BE Lesson 8: Using the 555 IC timer chip. What is a 555 integrated circuit (IC) timer? Make a...
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Transcript of BE Lesson 8: Using the 555 IC timer chip. What is a 555 integrated circuit (IC) timer? Make a...
BE Lesson 8: Using the 555 IC timer chip .
• What is a 555 integrated circuit (IC) timer?• Make a blinking LED circuit using a 555 timer.• Make a railroad signal light using a second LED.• Vary the oscillation period.• Make an English police siren. • Make an electronic canary.
© 2012 C. Rightmyer, Licensed under The MIT OSI License, 20 July 2012
The 555 timer IC (integrated circuit)
physical appearance
schematic symbol
555
tim
er IC
12
345
67
8 GND
Trigger
Output
ResetControl voltage
Threshold
Discharge
Vcc
BE ckt 8-1. Using IC 555 to blink an LED
+
vo
lts
220
LED6.8K
16K
+10 F
on on on
off off offoff
Pin 3 voltage observedusing an oscilloscope
R1
R2R3
C1
555
12
345
67
8
[http://www.kpsec.freeuk.com/555timer.htm]
BE ckt 8-2. Adding a second LED to ckt 8-1
+
vo
lts
220
LED16.8K
16K
+10 F
R1
R2R3
C1
555
12
345
67
8
LED2
220
R4
BE ckt 8-3. Change the flashing cycle for ckt 8-2
+
vo
lts
6.8K
1K
+10 F
R1
R2
C1
R3
100K pot
555
12
345
67
8
220
LED1
R3
LED2
220
R4
Hookup diagram for ckt 8-3
1 2 3 4
5678
LED1
+10 FC1
6.8K
555+
9.0
volts
220
220
LED2
R4
1K
100 k pot
BE ckt 8-4. An English police siren
+
vo
lts
220
1K
120K
+0.01 F
R1
R2
R3
C1
470K R4
3904B
C
E
R5 10
NO
555
12
345
67
8
BE ckt 8-5. A chirping canary?
6.8K
33K
+
0.01 F
R5
R6
C2
.1 FR7
1K
R3
33K
NO
555
12
345
67
8
C3
3904B
C
E
3906B
C
E
+
F
R4
C1
47
R2
R13.3K
100K pot
+
volts