes its resistance with light. Put it in a divider and the voltage tells you how bright the room is. Chapter 5 ### The capacitor and RC timing - Charging a capacitor A resistor, a capacitor and a switch. Watch a voltage take time to get somewhere, and learn the one number that says how long. - Choosing R and C for a delay you want The same circuit, used the other way around: start from the delay, pick the parts, and find out which of the two you should change. Chapter 6 ### The transistor switch - The transistor as a switch A tiny current into the base switches a big current through the collector. Switch an LED with a transistor and measure how much smaller the control current is. Chapter 7 ### Power from the wall - From the wall to DC: a rectifier and a capacitor One diode blocks the negative half of an AC wave, and a big capacitor fills the gaps. Watch AC turn into smooth DC, and see what a small capacitor or a heavy load does to it. Chapter 8 ### The op-amp - The op-amp: a gain you can choose Two resistors set the gain of an inverting op-amp amplifier. Turn a tiny wave into a big one, then push the gain until the top and bottom get chopped flat. Chapter 9 ### The 555 - Timing with no processor: the 555 A resistor, a capacitor and a 555 make a square wave with no code in sight. Measure it, then change the parts to change the rate. - The 555 with a reset pin The same astable, gated by a button on the reset pin instead of switched in the supply, driving a buzzer. Why gating a chip beats switching a load. Chapter 10 ### Logic gates and a latch - Gates, as real chips AND, XOR and NOT with two buttons and three lamps. Fill in the truth tables by pressing, and find out what a real chip has that the symbol does not. - One bit of memory Two NAND gates wired into each other hold an answer after the input goes away. The smallest memory there is, and the reason a switch stops bouncing. - Flip-flops that count A D flip-flop wired to toggle halves a clock. Four of them in a chain count in binary, and the lamps spell out the number. Chapter 11 ### The shift register - Eight outputs from three wires A 74HC595 driven by a clock and a switch, with no processor anywhere. Load a pattern by hand, watch it march, and find out what the latch is for. Keep going ## The next course on your track Electronics basics is part of the electrical track, a ladder of courses from zero to expert. Next course ### Digital logic and memory Build logic from individual gates, then make a bit persist, count and move through a register. Open the next course Track ### Electrical track Current and voltage you can see, then transistors, op-amps, filters, power and PCBs. Every circuit runs in a real circuit simulator in your browser. See every course on the track Kits ## Build it on your bench too Every lesson runs in the simulator with nothing to buy. When you want the real thing, these kits have the parts. Have a kit already? ### Find your kit Pick the starter kit you own and run every lesson in its manual with the same parts on the same pins. See every kit Questions ## About Electronics basics Is Electronics basics free? Yes. All 20 lessons of Electronics basics are free and run in your browser, with nothing to install and no parts to buy before you start. Do I need any parts? No. Every circuit is built on a simulated breadboard, and the simulator checks each step as you go. When you want to build it for real, the same parts and wiring work on a real bench. How long does Electronics basics take? About 10 hours: 20 lessons in 11 chapters, each one a few short steps. Your progress is kept, so you can stop after any lesson and pick up where you left off. What will I build? Each chapter ends in a project that puts it together: The switch, and what open really means, Branches in parallel, A light sensor is a divider that moves, Choosing R and C for a delay you want, The 555 with a reset pin and Flip-flops that count. Where do I start? With "Build your first circuit". This course starts from zero: no electronics or code needed before it.