TekMason asked 7 years ago
Hi Rui and Sara,
Thanks for the great materials that you guys produce.
I am working my way through the Electronics for Beginners book and have a few questions/suggestions.
- Deep dive links.
It would be helpful to have some links in each relevant topic to deep dives into the subject matter.
A good example would be for Module 4 > Unit 1 – Introducing the 555 Timer. There are a lot of excellent Internet resources that have good explanations of how the 555 really operates like How a 555 Timer Works and The Best 555 Timer Tutorial. - In Module 4 > Unit 2 – Flashing an LED with the 555 Timer it would be nice if you were to calculate the frequency that the 555 will operate at
My calculation in Excel, f=1.44/((1000+2*470000)*0.000001) gives me 1.53hz or a cycle time of 0.65 seconds. -
Module 4 > Unit 3 – Controlling the LED Brightness with PWM is pretty lite on explaination:
- Can you explain what is the purpose of the 1N4001 diodes are?
-
How does one calculate the frequency when the diodes are introduced with various pot settings? - How does one calculate duty cycle at a given pot setting?
Speaking more generally about the Q&A Forums. It would be very useful to have the Q&A Forum broken down into categories. This will become more and more important as the number of forum posts grow.
Thx,
TekMason
Sara Santos Staff answered 7 years ago
Hi TekMason. Thank you for your interest in this topic and for sharing your thoughts.
- In relation to the deep dive links, you are right. We should definitely include more resources when it comes to the 555 timer. We’ll do that in a future update. Our intention with that mini ebook was to focus more on building the circuit and not so much on theoretical concepts.
- Yes, your calculations are right. We should also add those calculations to the book, so that the reader knows how to calculate duty cycle.
- The diodes are used so that we can have different charging and discharging times. And so, we are able to produce different duty cycles.
You need to imagine that when you set your potentiometer to a certain position you have different resistance values on each side. In the example on Unit 3, we’re using a 10kOhm pot. Imagine that in a certain position the pot has 2k on one side and 8k on the other. The charging of the capacitor (green line on the figure below) can only take place through the 8k part of the potentiometer because the diode on the right side. When the capacitor discharges (red line), it can only take place through the 2k part of the pot because of the diode on the left side. This will make possible having different charging and discharging times that you can change by rotating the pot.
You may also take a look at this example: https://circuitdigest.com/electronic-circuits/1-watt-led-dimmer
I hope this helps.
Thanks 🙂
Rui Santos Staff answered 7 years ago
Hi again.
To answer your question about the Q&A forum, I agree with you it should have those features. But the software that I currently use that integrate seamlessly with WordPress is pretty limited and it doesn’t offer those features.
Most of the members also prefer to ask questions on Facebook.
Regards,
Rui
aandraz answered 5 years ago
Hi Rui! I might find an error in the Unit 4 – Led in series. In is written that we need to get rid of 1V from 3LEDs, but if i am not mistaken it should be 3 x 2V = 6V -> 9V (VCC) – 6V = 3V, which we should compensate with resistor?
Please correct me if i am wrong. Thank you.
BR
Sara Santos Staff answered 5 years ago
Hi.
Yes. You are right.
The calculation should be: (9 – (3*2))/0.03
So, you can use a 100 Ohm resistor.
I’m sorry for the typo and thank you for letting us know.
We need to fix that in the next update.
Regards,
Sara