1. 1 Electronics and Control Technology

2. 2 Electronics and Control The 555 timer is an 8-Pin D.I.L. Integrated Circuit or ‘chip’ What it looks like Notch Pin 1

3. 3 Electronics and Control Operation: Contains 25 transistors, 2 diodes and 16 resistors Maximum operating voltage 16V Maximum output current 200mA If you input certain signals they will be processed / controlled in a certain manner and will produce a known output. INPUT PROCESS OUTPUT Best treated as a single component with required input and output

4. 4 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.

5. 5 Electronics and Control Digital Terminology: To use the 555 timer correctly you have to be aware of the correct terminology: Monostable Time Astable Time

6. 6 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.

7. 7 Monostable Circuit Electronics and Control

8. 8 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 Monostable PCB circuit layout: Component list:

9. 9 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

10. 10 Astable Circuit Electronics and Control

11. 11 Electronics and Control 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 Component list: Astable PCB circuit layout:

12. 12 Electronics and Control 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 Components Astable Project Board

13. 13 Electronics and Control Warning signal: 4 LEDS flash simultaneously

14. 14 Electronics and Control Buzzer and 4 LEDs Oscillate ON/OFF – Lorry Reversing

15. 15 Electronics and Control Theme : A Safe Environment Astable: Hazard / warning lights / school crossing Bicycle indicators Burglar Alarm Steep Gradiant Indicator Personal Alarm Monostable: Egg Timer : Food / Electrical safety Bath / Oven Timer