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Topic: Supply voltage (Read 2 times) previous topic - next topic

Krupski


That circuit still has the buffer output connected to 5V


I know... but I figured that it's just a mistake in the drawing. Hopefully it's not ACTUALLY wired that way.
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Docedison

#11
Dec 15, 2012, 08:29 pm Last Edit: Dec 15, 2012, 08:33 pm by Docedison Reason: 1
@ *dhenry* a Schmidt trigger input inverting buffer is good engineering practice to 'clean up' the output of a photo-transistor.
The connection from the buffer output to Vcc isn't though.

Bob

{Edit}Data Sheet attached
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"The solution of every problem is another problem." -Johann Wolfgang von Goethe
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dhenry

Quote
he's using that HC14 to sharpen up the detector output.


Which isn't needed at all: look at the pin's internal diagram.

Docedison

@ *dhenry* you are expecting my feeble brain to anticipate you... Which Pin? I see an NPN transistor, a photo transistor with a 104 resistor from collector + 'HC14 input to Vcc.
I don't see any "Pin" that would counter indicate the use of a schmitted buffer, replace it or in any other way mitigate the requirement... Let the rest of us in on your little secret because
I still don't see where my original observation has changed in any way...

Quote
@ *dhenry* a Schmidt trigger input inverting buffer is good engineering practice to 'clean up' the output of a photo-transistor.
The connection from the buffer output to Vcc isn't though.



Bob
--> WA7EMS <--
"The solution of every problem is another problem." -Johann Wolfgang von Goethe
I do answer technical questions PM'd to me with whatever is in my clipboard

nhatnam06dt1



That circuit still has the buffer output connected to 5V


I know... but I figured that it's just a mistake in the drawing. Hopefully it's not ACTUALLY wired that way.


You're right. I draw the wrong. It must be like this:


Thank all comments!

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