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Any explanation for this flashing LED schematic? + one small question

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Triple-H

New Member
Hi everyone!

I am new to electronics, and I read most of 'ELECTRONICS FOR DUMMIES' book.
So I found a schematic for a flashing LED using an LM555 IC and a potentionmeter to control the flashing speed [I attached the schematic with values of components]

I did the project on a breadboard and it is working perfectly fine :D

HOWEVER, I still DON'T have an idea about what exactly happens in this circuit.
I know what each component does, but I can't understand how arranging them this way makes the thing work :confused: :confused:

So here are my questions:
- Why did the author put capacitors of different types in the circuit? and why did he arrange the resistors this way? and how did he know that he should use these specific values?

In the title, I said I had another question, so here it is ;) :
- Are beginners supposed to learn by assembling circuits without knowing how they EXACTLY work? + Do you recommend any method of learning electronics??

Thank you for help :)
 

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Mr RB

Well-Known Member
Hi. :) It's a bit difficult trying to understand circuits as a beginner. You should download a copy of the 555 timer datasheet, the astable circuit you posted will be covered very thoroughly in the datasheet. If the datasheet is a little hard to understand you might want to do some reading on basic electronics, ie what resistors do, what capacitors do etc.

By assembling the circuit and making it work you've already come a long way towards understanding it, that's a good way to learn too. I'm sure lots of people blew up some 555 timers when they first started.

And speaking of that you might want to put a 1k resistor in series with your 1meg pot. So you don't blow up your 555... (the datasheet will explain). :)
 

tom_pay

Member
Hi

This circuit is called a Multivibrator. It goes from 5v to 0v at specific rate. They are a great little device. The 555 timer has specific outputs, to use it as a multivibrator it needs these components to be where they are, for it to work. As well it needs them to be of a specific value to 'clock' at a specific rate. To calculate these go to 555 Calculator and try it out.

I learned electronics by talking to a ex-uni teacher as well as the God Google. He's great fun. If either of these can tell me I ask the world through this forum!!

Hope it helps!
 

Triple-H

New Member
Hi. :) It's a bit difficult trying to understand circuits as a beginner. You should download a copy of the 555 timer datasheet, the astable circuit you posted will be covered very thoroughly in the datasheet. If the datasheet is a little hard to understand you might want to do some reading on basic electronics, ie what resistors do, what capacitors do etc.

By assembling the circuit and making it work you've already come a long way towards understanding it, that's a good way to learn too. I'm sure lots of people blew up some 555 timers when they first started.

And speaking of that you might want to put a 1k resistor in series with your 1meg pot. So you don't blow up your 555... (the datasheet will explain). :)
I downloaded the datasheet, and to be honest, I understood NOTHING :D
and I did some reading on basic electronics. But still, I understood NOTHING :D

I guess I will keep making circuits until I suddenly figure out how this circuit actually works :)

Thanks for help!
 

Triple-H

New Member
Hi

This circuit is called a Multivibrator. It goes from 5v to 0v at specific rate. They are a great little device. The 555 timer has specific outputs, to use it as a multivibrator it needs these components to be where they are, for it to work. As well it needs them to be of a specific value to 'clock' at a specific rate. To calculate these go to 555 Calculator and try it out.

I learned electronics by talking to a ex-uni teacher as well as the God Google. He's great fun. If either of these can tell me I ask the world through this forum!!

Hope it helps!
Thanks for link! I will give it a try...
and thanks for your advice ;)
 

Triple-H

New Member
Try this site, it may help you visualise what is happening;
555 Square Wave Generator
THANK YOU SO MUCH!!!!

This is almost exactly what I was looking for! I noticed it is an applet that allows you to do all sorts of experiments and test voltages and current at different locations! This applet is just too awesome ! :eek:

Thank you all for your useful links and advices :)
 
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