# Schematic Help and some advice

Discussion in 'Homework Help' started by 90alx, Nov 13, 2014.

1. ### 90alx Thread Starter New Member

Nov 13, 2014
4
0
Hi guys,

I saw this video on youtube:

and I said "I want to learn to make things like that", so I started to learn electronics.But I know that I have to learn more than electronics, but I don't know what else.Mechatronics ?Mechanics ?Embedded systems ?Can somebody give me an advice what else should I learn to make gadgets like the one from video ?

Now...I attached the schematic.I don't want you guys call me a lazy because I am asking your help.
I need someone to explain and if he can to draw me on a paper how does the current flow in every wire?What is it's value on every wire ?What is the voltage on every component ?What voltage is on each of the 2 capacitors and transistors ?Which components are in series and which are on parallel ?

I know a little about the series and parallel connections, but only on the simple schematics.Maybe I can't figure it, because of those capacitors and there connections with the tranzistors..

I am asking all this things because, this schematic(from what I understood), make that LED's to don't light both on the same time, only one each at a time.

I tried to simulate with Orcad, but I saw that on the transistor's base the voltage was 1 and a few, but the transistor's open voltage is 0.6V...

So I am asking you again, please, can you explain me all this things ? Maybe if I will see the flow of the current and voltage drawed on a paper, I will understand better.

Thank you very much!

File size:
2.1 MB
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42
2. ### MrChips Moderator

Oct 2, 2009
12,446
3,362
Geez, we cannot teach you everything you need to know about electronics in one thread. But we can try to teach you how to fish, so to speak.

Start out by doing some experimenting and discovering on your own. Get an LED, a bunch of resistors from 100Ω to 1kΩ, a 9V battery and a DMM.
Wire the LED, current limiting resistor and 9V battery in series. Measure the voltage across the LED and the resistor.

Set the DMM to read current and put the meter in series to measure current in the circuit.

Do the calculations using Ohm's Law and verify your results.

3. ### WBahn Moderator

Mar 31, 2012
17,757
4,800
What he said.

You need to learn this stuff starting with the basics and moving up steadily to more and more advanced stuff. Start with simple projects and kits and progress from there. Frankly, even if we did the full analysis and described it all to you, you would only grasp a small fraction of it because you simply have not poured the foundation that will let you grasp the bulk of it. That's not a put down in any way -- we all were there and we are all still there and we will all remain there for the rest of our lives. It's just that we have taken the time, blood, sweat, and tears to build a foundation that let's us grasp a hell of a lot more than we used to be able to, but there will always be plenty that is still beyond our reach, at least until we expand that foundation some more.

4. ### 90alx Thread Starter New Member

Nov 13, 2014
4
0
Thank you for your replies.I bought a breadboard, with a few components, a 555 timer, but I made the stupidity to not buy the most important thing: the DMM.I will buy it.Right in this evening I will order it.
But until than, please, can you tell me, at least, why the LED's are flashing each at a time and not both in the same time ?

Thank you.

5. ### ISB123 Well-Known Member

May 21, 2014
1,239
527
It's a flip flop,its supposed to do so.

6. ### WBahn Moderator

Mar 31, 2012
17,757
4,800
The explanation is given to the left of the schematic. Basically, in order for one transistor to be on, the other transistor must be off. But this is not a stable condition and so the transistor that is on is discharging the capacitor that is keeping the other one off and, at some point, the other one turns on which rapidly shuts the first one off. But now it is discharging the capacitor that is now holding the other one off.

7. ### 90alx Thread Starter New Member

Nov 13, 2014
4
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But there are not in parallel ?So they shouldn't charge and discharge in the same time ?

8. ### WBahn Moderator

Mar 31, 2012
17,757
4,800
You are correct... they are NOT in parallel. So there is no reason that they either should or shouldn't charge at the same time.

If you are thinking that they ARE in parallel, then you need to take a step back and consider what it means for two components to be in parallel.

To understand the basic working of this circuit, you need to understand the basic workings of resistors, capacitors, first order circuits, energy continuity constraints, and transistors operating as switches. None of this needs to be known in any great depth, but you need to understand the basics. So work through a text or tutorials or something similar to start building that foundation.

9. ### JoeJester AAC Fanatic!

Apr 26, 2005
3,373
1,159
Do you know the time constant of the circuit as shown? That is a multivibrator circuit. Did you build it?

There are other experiments that the instructions talk about.

When you did the transition analysis in orcad, what time did you select for the ending?

10. ### 90alx Thread Starter New Member

Nov 13, 2014
4
0
@JoeJester I didn't select the time.I am new in Orcad.
Thank you for replies guys, I am going to review what Wbahn said.