Window comparator using single 555 ?

Externet

Well-Known Member

• Dec 14, 2008

• #1

Hi.

If I understand well, a 555 chip is a window comparator by itself, the window being 1/3 to 2/3 Vcc.

Can the window be tailored to yield output between 2.9 and 3.1 Volts ? [the Vcc supply is +5V]

 

blueroomelectronics

Well-Known Member

• Dec 14, 2008

• #2

Why not just use a dual comparator?

 

K

kchriste

New Member

Forum Supporter

• Dec 14, 2008

• #3

Externet said:

Can the window be tailored to yield output between 2.9 and 3.1 Volts ? [the Vcc supply is +5V]

Click to expand...

No, because you can only get at one of the junctions of the resistive divider via pin5. Therefore, the upper window voltage will always be double that of the lower one.
EDIT: I guess you could do something like this with a 555, but it's not very elegant:

 

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Last edited: Dec 14, 2008

Externet

Well-Known Member

• Dec 14, 2008

• #4

Thanks, fellows.
The circuit works perfect with a LM393, but needed to duplicate and ran out of those chips . Tried LF353 on hand; does not work. Will have to wait until more come in.
Miguel