Generating an oscillator circuit using 555timer.....

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sword_fighter

New Member

• Mar 24, 2012

• #1

I need to generate a square wave pulse using 555timer...which has a maximum output voltage 5volt & minimum output voltage 1.4volts...and on time 60sec & off time 90sec...

I used astable circuit for making this particular pulse....but the minimum value is always coming to 0v instead of 1.4volts.....so i thought to use biased series clipper to make the minimum value 1.4volts....but i dnt have any value of that load resistor....so guess help me...how can i generate this square pulse using 555timer

 

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MrAl

Well-Known Member

Most Helpful Member

• Mar 24, 2012

• #2

Hi,

How accurate do these two voltages have to be?

 

audioguru

Well-Known Member

Most Helpful Member

• Mar 24, 2012

• #3

The datasheet for the 555 shows that its output swings from about +0.01V to about 1.35V less than its power supply voltage with no load.
Since you want the output low to be +1.4V (why?) then connect two series silicon diodes between its negative power terminal and ground.

 

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colin55

Well-Known Member

• Mar 24, 2012

• #4

Add two diodes to pin 1 of the 555.

 

Roff

Well-Known Member

• Mar 24, 2012

• #5

sword_fighter said:

I need to generate a square wave pulse using 555timer...which has a maximum output voltage 5volt & minimum output voltage 1.4volts...and on time 60sec & off time 90sec...

I used astable circuit for making this particular pulse....but the minimum value is always coming to 0v instead of 1.4volts.....so i thought to use biased series clipper to make the minimum value 1.4volts....but i dnt have any value of that load resistor....so guess help me...how can i generate this square pulse using 555timer

Click to expand...

Are you sure you need 1.4V? What is the application?

 

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sword_fighter

New Member

• Mar 25, 2012

• #6

I need ths as voltage regulator...for my microcontroller circuit....i need ths voltage tense to be accurate....

 

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sword_fighter

New Member

• Mar 25, 2012

• #7

pin 1 is used as ground....so can you just explain function of this diodes....???

 

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sword_fighter

New Member

• Mar 25, 2012

• #8

yah....MrAl.....the voltage must be accurate or tense to accurate....because I am using it as voltage regulator for my microcontroller circuit...

 

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sword_fighter

New Member

• Mar 25, 2012

• #9

colin please explain diode's function??

 

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colin55

Well-Known Member

• Mar 25, 2012

• #10

The diode give the output an offset.

 

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sword_fighter

New Member

• Mar 25, 2012

• #11

Okey Colin....but what kind of diode i should use? & what will there values?? is it work,as you know that pin 1 is always directly used to ground for 555 timer...

 

Last edited: Mar 25, 2012

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colin55

Well-Known Member

• Mar 25, 2012

• #12

Obviously two diodes with 0.7v drop each.
I think this whole exercise is way over your head.

 

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sword_fighter

New Member

• Mar 25, 2012

• #13

Okey now I understand...good idea....i will try it in my circuit....thanks dude...

 

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colin55

Well-Known Member

• Mar 25, 2012

• #14

[mod_edit: off topic]

 

Last edited by a moderator: Mar 25, 2012

Roff

Well-Known Member

• Mar 25, 2012

• #15

[mod_edit: off topic]

 

Last edited by a moderator: Mar 25, 2012

audioguru

Well-Known Member

Most Helpful Member

• Mar 25, 2012

• #16

[mod_edit: off topic]

 

Last edited by a moderator: Mar 25, 2012

Roff

Well-Known Member

• Mar 26, 2012

• #17

sword_fighter said:

yah....MrAl.....the voltage must be accurate or tense to accurate....because I am using it as voltage regulator for my microcontroller circuit...

Click to expand...

This doesn't make sense. You don't power a microcontroller with an oscillator.