# The 555 timer

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Published on June 7, 2019

Author: AbdulrazakZakieh

Source: slideshare.net

1. Integrated Circuits (ICs) The 555 Timer abdalrazak.zk@gmail.com 1By: Abdulrazak Zakieh

2. It was invented by Hans Camenzind in “1971” abdalrazak.zk@gmail.com 2

3. About of “The 555 Timer” is sold every year abdalrazak.zk@gmail.com 3

4. It can be used for many functions , most commonly for precision timing ranging from microseconds to hours, and Insha’ Allah you will know how to do it. Now let’s investigate its pins.abdalrazak.zk@gmail.com 4

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6. the clocking mark We start numbering from the upper left pin closest to the clocking mark abdalrazak.zk@gmail.com 6 The pins on an IC are numbered counter-clockwise starting with the upper left pin closest to the clocking mark

7. abdalrazak.zk@gmail.com 7 Q:Where is the clocking mark for these Ics?

8. You should first look at the……….. Now, where is the first pin??? abdalrazak.zk@gmail.com 8

9. Now we can talk about The 555 Timer pins and learn briefly the function of them abdalrazak.zk@gmail.com 9 I think these pins are obvious Control Voltage You can override the internal trigger circuit Threshold When the voltage reaches a certain level the timing cycle ends This is the output Reset Applying a low voltage to this pin will reset the timing function and the output becomes low Discharge pin You connect a capacitor to pin 7 Triggering pin If you apply a low voltage on this pin you’ll trigger the internal circuit

10. Astable (Oscillator) Monostable Bistabel (Flip-Flop) abdalrazak.zk@gmail.com 10 AND THAT’S DEPENDING ON THE WAY THAT YOU CONNECT IT

11. abdalrazak.zk@gmail.com 11 Generally, if you want to know the function o an IC, its specification, and how to connect it correctly you should look at its “Datasheet”

12. abdalrazak.zk@gmail.com 12 In the Astable mode, the 555 timer produces a continuous stream of rectangular pulses having a specified frequency. If you want to have an Astable mode you should connect “The 555 Timer” as shown in the next figure

13. abdalrazak.zk@gmail.com 13 What is the meaning of “Astable” ?

14. abdalrazak.zk@gmail.com 14

15. abdalrazak.zk@gmail.com 15 f= 1.44 (