Re: Output voltage monitor circuit ideas

"Rappinglove" <your.mum@xxxxxxxxxxxx> wrote in message
news:1151330901.169699.91510@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Hello Group,
I am looking to designing an output monitor circuit for a power supply
with up to 10 outputs. These outputs could be from 2V to 48V
The input supply for the circuit must not be above 28V 2A
The output will be LEDS lighting to show that the output has dropped
out.
Must have a quick response time, if the output drops out for a few ms I
need to know about it.

I was thinking a comparator type circuit comparing output with 0V and
then an LED switching on to alert the user that the output had dropped
out. Any other ideas or circuits?

Thank you
Dan


Dan,
I don't think you want to compare the output voltages to 0V. What if the output
voltage just sags below a specified voltage; not necessarily going all the way
to 0V... wouldn't you want to know about that as well? What constitutes a
drop-out? The voltage falling all the way to 0V, or below a specified
threshold?
A bank of LM339 quad comparators would probably do your job. Three chips, and
you even have a couple comparators left over.
Make a reference voltage source of about 1V, and scale the power supply outputs
to 1V. Connect the reference to one comparator input, the scaled outputs to the
other. Send the comparators' outputs into 555 one-shots if you want a momentary
flash when the voltage drops. If you want the LED to latch on when the
comparator trips, send the outputs into a D-latch. Of course, the LEDs connect
to the 555 flasher or to the latch output.
That should do it.

--
Dave M
MasonDG44 at comcast dot net (Just substitute the appropriate characters in the
address)

Some days you're the dog, some days the hydrant.


.

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