555 timer numbers?

Thread Starter

Lightfire

Joined Oct 5, 2010
690
Hello,

I am confusing about 555 (NE555). In schematic dagram it have numbers but I am thinking if it is have also in real life.

So, please look at my attachment (the big circled red). The timer has 1,2,3,4,5,6 numbers.

Thanks
help?
thanks
 

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mbohuntr

Joined Apr 6, 2009
446
I figured Bill is probably at work so here is a 555 pic. The notch indicates the top, and the pins are numbered 1 - 8 starting at the top left, going down the left side, crossing the bottom and ending at the top right at pin 8 (counter-clockwise. )
 

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Thread Starter

Lightfire

Joined Oct 5, 2010
690
I figured Bill is probably at work so here is a 555 pic. The notch indicates the top, and the pins are numbered 1 - 8 starting at the top left, going down the left side, crossing the bottom and ending at the top right at pin 8 (counter-clockwise. )
But as you may see there, there's only 6 numbers.:(Help? pls. :D

Catapult
 

beenthere

Joined Apr 20, 2004
15,819
Not all schematics are really good. Go to the link and get a data sheet for a 555 timer - http://www.datasheetcatalog.com/datasheets_pdf/L/M/5/5/LM555CN.shtml

You will see the schematic does not have the .01 uF cap on pin 5 (may not be needed in this circuit). Pin 7 is used in timing the output pulse, as is pin 6. The 555's are not supposed to be in astable configuration, so all they do is switch from on to off.

What do you expect this circuit to do?
 

Thread Starter

Lightfire

Joined Oct 5, 2010
690
  • resistors: 470 ×4, 1k ×2, 10k ×8
  • capacitors: 0.1µF ×4, 1µF radial
  • diodes: 1N4148 ×4
  • LEDs: 1 each red, green, yellow and blue, all 5mm diameter
  • 555 timer ICs (such as NE555) ×4
  • DIL sockets for ICs: 8-pin ×4
  • bleeper suitable for 9V
  • on/off switch
  • push switch ×5
  • battery clip for 9V PP3
  • 2-core cable such as 'figure 8', about 8 metres
  • stripboard: 10 rows × 50 holes
As you may the bold line. Isn't it the one which will make the timer have 8 pins??? :(
 

DerStrom8

Joined Feb 20, 2011
2,390
But as you may see there, there's only 6 numbers.:(Help? pls. :D

Catapult
Hi, Catapult! :)

As mentioned earlier, in this schematic, only the used pins are labeled. You may find some that have them all labeled. It doesn't really matter--The only pins numbers you really need to know are the ones you use. Make sense?

As you may the bold line. Isn't it the one which will make the timer have 8 pins??? :(
The 555 timer already has 8 pins. The DIP (dual in-line package) is simply a socket for the chip. These can be helpful on permanent circuit boards, as it allows you to remove the chip (you don't have to solder the chip to the board--you only need to solder the socket).
Der Strom
 

mbohuntr

Joined Apr 6, 2009
446
Hey Catapult!

On the schematic, it says pins 5 and 7 aren't used. ( pretty small writing, easy to miss. )

@ everyone I'm not understanding how setting the "trigger line" high prevents other output led's from displaying, The 1n4148's prevent pin three from bias by the trigger line. Am I missing something here?
 

Wendy

Joined Mar 24, 2008
23,415
Got a special request via PM, so at the risk of repeating what every one has already said...

The basics.

This is a 8 pin chip top view...



Pin 1 is the upper top left corner. It will either have a notch in the side or a dimple in the plastic as shown. The numbers go down and in a circle, so pin 8 is the top right corner. I'm including my pinout sheet which is part of my PaintCAD package, which labels each pin by number.

If a pin number is not shown, it is not used. It really is that simple.

If you want to see how a schematic matches against a real schematic you can look at any of my 555 articles. The first link is free. :D

555 Schmitt Trigger


So, get anything in the mail yet?
 

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Thread Starter

Lightfire

Joined Oct 5, 2010
690
Um, just a couple of questions.

1) If there is no label there, so the numberings at the schamtic really doesn't matter or what?

2) Anyway, will the project will work then? :D
 

mbohuntr

Joined Apr 6, 2009
446
As Been there said... What do you think it will do? Can you explain how you think it works? Understanding how it is supposed to work is important to electronics. The numbers show you how to connect the components.
 

DerStrom8

Joined Feb 20, 2011
2,390
1) If there is no label there, so the numberings at the schamtic really doesn't matter or what?
The labels (numbers) are only for the pins that are used. If you see a "2" on the schematic, it means that that is pin 2 of the 555 timer. The numbers on the schematic are crucial--without them, you wouldn't know which pin is which, and where each one connects.
Der Strom
 

engrdm

Joined Feb 19, 2010
10
remember that schematic symbols are made in such a way that it is easy and neat to connect them . hence u will find alot of ICs that dont show the power and gnd pins. some reorder the pins to make the connections easy.. The chip in real life would be as is shown in datasheet. for 555 pin configuration check this link where the same issue is discussed
 
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