Resistor
Limits the current in a circuit. Measured in ohms (Ω). European (IEC) drawings often show it as a plain rectangle instead.
Quick fire
Pick a mode
- You have 3 fuses. A wrong answer or a timeout blows one.
- Fast answers earn bonus points. Every 3 in a row raises your multiplier, up to ×4.
- The clock starts at 10 seconds and shrinks to 5 as you go.
Enter to start · keys 1–4 to answer
Name this symbol
All fuses blown · Game over
0 points
New best score
Wire up
Connect each symbol to its name
Tap a symbol, then its name. The clock starts on your first tap, and each wrong connection adds 5 seconds.
Legend
Every symbol in the game
The letter in the corner is the reference designator printed next to the part on a real schematic, like R1 or C4.
Variable resistor
The diagonal arrow through the body means the resistance can be adjusted, as in a rheostat or trimmer.
Potentiometer
Three terminals. The arrow is a sliding wiper that taps off part of the voltage. Volume knobs are usually pots.
Light-dependent resistor (LDR)
Its resistance falls as light gets brighter. Arrows pointing in mean light falls on the part.
Capacitor
Two plates separated by an insulator store charge. Measured in farads (F); real parts are usually µF, nF or pF.
Polarized capacitor
Electrolytic capacitors have a + side and must be connected the right way round, or they can fail.
Inductor
A coil of wire that stores energy in a magnetic field and resists changes in current. Measured in henries (H).
Transformer
Two coils on a shared iron core step AC voltage up or down. The parallel lines between the coils show the core.
Fuse
A thin link that melts and opens the circuit when too much current flows. Your lives in this game are fuses.
Crystal oscillator
A slice of quartz that vibrates at a precise frequency. It keeps time in watches and microcontrollers.
Diode
Lets current flow one way only, in the direction the triangle points. The bar marks the cathode.
LED
Light-emitting diode. Arrows pointing out mean light leaves the part. It needs a series resistor to limit current.
Zener diode
Conducts backwards at a set voltage, so it is used to hold a voltage steady. Look for the bent ends on the bar.
Photodiode
A diode that passes more current when light hits it. Arrows pointing in mean light falls on it, the reverse of an LED.
NPN transistor
The emitter arrow points out: "Not Pointing iN". A small base current switches a much larger collector current.
PNP transistor
The emitter arrow points in: "Points iN Proudly". It turns on when the base is pulled below the emitter.
Op-amp
Operational amplifier. It amplifies the difference between its + (non-inverting) and − (inverting) inputs.
Cell
A single cell. The long plate is positive and the short plate negative. An AA cell gives about 1.5 V.
Battery
Several cells joined in series. Strictly, a battery means more than one cell.
DC voltage source
An ideal source that holds a fixed voltage and polarity, whatever current is drawn.
AC voltage source
A voltage that keeps reversing direction. Mains is 230 V at 50 Hz in India and Europe, 120 V at 60 Hz in North America.
Ground (earth)
The 0 V reference that every other voltage in the circuit is measured from.
Switch (SPST)
Single pole, single throw: one circuit, either on or off. It is drawn open here.
Push button
Normally open: the circuit closes only while the button is held down, then springs back.
Lamp
A lamp or indicator light. Some drawings show the filament as a small loop inside the circle instead of a cross.
Motor
Turns electrical energy into rotation.
Loudspeaker
Turns an electrical signal into sound by moving a cone back and forth.
Antenna
Sends or receives radio waves.
Ammeter
Measures current in amperes. It goes in series with the part being measured.
Voltmeter
Measures voltage. It connects in parallel, across the part being measured.
AND gate
Output is 1 only when every input is 1.
OR gate
Output is 1 when at least one input is 1. Note the curved back and pointed nose.
NOT gate
Also called an inverter. The output is the opposite of the input, and the small circle marks the inversion.
NAND gate
An AND followed by a NOT. Any logic circuit can be built from NAND gates alone.
NOR gate
An OR followed by a NOT. Output is 1 only when every input is 0.
XOR gate
Exclusive OR: output is 1 when the inputs differ. The extra curved line behind the body sets it apart from OR.
Wire junction
The dot means these wires are joined.
Wires crossing (not joined)
The hop shows the wires pass each other without connecting. Many modern drawings use a plain cross with no dot instead.