In this video I explain the building blocks of a 555 chip and how it interacts with the components you connect around it to become a “Timer”!
I talk through each stage of the 555 including
- Voltage Divider (comprising of three 5K resistors)
- Two Comparators
- The Flip-Flop
- NPN and PNP Transistors utilised for Discharge and Reset
We explore the Charge and Discharge times as the capacitor oscillates between the 1/3rd and 2/3rd voltage levels and verify that with an oscilloscope.
UPDATE:- I have now posted a new video explaining Capacitor Charge and Discharge timings, which can be found here:-
https://youtu.be/mllC-hiBepY?si=GKLhJfNhzj1pZE-2
For a follow up Video sharing viewer's Voting Poll on the 555, see my "The 555 Verdict" video here:-
https://youtu.be/S5gZ6LstiDs
Another follow up video showing how to gain better control over the duty cycle (percentage of the On time for each cycle) simply by adding a couple of diodes. Click here:-
https://youtu.be/4NXjBRarmeg?si=fJN0JaX3pYRRXPdR
If you are interested in the handy configurable Resistor boards I utilised you can purchase them from Amazon here:-
🔗https://amzn.to/3RYiX75
For more information about Voltage Dividers, see one of my previous videos here:-
https://youtu.be/FkfUatec0XY
⏱️ Timeline
--------------------
00:00:00 – Introduction
00:00:59 – PKAE Electronics Intro Theme
00:01:09 – Internal Stages starting with Voltage Divider
00:02:29 – Two Comparators
00:04:16 – Control Voltage Pin
00:04:32 – Flip-Flop & Output Driver Stage
00:05:40 – SR Flip-Flop Explained
00:07:27 – NPN Discharge Transistor
00:07:50 – PNP Transistor for External Reset
00:08:14 – Summary of Stages
00:08:39 – Comparator/Flip-Flip Experimenting (Theory)
00:15:54 – Comparator/Flip-Flip Experimenting (Bench Testing)
00:17:58 – Astable Circuitry – External Capacitor and Two Resistors
00:21:20 – Bench Testing Astable Mode
00:22:48 – Datasheet Astable Circuit Diagram
00:23:27 – Control Voltage Capacitor (Stability)
00:23:53 – Timing Calculations (On and Off Times)
00:25:41 – Bench Testing Timings with Oscilloscope
00:29:06 – Timing Summing Up
00:29:17 – Frequency Calculation
00:30:12 – Wrap Up.
🎶Intro Music from #inaudio :- https://inaudio.org/
Track = OddVision-HYPER POP