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Design & Technology

Components

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Standard symbols guide

The standard symbols for the key components used in electronic circuits are shown in the table below.

Electronic circuit symbols

The cell symbol looks like a letter T with a bigger, upside-down letter T on top.The symbol for an LED looks like a diode with two arrows pointing away from it.Push-to-make switch circuit symbolThe diode symbol is triangular, pointint towards the cathode. A vertical bar is on the triangle's point next to the cathode.The bell symbol looks like a letter D.Voltage rails circuit symbol
CellLight-emitting diode (LED)Push-to-make switchDiodeBellVoltage rails
The battery symbol is made from several cells connected in series.The flashing LED symbol looks like a diode with an opposite-facing triangle inside, and arrows leading away.Push-to-break switch circuit symbolThe thyristor symbol is a downwards-pointing triangle with a horizontal bar on its point, and another line coming in from the leftThe symbol for a microphone looks like a circle touching a vertical line.The Earth symbol is three horizontal lines tapering to a downwards point
BatteryFlashing LEDPush-to-break switchThyristorMicrophoneEarth
The symbol for a resistor is a vertical rectangle on a vertical line.The bi-colour LED symbol looks like a rectangle with two opposite-facing diodes inside, with arrows pointing away from the box.The symbol for a switch is a line moving away from the vertical, showing the switch in an open position.The symbol for a transistor looks like a sideways table. The Collector is on the top, the Emitter on the bottom. The Base is on the left.The buzzer symbol looks like a backwards letter D.A box with eight numbered pins leading out.
ResistorBi-colour LEDSingle-pole single-throw switchNPN transistorBuzzer555 timer IC
The symbol for a variable resistor looks like a resistor, with a diagonal arrow over it.The symbol for a tri-colour LED looks like two LED symbols facing each other, with a line coming out from where they joinA switch has two positions, with a line extending to the currently connected top path.A FET is shown by three wires from the right terminating near a perpendicular line which leads off to the left.The loudspeaker symbol looks like an inverted cone.Operational Amplifier circuit symbol
Variable resistorTri-colour LEDSingle-pole double-throw switchField effect transistor (FET)Loud-speakerOperational amplifier (op-amp)
The sybol for a potentiometer looks like a resistor with an arrow pointing at it on the side.The symbol for a photo transistor looks like an NPN transistor with arrow pointing towards it.The capacitor symbol looks like two letter Ts facing each other.The AND gate has two inputs and one output. The symbol looks like a letter D.The lamp symbol looks like a circle with an X going through it.The voltage regulator symbol is a rectangle with lines coming out from three of its sides.
Potent-iometerPhoto transistorCapacitorAND gateLampVoltage regulator
The symbol for a thermistor looks like a resistor, with a diagonal line over it, ending with a short vertical section.The symbol for an opto-isolator looks like an LED next to a photo transistor.The symbol for a polarised capacitor looks like a normal capacitor, but with polarity symbols.The OR gate has two inputs and one output. The symbol looks like a letter D where the left line of the D is bent inThe symbol for a motor is the letter M inside a circle.Two wires crossing look like a plus sign.
ThermistorOpto-isolatorElectrolytic capacitorOR gateMotorCrossing of conductors
The symbol for an LDR looks like two arrows pointing at a rectangle.The Ammeter symbol is an A in a circle.The symbol for a piezo crystal oscillator looks like two letter Ts facing each other with a square between them.A NOT gate has a single input and one output. The symbol is a triangle with a circle on the point leading to the outputThe symbol for a voltmeter is the letter V inside a circle.Wires joining can look either like two lines touching, or a circle showing where the join is.
Light-dependent resistor (LDR)AmmeterPiezo crystal oscillatorNOT gateVoltmeterJoined conductors

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