3WALT 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 principleBlack Box 555IC
4Using 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 howeach 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.
5Using 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.
7555 IC Circuit Monostable ‘Off for a Time’ 14826753Circuit (38) 112 Working Circuits
8Using 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
9555 IC Circuit Monostable ‘Off for a Time’ 14826753Circuit (38) 112 Working Circuits
10Calculating the Time Delay: For the 555 timer IC the delay time is given by the equation –t = 1.1 x C x RR = 470 k Ohms C = 100 micro Farads= Ohms = Faradst = 1.1 x xt = 51.7 seconds
11555 IC Circuit Monostable ‘Off for a Time’ Applications: Egg Timer / Chess Timer Press-ups Timer etc.
12555 IC Circuit Monostable Touch-Timer ‘On for a Time’ 14826753Touch ContactsCircuit (42) 112 Working Circuits
13555 IC Circuit Monostable Touch-Timer ‘On for a Time’ 14826753Touch ContactsCircuit (42) 112 Working Circuits
14555 IC Circuit Monostable Touch-Timer ‘On for a Time’ Circuit (42) 112 Working Circuits
15555 IC Circuit: AstableCircuit (44) 112 Working Circuits
16555 IC Circuit: AstableCircuit (44) 112 Working Circuits
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)C1f = x 68000) x1.37f = 1.05 hz approximately one flash per second.R1R1KR2C110 uF68K Ohm
19555 IC Circuit: AstableCircuit (44) 112 Working Circuits
20555 IC Circuit: Astable Components: 555 IC 270 ohm resistor from +9v to the collector of the NPN transistor.Two 1K resistorsOne NPN transistor (try any alternative).One 100K preset resistor.One 47uf capacitorBlack and red wire.One LED
21555 IC Circuit: Monostable – Game/s Timer NPNTransistorNPN Transistor turns-off when the voltage at the base is greater than 0.6 Volts
22555 IC Circuit: Monostable – Game/s Timer NPN Transistor turns-on when the voltage at the base is less than 0.6 Volts
23555 IC Circuit: Monostable – Astable (Display Stand) SW 1 pressed motor ‘on’ for a time ‘off’ then ‘on’ ‘off’ etc.
29Suggested Key Stage 3 Project: Aroma Fan Ideas for the box topButterfly / LadybirdTop 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
30Typical Project applications for a 555 IC: - Monostable:Astable:Aroma FanShaky Hand GameBicycle Hazard LightsBicycle IndicatorsEgg Timer, Telephone Timer, Game / Chess Timer etc.Burglar AlarmElectronic DiceSensitive Touch SwitchA Child’s mini electric organSimple SirenBleeper circuitRandom Number Generator etc, etc..
31Monostable 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.
34http://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
35Tilt 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
36Metronome: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
37Ten-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