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What do I need to make a 555 to output a 1 sec pulse?

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Can you please tell me what itmes I would need and how to lay it out so I can make a 555 timer have a 1 sec out pulse?
 

One suggestion is that if you need more precise control of the one second you are better off using a counter circuit with a higher frequency oscillator and some control logic.

One second region time constants operate at very high impedance levels which are affected by IC bias currents and PC board surface contaminations that draw leakage currents.
 

You might consider a divider circuit anyway, it might be cheaper than a large capacitor and the attendant high impedence headaches.

Some species of 555 timer have a built in divider chain, but then they aren't going to be as plentiful as the more generic 555 and therefore disproportionally more expensive
 

With 555 you're never get same period for impulse=1 and impulse=0. So my suggestion is to make oscilator with 555 and with some cmos divider make 1 sec.


Mr.Cube
 

I need a one sec pulse to input to a 4017 decade counter. What I need to to know what parts and a diagram of how to hook it up to get the one sec pulse.
 

Here you can find everything you need:

**broken link removed**
 

HI

Here is the right schematic to get accurate 1Hz pluse see attachment made in proteus
 

hi

i have reuploaded a better design with advance simulation
 

Thanks! What do I open the file with? I see a .jpg (which I can open) but then I see a data souce name file and a sec file.
 

FODRacing.com said:
Thanks! What do I open the file with? I see a .jpg (which I can open) but then I see a data souce name file and a sec file.
Click to expand...


hxxp//www.labcenter.co.uk and get a demo version to see how it works
 

Pls reference this 555 aplication,it have pulse out circuit and calculate method for 1 sec pulse.
 

alphi said:
Pls reference this 555 aplication,it have pulse out circuit and calculate method for 1 sec pulse.
Click to expand...

if the accuracy is the matter then 555 circuit can not give this and you must have to switch design based on crystal controlled oscillator
 

Get the datasheet of the 555 . You will find a chart with values for caps an resistors against the frequency of the 555 in mode ASTABLE
 

I dont think all 555 chips are the same and further more there is no guarantee all caps,resistors ever ever going to be exact for a precision of 1Hz.

Try max038 or try to use PIC micrcontrollers which I find more exact to such precision when is needed.
 

Oh forgot it. First make sure you know exactly the XTAL or Ceramic oscillator frequency. In case when oscillator is built in, measure it.

I think using PIC you can achieve 1Hz precisely.
 

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