Flashcards
Engineering: Electronic systems 1
Cards in this deck (64)
- 1What is voltage and what is it m measured in?This refers to the energy of the electrical supply.
(This pushes current around an electrical component)
It is measured in V. - 2What is current and what is it measured in?This refers to the flow of charge within a circuit. It is measured in amperes(A)
- 3What is resistance and what is it measured in?This refers to the ability of electricity to flow through a circuit.
It depends on the material.
It is measured in Ohms - 4What is the formule for these 3 properties of electricity?
- 5What is an anode?The positive leg on the LED.
- 6What is the cathode?The negative leg on the LED.
- 7What is the circuit symbol for an LED?
- 8What do the two arrows on an LEDs circuit symbol represent?The LED has the potential of giving out light.
- 9What does the polarity of the LED refer to?The polarity of the LED refers to which way round the the LED must be connected. If it is connected the wrong way around, the LED will not light up.
- 10Electronics units.
- 11Prefixes.
- 12Worked example of how to calculate which resistor to use.
- 13Worked example of how to calculate which resistor to use.
- 14What is a fixed resistor?
- 15How can we calculate tolerance?
- 16Breadboard past paper questions
- 17Breadboard past paper questions
- 18What is an electronic input?An electronic input is something that is used to activate or trigger an electronic system.
Examples include switches. - 19What is a PTM switch?Push to make switch
- 20What is a PTB switch?A push to break switch
• It is used to momentarily stop a current from passing - 21What is a SPST switch?A single pole single throw switch
• The pole refers to the pivot
• The throw refers to the track connection
• It is commonly used to latch a circuit on or off
• It is used to symbolize rocker switches, toggle switches, on-off switches, slide switches - 22What is a SPDT switch?A single pole double throw switch.
• The pole refers to the pivot
• The throw refers to the track connection
• It is commonly used to latch 2 separate circuits so that while one is on, the other is off, and vice versa.
• It is used to symbolize rocker switches, toggle switches, on-off switches, slide switches - 23What is a DPST switch?The pole refers to the pivot
• The throw refers to the track connection
• It is commonly used to latch 2 separate circuits on or off at the same time
• It is used to symbolize rocker switches, toggle switches, on-off switches, slide switches - 24What is a DPDT switch?• DPDT – double pole, double throw
• The pole refers to the pivot
• The throw refers to the track connection
• It is commonly used to latch 4 separate circuits on or off
• It is used to symbolize rocker switches, toggle switches, on-off switches, slide switches - 25What does a pull down resistor do?It ensures that Vout returns to 0v.
Eliminates floating voltages
(Eg. static) - 26What does a pull up resistor do?Pull up resistor ensures Vout is normally on.
- 27Potential Divider
- 28Examples of calculations on Vout.
- 29Flowchart on making a LED light up for 3s when the PTM is activated.
- 30A graphical representation of both an analogue signal and a digital signal.
- 31State 3 examples of an analogue signal.Volume on a radio
A dimmer light
LDR - 32State 3 examples of a digital signal.Light switch can only be on or off
PTM
Power button - 33What is a monostable?It is a time delay circuit.
- 34How can a monostable be made, method 1?By using a 555 timer (integrated circuit) to construct a dedicated monostable circuit.
- 35What are the advantages and disadvantages of using an integrated circuit?Advantage is that it is cheap.
Disadvantages is that they are not 100% accurate and also can not be adjusted/re-programmed. - 36How can a monostable be made, method 2?By using a microcontroller based circuit.
- 37What are the advantages and disadvantages of using a microcontroller?Advantages
- Can be re-programmed
- Highly accurate
- Flexible- capable of a variety of different functions
Disadvantages
- PIC is more expensive than a 555 timer
- High set up costs (need computers and software)
- Need experts to programme PIC - 38How do you calculate time constant for a 555 timer monostable?
- 39Example of calculating time constant.
- 40A graphic representation of the output pulse of an astable.
- 41What is the time period for a microcontroller?Time high + Time low
- 42What does the frequency of an s astable tell us?The frequency of an astable tells us how many times a second the output goes on or off.
Frequency= 1 ÷ period - 43What is the method of turning an analogue signal into a digital signal?Method 1 - Use a component called a operational amplifier.
We will connect the operational amplifier to a particular type of circuit called a comparator. - 44A operational amplifier.
- 45What is a relay?The relay is used to link a low powered circuit to a high powered circuit.
• Relays are electrically operated switches.
- 46Mark/space ratio
- 47Describe what happens to the LEDs when the cirucit is swithced on and then triggeredi) Circuit switched on:
When the cirucit is switched on the red LED will become on and the green LED is off as the charge travels straight through and not into the 555 timer.
ii) Circuit triggered:
When the circuit is triggered the 555 timer gets triggered and the green LED comes on whilst the red LED is off.
- 48What is a darlington pair?It is when two transistors are used.
- 49What is a mosfet?
- 50Define the two types of electrical current• AC is alternating current, an electrical current that changes direction periodically
• DC is direct current, an electrical current that flows in one direction only - 51Why is AC used for mains electricity?• Mains electricity is an AC supply in the UK
• AC is relatively straightforward to transport over long distances. - 52What is the frequency of mains AC?• The AC frequency in the UK is 50 Hz.
• This means that it changes direction and back again 50 times per second.
• It is commonly used to power electric motors, e.g. in washing machines, tumble dryers, dishwashers - 53When and why is DC used?• Most electronic products / systems run using DC, e.g. mobile phones.
• DC is provided by batteries or cells.
• Sometimes a converter (mains adapter) is needed to turn AC into DC.
• This convert consists of a transformer to reduce the voltage, and a rectifier to turn AC into DC.
• Another example of a converter is the charger unit for mobile phones
• DC’s main advantage is it is reliable, efficient, and low power (safety). - 54List the types of batteries• Alkaline
• Zinc carbon
• Rechargeable - 55Describe the function of a switch• Switches are used to either ‘make’ or ‘break’ a circuit, therefore either allowing or stopping current flow.
- 56What two electrical output devices can be used to provide movement?• A motor and a solenoid.
• A motor converts an electrical signal (current - electrical energy) into rotary motion (kinetic energy plus heat energy plus light energy).
• Motors can be powered by AC or DC.
• There are several types of motor – DC solar motor, DC motor, servo motor, stepper motor
• A solenoid converts an electrical signal into linear motion.
• Solenoids are often used in automated locking and clamping systems. - 57What electrical outputs can be used to provide sound?• Buzzers
• Bells
• Loudspeakers - 58How do buzzers create sound?• A buzzer uses an internal oscillator to produce sounds when current flows through them.
• The single frequency of the sound produced by the buzzer depends on the design of the buzzer.
• They are commonly used in doorbells. - 59How do bells create sound?• A bell uses an electromagnet.
• When current flows through it produces a continuous clanging sound, e.g. a school bell.
• Bells are less common nowadays as they have been replaced with fully electronic sound output devices, such as loudspeakers or sirens - 60How do loudspeakers create sound?• Whereas buzzers and bells only require electrical current, loudspeakers require an oscillating electrical signal.
• The oscillating signal causes a card cone to vibrate, creating noise.
• A variety of sounds can be produced, depending on the frequencies of the electrical signals used. - 61Compare 2 electrical output devices can be used to create light?• Filament lamp – this consists of a thin coil of wire. When current passes through the coil it heats up, producing light.
• These usually demand a medium to a high current, and will therefore use up battery power quite quickly
• LED – light emitting diode
• Consists of an anode (positive) and cathode (negative)
• A protective resistor is needed
• Current demand is very low (about 20mA) - 62Define what is meant by a sensor input.A sensor input is a component that detects changes in the environment around it, for example light, or temperature
• The component turns this information into an electronic signal.
• It can be either digital or analogue. - 63What is an LDR?• An LDR is a light dependent resistor.
• Its resistance (ohms, ) depends on the level of light (lumens, lux) that surrounds it.
• Its resistance decreases as brightness increases, and vice versa.
• It provides an analogue signal. - 64What is a thermistor?• A thermistor is a heat dependent resistor.
• Its resistance (ohms) depends on the temperature (oC) of its surroundings.
• Its resistance decreases as temperature increases, and vice versa.
• It provides an analogue signal.
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- Flashcards on Engineering , created by AsimAli Rehman on 16/11/2018.
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