Still need help with Schematics

Discussion in 'Homework Help' started by Kid347, Sep 9, 2016.

Aug 14, 2015
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I am still in need of help reading and understanding Schematics. I have attached a new schematic of a circuit that I am trying to assemble, Here is a list of my questions

1. I see that pins 2 & 6 connect, but after that I see that C1 and R2 how does this connection finish?
2. R1 connects to pin 7 but at the other end does it connect to pin 8 or to 6v?
3. does the dot on the connection from pin 7 R1 to the other end pin 8 or 6v, does the dot on top of pin 8 mean that it goes to 6v? if it was underneath the dot on pin 8 would it mean that it connects to pin 8?
4. C2 goes from ground, but does it connect to pin 8? then it goes to R3 to a LED to Pin 3. does the positive side of the LED connect to pin 3?
5. What exactly does R2 do? I know that one side connects to pin 7 , but where does the other end connect?
I really wish that they had pictures that go along with the schematic, but I have been trying to learn this for over a year now and I still don't understand how it works. Thank you in advance.

• 555 dummy alarm.jpg
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Jul 18, 2013
15,885
4,657
Here is the connection explanation.
The lower one is the more common now.

Also look at the manuf sheet on the 555 some will show the internal diagram of the IC.
Max.

3. crutschow Expert

Mar 14, 2008
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5,537
All your questions can be readily answered when you understand that a line indicates a wire connection and a dot on the wire indicates a connection between the wires
Thus, for example, all these points are wired together (order makes no difference):
Pin 8 -- Pin 4 -- C4 -- R1 -- C2 -- R3 -- 6v to 12v
also
Pint 2 -- Pin 6 -- R2 -- C1

Aug 14, 2015
70
0
I know how the connections work, when they are connected and when they don't, but for instance I see that pin 2 connects to pin 6, but from there does it connect to C1 or R2 or both and how would you make the connections? I can figure out that R1 connects to pin 7 but what about the other connection is it pin 8 or 6v 12v? and lastly C2 I can figure out that one end connects to ground but does the other connection go to pin 8 or to R3? I pretty much know what all the symbols are and what a single connection means. but when a component connects to multiple components I just get lost.

5. SLK001 Senior Member

Nov 29, 2011
1,165
422
The straight across connected diagram shown in post #2 is very much deprecated today. The reason for this is that third or beyond generations (copies) of the original could fade the junction "dot" out (or even fade one in) leaving a lot of ambiguity in the schematic.

The proper connection of nets is shown below. As you can see, there is no ambiguity with this method:

6. crutschow Expert

Mar 14, 2008
19,789
5,537
All the connections with the dots are connected together.
To wire the circuit you just run wires between all the connections indicated (order is not important).
I think what you are missing is that you can run more than one (or several) physical wire to the same point.
One wire on the schematic may require several physical daisy-chained connections to make the required continuity.

Thus, for example, you run a wire from pin 2 to pin 6,
another wire from pin 2 (or pin 6) to the plus end of C1,
another wire from the plus end of C1 to one end of R2.

Then you run a wire from pin 7 to the other end of R2,
another wire from that end of R2 to one end of R1.

Etc.

Does that make more sense?

7. crutschow Expert

Mar 14, 2008
19,789
5,537
Why did you copy my post with no comment?

Aug 14, 2015
70
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Yes it is starting to make more sense. I also found some good info in the education section of All about circuits. I will give it a try tomorrow. Thank You very much for the help. it is greatly appreciated.