Window comparator design

[Dave]

I think I need a window comparator circuit - I need to monitor a
voltage (8.4Vdc)and to give an indication (Vgood) but I also need to
give a >=8.5V(Vhigh) and <=8.3 (Vlow) indicators - could anybody help
with the design, I know I need to use op-amps or such-like but
analogue design definately isn't my area.

Cheers

Dave.

 

[kmaryan@gmail.com]

John's answer is certainly a good one and you should take it under
consideration, but depending on the level of sophistication needed you
might want to consider a digital solution using an A-D with a good
reference. Using comparators will definitely be cheaper, but if you
already have a microcontroller in your circuit, adding an A-D and then
making the comparison in software may be a bit more flexible. I've seen
this used for self-monitoring in some safety critical controllers I
work with.

Chris

 

[Rich Grise]

On Thu, 24 Feb 2005 08:38:56 -0800, Dave wrote:

I think I need a window comparator circuit - I need to monitor a
voltage (8.4Vdc)and to give an indication (Vgood) but I also need to
give a >=8.5V(Vhigh) and <=8.3 (Vlow) indicators - could anybody help
with the design, I know I need to use op-amps or such-like but
analogue design definately isn't my area.

+10v.
|
\
/ 1K5
\
| 8.5V dual comparator
+----------------|-\_______
\ +----|+/
/ 200R |
\ |
| 8.3V +----|-\_______
+---------- | ---|+/
\ |
/ 8K3 |
\ |
| |
GND |
|
Input ----------+

You could also try
http://www.google.com/search?q=%22window%20comparator%22

Have Fun!
Rich

 

[John Fields]

On 24 Feb 2005 08:38:56 -0800, blaildyors@quassouwko.mailexpire.com
(Dave) wrote:

I think I need a window comparator circuit - I need to monitor a
voltage (8.4Vdc)and to give an indication (Vgood) but I also need to
give a >=8.5V(Vhigh) and <=8.3 (Vlow) indicators - could anybody help
with the design, I know I need to use op-amps or such-like but
analogue design definately isn't my area.

---
Voltage comparators, not opamps.
Here's the basic idea:

news:07gs11pk4c83m2ffkg48dn3argk93t8aap@4ax.com

You need to post what the supply voltage is so that we can figure out
what the reference divider and the hysteresis resistors look like.

--
John Fields