As a loving dentist I hope that all children use this in a
positive way and so making their teeth as white as snow.
Brainstorm
I have decided to put my toothbrush holder onto a bathroom 555
cupboard. I will use a push to make switch so when the
toothbrush is taken out the timer will start and a push to Light emitting diode
break switch so when the toothbrush is put back in the
circuit will break and the timer will stop. I can either have
the toothbrush holder:
have a clock on it’s lips, Nicad
have a metronome timer or Battery
have a chattering teeth timer. Light
Mains Energy source
Vacuum formed plastic
Design
Clock on lips
Wood Metronome
Box Toothbrush holder
Timer
buzzer
Sound Chattering teeth
Speaker
Task Analysis:
To make the timer for my toothbrush holder I will need to look at
how to make timers. The components I will be using are shown in the brainstorm. I want to look at:
What do they do?
What are they made of?
How big are they?
Do they have any common features?
Three things that I will look at when I do this are:
Input Process Output
E.g. timer e.g. a relay e.g. sound
Specification:
- The product should cost under £8 to build for each unit. 1000 units will be made.
- The product must be waterproof.
- The product must weigh less than 3kg. The smaller and lighter, the less the cost.
- The timer will need to be accurate within 3 minutes.
- The time-up warning will need to be in the form of a loud buzzer. The warning should go on for 30 seconds.
- The electronics will need to be hidden inside a robust casing.
- The power source must last up to 30 hours.
- The casing and logo should be shown appealing to children so they want to use it. Bright colours should be used.
- The power supply should be renewable.
- It should be 100mm deep.
- It should be user friendly; users should be able to understand how to use it easily.
- The case should be safe to use. There must be no sharp edges or anything that may harm the children.
Research:
To build the circuit I will need to use the right components 555 timer:
with the right amount of components used in each case. It is good to make a delay. You can do it with
To do this I will research……… transistors. The 555 is an IC which is specially
Made for the job. You trigger it, start the
Action, and it gives a high output for a time.
Light Emitting Diodes: This voltage is a pulse. A pulse is a steady
A light emitting diode is a semiconductor device that gives out light voltage that lasts for a fixed time. I can adjust
when a small current flows through it. LEDs are used extensively as the pulse length of the 555 outputs, by
electronic indicators. They are available in a range of sizes and shapes, connecting different components. Below is an
and give out light of a variety of colours. The most common types are example of a 555-pulse generator. To trigger
cylindrical and glow red, green, or yellow. This will be what I use. They circuit, connect pin 2 to the ground. Output is
are used in displays on devices such as bedside radios and car from pin 3. You can measure the length of the
instruments. It is usually made from gallium arsenide phosphide, which pulse you have to look at the LED.
emits light when a suitable current flows through it. The light output
is caused by a release of energy that occurs as electrons pass from
one side of the semiconductor junction to the other. The current
flowing through an LED must be limited to avoid damaging the device.
As it is a diode it will only let current pass through it in one direction.
Motors:
Electric Motors and Generators, group of devices used to convert mechanical energy
into electrical energy, or electrical energy into mechanical energy, by electromagnetic
means. A machine that converts mechanical energy into electrical energy is called a
generator, and a machine that converts electrical energy into mechanical energy is
called a motor.
Battery:
Battery, device that converts energy stored in chemicals into
energy in the form of electricity. It consists of two or more
electric cells connected in series or parallel. A number of new
types of batteries have been designed for use in electric vehicles.
Improved versions of conventional storage batteries have been
developed for electric cars, but they still suffer the drawbacks of
either short range, high expense, bulkiness, or environmental
problems. Advanced batteries that show promise for use in electric
vehicles include lithium-iron sulphide, zinc-chlorine, nickel metal
hydride, and sodium-sulphur. Such batteries are also being developed
by electricity supply companies to be used for “load levelling”, to
compensate for momentary system load fluctuations. Such battery
modules could be installed close to sites of variable demand. They
cause few environmental problems and occupy little
space.
Vacuum Forming:
Most electronic products have plastic casings. These can be made by
Vacuum forming high-density polystyrene sheet. The advantages of
Vacuum forming are:
a rigid shape that requires no fabrication.
a repeatable shape
a variety of details can be added on.
complicated rounded shapes can be achieved by adding details.
By using vacuum forming, I can easily shape my containers. The only
problem with this is that stretching of plastic sheet can thin corners,
meaning it is less safe.
Nicads
A modern NiCad cell is made with both plates being made of steel. The two plates are seperated
By a thin layer of porous plastic. This separator is soaked in potassium hydroxide solution. All
NiCads are fitted with a seal, which acts as a safety valve to release gas generated in the cell.
The amount of cadmium used is very small so the cell is not as unfriendly to the environment as
We believe. This is why I want to use them. NiCads thrive on heavy use. This is also good for me
because the toothbrush holder will be used often. They would be able to last longer than batteries.
