Key Stage 3-4 555 ic

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

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

3. Electronics WALT

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. +ve (4.5 – 16V) Supply Voltage 8 1 0 Volts Trigger Discharge 7 2 Output Threshold 6 3 Control Voltage Reset 5 4 555 Pin Connections

7. 8 4 7 6 2 5 1 555 IC Circuit Monostable ‘Off for a Time’ 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. 8 4 7 6 2 5 1 555 IC Circuit Monostable ‘Off for a Time’ 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 = 470 000 Ohms = 0.0001 Farads t = 1.1 x 470 000 x 0.0001 t = 51.7 seconds

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

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

13. 8 4 7 6 2 5 1 555 IC Circuit Monostable Touch-Timer ‘On for a Time’ 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 http://www.williamson-labs.com/480_555.htm

18. R1K R1 R2 C1 10 uF 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 = 1.44 f = 1000 + 2 x 68000) x 0.00001 f = 1.44 1.37 f = 1.05 hz approximately one flash per second. 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) Monostable Astable 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 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 • 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. 2 5 1b 6 3

32. NOR Gate Monostable Circuit

33. NOR Gate Monostable Circuit

34. 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 http://www.uoguelph.ca/~antoon/gadgets/555/555.html

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: http://www.interq.or.jp/japan/se-inoue/e_menu.htm http://users.pandora.be/educypedia/electronics/circuitsbysubject.htm http://www.uoguelph.ca/~antoon/gadgets/555/555.html http://home.maine.rr.com/randylinscott/learn.htm http://skyscraper.fortunecity.com/plug/587/index.html http://ourworld.compuserve.com/homepages/Bill_Bowden/homepage.htm http://555-timer.clarkson-uk.com/projects/ http://en.wikipedia.org/wiki/555_timer_IC Acknowledgement: Thanks to Maurice Lynch (WELB) for use of his excellent and invaluable 112, Circuits resource in this presentation. Raymond Moffatt.