1. Key Stage 3-4
555 ic
Using a (555 IC) as a Monostable / Astable Circuit
555 IC
Live Wire / PCB Wizard - (555 IC) Circuit
RA Moffatt

2. 555 ic
555 IC
555 IC
(555 IC) Circuit

3. WALT Electronics We Are Learning To
Understand the concept of a 555IC, Integrated Circuit.
Use Live Wire / Crocodile Technology software to construct the electronic circuit diagram.
This is because ..
We can learn how to use digital electronic circuits which provides opportunities for a range of systems that control timing, flashing effects, etc. for different applications in project work.
Remember to:
refer to the Potential Divider principle
Black Box 555IC

4. Using the 555 IC Integrated Circuit as a
Monostable Timer:
You will have an opportunity to:-
Design/Model an electronic circuit (Monostable Timer)
using the 555 (IC) Integrated Circuit using Live Wire /
Crocodile Clips / Technology;
Listen to the AVI files (38) and (44) and explain how
each of these circuits work?
Manufacture & Test the PCB printed circuit board.
Circuit (38) will keep the Light ‘off’ for a set-time;
Circuit (42) will keep the light ‘on’ for a set-time.

5. Using the 555 IC Integrated Circuit in
Astable mode:
You will have an opportunity to:-
Design/Model an electronic (Astable) circuit (44)
using the 555 (IC) Integrated Circuit using Live Wire /
Crocodile Clips / Technology;
Model and test this circuit using a breadboard;
Manufacture & Test the PCB printed circuit board.
Circuit (44) will switch the Light / LED ‘on’ and ‘off’
intermittently.

6. 555 Pin Connections 0 Volts Trigger Output Reset +ve (4.5 – 16V)2 3 4 8 7 6 5
Output
Reset
+ve (4.5 – 16V)
Supply Voltage
Discharge
Threshold
Control Voltage

7. 555 IC Circuit Monostable ‘Off for a Time’1 4 8 2 6 7 5 3
Circuit (38) 112 Working Circuits

8. Using a 555 IC as a Monostable:
555 timer is configured as a Monostable circuit.
This means when the IC is triggered, the output (pin 3) will go high (9V) for a pre-determined time i.e. the LED is unlit. Output pin 3 will then return low, (0V), and remain in this condition until re-triggered.
How circuit is triggered:
Consider PTM switch is open, the voltage at bottom of R2 is 9V (connection also to pin 2).
When PTM switch is closed the voltage on pin 2 will drop to 0V, and if immediately released the voltage will again jump to 9V i.e. a negative pulse has been produced. This negative pulse applied to pin 2, triggers the IC, and the output (pin 3) goes high for a period that can be set by theVR1, C1 combination

9. 555 IC Circuit Monostable ‘Off for a Time’1 4 8 2 6 7 5 3
Circuit (38) 112 Working Circuits

10. Calculating the Time Delay:
For the 555 timer IC the delay time is given by the equation –
t = 1.1 x C x R
R = 470 k Ohms C = 100 micro Farads
= Ohms = Farads
t = 1.1 x x
t = 51.7 seconds

11. 555 IC Circuit Monostable ‘Off for a Time’
Applications: Egg Timer / Chess Timer Press-ups Timer etc.

12. 555 IC Circuit Monostable Touch-Timer ‘On for a Time’1 4 8 2 6 7 5 3
Touch Contacts
Circuit (42) 112 Working Circuits

13. 555 IC Circuit Monostable Touch-Timer ‘On for a Time’1 4 8 2 6 7 5 3
Touch Contacts
Circuit (42) 112 Working Circuits

14. 555 IC Circuit Monostable Touch-Timer ‘On for a Time’
Circuit (42) 112 Working Circuits

15. 555 IC Circuit: Astable
Circuit (44) 112 Working Circuits

16. 555 IC Circuit: Astable
Circuit (44) 112 Working Circuits

17. 555 IC Circuit: Astable

18. (R1 + 2 R2)C1 Frequency of the Astable Timer:
The frequency of the 555 timer IC can be calculated as shown:
f = 1.44
(R1 + 2 R2)C1
f = x 68000) x
1.37
f = 1.05 hz approximately one flash per second. R1
R1K R2 C1
10 uF
68K Ohm

19. 555 IC Circuit: Astable
Circuit (44) 112 Working Circuits

20. 555 IC Circuit: Astable Components: 555 IC
270 ohm resistor from +9v to the collector of the NPN transistor.
Two 1K resistors
One NPN transistor (try any alternative).
One 100K preset resistor.
One 47uf capacitor
Black and red wire.
One LED

21. 555 IC Circuit: Monostable – Game/s Timer
NPN
Transistor
NPN Transistor turns-off when the voltage at the base is greater than 0.6 Volts

22. 555 IC Circuit: Monostable – Game/s Timer
NPN Transistor turns-on when the voltage at the base is less than 0.6 Volts

23. 555 IC Circuit: Monostable – Astable (Display Stand)
SW 1 pressed motor ‘on’ for a time ‘off’ then ‘on’ ‘off’ etc.

24. 555 IC Circuit: Monostable – Astable (Display Stands)
Suggested GCSE Projects / Theme (Display Stands – Shop Windows)
Using Electronic / Mechanical Systems

25. 555 IC Circuit: Motor Speed Control Mark_Space
Circuit (87) 112 Working Circuits

26. 555 IC Circuit: Motor Speed Control Mark_Space

27. 555 IC

28. 555 Timer Projects

29. Suggested Key Stage 3 Project: Aroma Fan
Ideas for the box top
Butterfly / Ladybird
Top of box design cut with the laser however this shape could be simplified when cut by hand!
Motor ‘on’ for a set time, fan blows air through scented petals into the room

30. Typical Project applications for a 555 IC: -
Monostable:
Astable:
Aroma Fan
Shaky Hand Game
Bicycle Hazard Lights
Bicycle Indicators
Egg Timer, Telephone Timer, Game / Chess Timer etc.
Burglar Alarm
Electronic Dice
Sensitive Touch Switch
A Child’s mini electric organ
Simple Siren
Bleeper circuit
Random Number Generator etc, etc..

31. Monostable Circuit NOR gate Monostable 2 5 1b 6 3
Switch is pressed, potential at pin 2 is 5V (logic 1).
Assuming that pin 3 (output of IC 1b) is at 0V.
Output (pin 1) will switch from logic 1 to logic 0.
Voltage change is transmitted instantly by the capacitor, making pins 5 & 6 change to logic 0, causing the output pin 4 to change state from logic 0 to logic 1 and the LED to switch on.

32. Monostable Circuit
NOR Gate

33. Monostable Circuit
NOR Gate

34. http://www.uoguelph.ca/~antoon/gadgets/555/555.html Dark Detector:
It will sound an alarm if it gets too dark. For example, this circuit could be used to notify when a lamp (or bulb) burns out. The detector used is a regular cadmium-sulphide Light Dependent Resistor or LDR, for short, to sense the absence of light and to operate a small speaker. The LDR enables the alarm when light falls below a certain level

35. Tilt Switch:
Actually really a alarm circuit, it shows how to use a 555 timer and a small glass-encapsulated mercury switch to indicate 'tilt'. The switch is mounted in its normal 'open' position, which allows the timer output to stay low, as established by C1 on start-up. When S1 is disturbed, causing its contacts to be bridged by the mercury blob, the 555 latch is set to a high output level where it will stay even if the switch is returned to its starting position. The high output can be used to enable an alarm of the visual or the audible type. Switch S2 will silent the alarm and reset the latch. C1 is a ceramic 0.1uF (=100 nano-Farad) capacitor

36. Metronome:
A Metronome is a device used in the music industry. It indicates the rhythm by a 'toc-toc' sound which speed can be adjusted with the 250K potentiometer. Very handy if you learning to play music and need to keep the correct rhythm up

37. Ten-Minute Timer:
Can be used as a time-out warning for Ham Radio. The Federal Communications Commission (FCC) requires the ham radio operator to identify his station by giving his call-sign at least every 10 minutes. This can be a problem, especially during lengthy conversations when it is difficult to keep track of time. The 555 is used as a one-shot so that a visual warning indicator becomes active after 10-minutes. To begin the cycle, the reset switch is pressed which causes the 'Green' led to light up. After 10 minutes, set by the 500K potentiometer R1, the 'Red' led will light to warn the operator that he must identify

42. A view inside the 555 IC / Black Box

43. Useful Electronic Web-Sites:
Acknowledgement:
Thanks to Maurice Lynch (WELB) for use of his excellent and invaluable
112, Circuits resource in this presentation.
Raymond Moffatt.