Square wave detector

[James Arthur]

Thanks in tones ..for all the idea.
The signal is not 50% duty cycle. This signal is coming from other
card. I need to glow a LED if square wave is present. Voltage level is
digital i.e 0V and +5V. Basically if there is toggle in the line I
need to drive low and if no toggling drive high.
If this detection can be done using simply digital circuit along with
capacitor and Diode will be great.

Thanks in advance
Regards
Pinku

(view in Courier font)
R1 C1

-/\/\--||-----+----.

| |
--- --- LED
D1 \ / / \ ~~>
--- ---
| |
=== ===
GND GND

James Arthur

 

[Jerry Avins]

Thanks in tones ..for all the idea.
The signal is not 50% duty cycle. This signal is coming from other
card. I need to glow a LED if square wave is present. Voltage level is
digital i.e 0V and +5V. Basically if there is toggle in the line I
need to drive low and if no toggling drive high.
If this detection can be done using simply digital circuit along with
capacitor and Diode will be great.

Lets repeat some of those questions:

Is the not-so-very-square wave the only possible signal present?

How soon after the signal is applied must the response occur?
How soon after the signal is removed must the response occur?
Couch these times with reference to a period of the waveform.

Is the 5V really 5, or could it be 4.5 sometimes? Could 0V in be .8"

Jerry

 

[Paul Hovnanian P.E.]

Close. The local multiversity, UCSC, has a "History of Consciousness"
major, which should provide an endless supply of graduates capeable of
detecting a square wave:
<http://humwww.ucsc.edu/HistCon/>
<http://en.wikipedia.org/wiki/History_of_Consciousness>

I hate to admit it, but there was a time in the early 1960's when I
worked on a job that resembled a "square wave detector". In this
case, I was sentenced to stare at a Tek 520A vector display, for what
seemed like endless hours, and yell of help if anything changed.
Unfortunately, things did change so I really did need to pay
attention. After about 10 consecutive days of this nonsense, I
simulated a mental breakdown, and was assigned a more creative task.
That was sweeping the floor from all the crud that was falling from
the ceiling during construction.

B.F. Skinner trained pigeons to peck at a CRT to run a guided missile.
<http://en.wikipedia.org/wiki/Project_Pigeon>
<http://www.spring.org.uk/2007/06/pigeon-guided-missiles-superstitious.php>
I guess a graduate student can be trained to do the same.

I doubt it would work. There's no way of telling whether or not their
political sympathies mit change in mid-course.