Transcript 555 Timer
Technology Electronics and Control 1 Electronics and Control The 555 timer is an 8-Pin D.I.L. Integrated Circuit or ‘chip’ Notch Pin 1 What it looks like 2 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. 3 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. 4 Electronics and Control Digital Terminology: To use the 555 timer correctly you have to be aware of the correct terminology: • Monostable Time • Astable Time 5 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. 6 Electronics and Control Monostable Circuit 7 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 8 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 9 Electronics and Control Astable Circuit 10 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 11 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 12 Electronics and Control Warning signal: 4 LEDS flash simultaneously 13 Electronics and Control Buzzer and 4 LEDs Oscillate ON/OFF – Lorry Reversing 14 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 15