I work in the IS department in a small hospital. My background is 20 years as a Medical Technologist (blood, urine, etc) Now I'm in IS supporting Lab functions. The manager in the lab wants an "alarm" to sound when a label prints on a label printer. My wonderful background in electronics says, no problem. I simply need an optical/light sensor that when the path is broken it opens an alarm circuit until it is reset. Yep, no problem. Only, I have no idea how to do it. #-o I've talked to the bio-med tech (electronics guru) and he's looking at it but I told him I knew some pretty ingenious folks (that's you guys :wink:) that might have some ideas. It can be battery powered, like a 9 volt circuit with a nagging buzzer or something like that. Any takers?
Perhaps something like http://www.discovercircuits.com/PDF-FILES/optoint2.pdf with a buzzer attached?
I suspect you’re likely to find that the bigger problem isn’t the electronics, but the mechanics of how to mount the thing to make sure the label always passes through the beam.
I assume this is to act as a notification that a label is ready to be processed in some way? If so, you’ll need to think about how to handle a label ringing the buzzer when no-one hears it. Do you ring the buzzer every minute whilst there’s a label present, or does it just buzz once when the (first) label appears, or do you want it ro buzz once per label. You’ll probably need slightly different circuits in each case.
Good suggestions Chris.
A couple of other ideas:
Is there any light/LED on the printer that lights when it’s printing? If so it might be easier to mount a phototransistor to sense that than deal with sensing the label.
Is it a network printer, or does it have a regular parallel interface? If it’s parallel I could very easily come up with a beeping cable 
Ok, I knew I could count on you guys!
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There is no light that lights while printing. (There is however a sensor that reads the light between each label for “end of label” alignment) but I really don’t want to mess with that circuitry.
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The “alarm” would be a ring until they reset type, so if someone was not physically present, when they returned they would immediately know.
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It is a network printer running propietary medical software.
I haven’t checked out the PDF file yet, just stopped for lunch to see if there was any ideas.
Thanks!
Dave
Is it a dot matrix that vibrates? If so maybe something like one of those cheap portable intruder alarms would do it. The pdf is a good circuit for it if you decide to go the optical path ( :lol: )
Not a dot matrix, I’m going to pass the PDF on to the biometrics guy. Thanks again.
Agreed, the PDF is a good circuit 
It might be easier to mount a reflective sensor in place of the slotted type.
I took the schematic to the Biomed guy, he’s going to see what he can come up with. I’ll let you all know how we make out.