Better 555 Duty Cycle Control (PWM).

Much better Duty cycle control using the 555 timer in an A-Stable mode of operation.

Many of you commented on my previous 555 video asking how to create a circuit that allows a “Duty Cycle” of 50% or less. i.e. making the On time equal to, or less than, the Off time.

If you have not seen my previous video, I suggest you take a look at that first by clicking the following link:-
   • How a 555 Works as a Timer.  

UPDATE:- I have now posted a new video explaining Capacitor Charge and Discharge timings, which can be found here:-
   • Capacitor Charge & Discharge Times  

Anyhow, in this follow-up video I show how, by simply adding a couple of diodes you have much greater control over the duty cycle. I also demonstrate how to adapt the circuit to make it a variable duty cycle or controllable PWM (Pulse Width Modulation) circuit.

The 555 calculation spreadsheet I put together for this video can be downloaded from here:-
🔗https://1drv.ms/f/c/10f323cd9840b5df/...

🔗NOTE:- The Amazon links provided below are affiliate links. They won’t cost you anything extra, but as an Amazon Associate, I earn a small commission from qualifying purchases. This helps support and maintain the channel—thank you for your support!

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 Potentiometers see one of my previous videos here:-
🔗   • How Potentiometers Work  

⏱️Timeline
-------------------
00:00:00 – Introduction
00:00:25 – Recap Previous 555 Video
00:01:28 – Charge & Discharge Timings
00:02:40 – Problem with Standard A-stable circuit.
00:03:10 – 555 Calculator (On/Off/Frequency & Duty Cycle)
00:04:40 – The solution.
00:05:55 – New Calculations
00:06:53 – Breadboard Layout of Circuit 1
00:07:59 – Oscilloscope Output of Circuit 1
00:10:03 – Circuit 1 Summary
00:10:53 – Variable Duty Cycle 1st Option
00:11:15 – Variable Duty Cycle Using Potentiometer
00:11:55 – Breadboard Layout Circuit 2
00:12:39 – Oscilloscope Output of Circuit 2
00:13:32 – Wrap Up

Correction:
10:05 the t1 & t2 results should both be 0.01525, not 0.0165 Seconds.