Download 555 Timer

Technology
Electronics and Control
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Electronics and Control
The 555 timer is an 8-Pin D.I.L. Integrated Circuit or ‘chip’
Notch
Pin 1
What it looks like
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Electronics and Control
Operation:
•Contains 25 transistors, 2 diodes and 16 resistors
• Maximum operating voltage 16V
• Maximum output current 200mA
• Best treated as a single component with required
input and output
INPUT
PROCESS
OUTPUT
If you input certain signals they will be processed / controlled
in a certain manner and will produce a known output.
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Electronics and Control
What the 555 timer is used for:
•To switch on or off an output after a certain time delay i.e.
Games timer, Porch light, Childs mobile, Exercise timer.
•To continually switch on and off an output i.e.
Hazard warning lights, Soft toy, Bicycle indicators.
•As a pulse generator i.e.
To provide a series of clock pulses for a counter.
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Electronics and Control
Digital Terminology:
To use the 555 timer correctly you have to be aware of
the correct terminology:
• Monostable
Time
• Astable Time
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Electronics and Control
• MONOSTABLE:
This is a system which has only one stable state.
It can be made to change but it will always return
to its original stable state. A spring operated
push button switch is an example of this.
Monostable circuits are used as timers and as a
single pulse generator.
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Electronics and Control
Monostable Circuit
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Electronics and Control
Component list:
Monostable PCB circuit layout:
R1= 33k(Or/Or/Or)
R2= 1k (Br/Bl/Re)
R3= 470(Ye/Vi/Br)
R4= 470(Ye/Vi/Br)
2 No. LEDs
SW1= Toggle Switch
SW2= Tactile Switch
555 IC
3No.Terminal Blocks
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Electronics and Control
• ASTABLE:
This is a system which has no stable state. It
changes from one state to the other all the time.
A pendulum swings from one side to the other
continuously. Astable circuits are used to flash
lights or sound a loudspeaker. It can act as a
square wave oscillator
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Electronics and Control
Astable Circuit
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Electronics and Control
Component list:
Astable PCB circuit layout:
R1 = 470(Ye/Vi/Br)
R2= 1k (Br/Bl/Re)
R3= 470(Ye/Vi/Br)
VR1= 100K
SW1= Toggle Switch
C1=10uF Capacitor
2 No. LEDs
555 IC
With VR1 set at 68K
flash rate = 1 per sec
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Electronics and Control
Components
Astable Project Board
R1=100 ohms
R2=100 ohms
R3=100 ohms
R4=2200 ohms
R5=1K ohms
VR1=100k
C1=10uF
Q1=BC 337-16
D1=1N4148
SW1=Toggle
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Electronics and Control
Warning signal: 4 LEDS flash simultaneously
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Electronics and Control
Buzzer and 4 LEDs Oscillate ON/OFF – Lorry Reversing
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Electronics and Control
Theme : A Safe Environment
Monostable:
Egg Timer : Food / Electrical safety
Bath / Oven Timer
Astable:
Hazard / warning lights / school crossing
Bicycle indicators
Burglar Alarm
Steep Gradiant Indicator
Personal Alarm
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