exam questions Flashcards
If an LED has a 2v drop in a 4.5v circuit. How much voltage?
2.5v
why are IC sockets useful
- stops component from being damaged by soldering.
- the IC is easily removable to swap or change if in the wrong orientation.
- easier to replace a faulty chip
what is bistable
a latching device with 2 stable states (high or low, on or off)
in a decade counter where is the enable pin connected
connected low
Uses of CAD
- testing the idea to see if the components are connected correctly and have the right values.
- Designing the circuit in circuit wizard.
- Lets a person visualise their design and or circuit idea that can be sent direct to a printer, cnc or cad.
what does a potentiometer do?
adjust voltage and resistance to set light/heat level for sensors.
3 legs of an FET
gate, drain, source
3 legs of a transistor
base, collector, emmiter
3 legs of a thyristor
gate, anode, cathode
advantages of rapid prototyping
- complex 3 d shapes made, they can be amended if needed.
- made from a 3d drawing
- complex components are produced quickly.
How does vacuum forming work
Material clamped into place Heat applied Former raised into material Vacuum pump switched on Pump off / table lowered Formed shape removed
voltage for a microconrtoller
5v
voltage regulator purpose
to stabilise the voltage for a circuit so it doesn’t damage any components
purpose of a darlington pair
to go from a low current device to a high current output like a speaker from a microcontroller.
uses for standards in manufacture
- upholds reputation so sell more.
2. to make sure there is no fault which will need to be compensated.
advantages of pick and place component machines
much faster than humans
need for less employees so save money
what a thyristor
a latching component which stays on even once currents stop being applied.
why is a diode used?
protect from back emf
protect components
what is a pull down resistor
connects input low, so prevents accidental triggering
what is switch bounce?
Several pulses produced from each press of the switch
how to stop switch bounce
using a debouncer circuit/ monostable to create a clean signal
advantages of injection moulding for high production
low skilled workers needed
mould can be re used
low cost for each component
3 things that improve a vacuum forming mould
rounded corners, vent holes and filleted joints
monostable works by
pin 2 connecting low, circuit triggered.
pin 3 high then low until pin 6 is measuring how full capcitor
pin 7 discharges
output turn on for this time delay
astable
same as mono but pin 2 is triggered by discharge of pin 6
capacitor polarised sides are shown by
long and short lead
minus sign
how can voltage drop be measured
by a multi meter
how to use a multi meter
select v range
attach a lead to anode and cathode
connect probes either side of the componet
take a reading
prototypes are
working models made in development stages
resistors
used for pulling high and low and to protect componets from too much current
benifits of packaging a darlington pair in 1 component
fewer components so reliable
smaller circuit board
function of an astable
to create a flashing output bby being a pulse generator
digital signal
2 states on or off
anologue signal
varying signal
advantages of a microcontroller
wide range of features
programmable
adaptive inputs and outputs
one off product
specialised, complex
made for 1 client
only 1 made
expensive to produce
high volume production
tooling required to be set up once.
skilled workforce isnt needed
made in big quantities
advantages to seven segment display to an led
looks better
easier solder cos less legs
Single component so not many components
what is a one of product
a singular product complex ans specialised. requires a skilled workforce and time and money
high volume productions
many products are made. low skilled workforce
what is a prototype
working model consisting of the correct measurements used as a real world testing
