Tricky Circuit

First Spark · Tricky Circuit

Learn electronics from zero

54 interactive electronics lessons, 162 challenges and three difficulty levels in eleven languages. Learn how components interact through experiments and a searchable Circuitpedia.

First circuits

  1. 1

    Make light obey.

    LED + resistor

  2. 2

    One path, two resistors

    R1 + R2

  3. 3

    Give current a choice

    R1 ∥ R2

  4. 4

    A knob becomes a voltage

    10 kΩ

  5. 5

    A resistor has a heat budget

    Power and component ratings

  6. 6

    Why a battery sags

    Internal resistance and useful power

Read the world

  1. 7

    Divide the invisible.

    Two resistors + load

  2. 8

    Light becomes a signal.

    LDR + resistor

  3. 9

    A circuit feels temperature

    NTC + R

  4. 10

    Give a button a definite answer

    Pull-up resistor and digital input

  5. 11

    A bridge that notices tiny changes

    Two dividers, one difference

Control a circuit

  1. 12

    A one-way gate for current

    D + R

  2. 13

    A small signal takes control.

    NPN + LED

  3. 14

    Dim a light by switching quickly

    Pulse width and average current

  4. 15

    Switch a load with an electric field

    Gate, source and drain

  5. 16

    A diode that holds a voltage

    Zener clamp and current budget

  6. 17

    Build a decision with two switches

    The NAND logic gate

Signals and time

  1. 18

    Catch time in a circuit.

    Resistor + capacitor

  2. 19

    Turn a voltage into a number

    Resolution and quantization

  3. 20

    Let slow changes pass

    A resistor–capacitor low-pass filter

  4. 21

    Let fast changes through

    A resistor–capacitor high-pass filter

  5. 22

    A coil resists sudden current changes

    Magnetic energy in an RL circuit

  6. 23

    Tune a circuit like a musical note

    Resonance in a series RLC circuit

  7. 24

    Make a timer blink by itself

    The 555 astable oscillator

  8. 25

    Give one press a timed response

    A 555 monostable pulse

Combine your skills

  1. 26

    Protect a divider from its load

    A voltage-follower buffer

  2. 27

    Amplify a signal and flip it

    An inverting operational amplifier

  3. 28

    Make a small signal taller

    A non-inverting operational amplifier

  4. 29

    A night-light that remembers

    Light sensing and hysteresis

  5. 30

    Turn both halves of a wave upright

    A four-diode full-wave bridge

Decisions and memory

  1. 31

    A voltage that makes a decision

    Comparator: below, equal, above

  2. 32

    A decision that remembers

    Schmitt trigger and two thresholds

  3. 33

    The coil keeps going after switch-off

    Relay coil and its flyback diode

  4. 34

    Teach a circuit to remember

    A one-bit SR latch

  5. 35

    Turn four bits into a voltage

    A four-bit R–2R DAC

  6. 36

    Count events with four lights

    A binary counter and clock divider

Logic that calculates

  1. 37

    Spot the difference with XOR

    The gate that notices disagreement

  2. 38

    Make a tiny binary calculator

    Half adder: sum and carry

  3. 39

    Pass the carry to the next place

    Full adder: three inputs, two answers

  4. 40

    Choose which signal gets through

    MUX: a controlled crossroads

  5. 41

    Turn an address into one chosen line

    Two-bit decoder and one-hot output

  6. 42

    Add one bit to spot some errors

    Even parity and its blind spot

Analog signal workshop

  1. 43

    Mix two signals with resistors

    An inverting summing amplifier

  2. 44

    Keep the difference, reject the shared part

    A matched difference amplifier

  3. 45

    Let voltage accumulate with time

    An inverting integrator

  4. 46

    Measure how quickly a signal changes

    A ramp differentiator

  5. 47

    Freeze a measurement, then watch it fade

    Sample and hold with passive leakage

  6. 48

    Detect the safe middle

    A window comparator

Motion, sound and communication

  1. 49

    Steer a shaft with time

    Servo: a tiny timing command

  2. 50

    Turn counted steps into motion

    Stepper: commands with a direction

  3. 51

    Build a tone from two levels

    Frequency, pulse shape and pitch

  4. 52

    Measure with an echo

    Ultrasonic time of flight

  5. 53

    Notice a tiny resistance imbalance

    The Wheatstone bridge

  6. 54

    Turn a byte into a timed message

    UART: an 8N1 frame

EXPERIMENT BENCH

Change the circuit settings, predict the readings, then check a challenge. These are learning models, with the assumptions explained in each lesson.

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