Patient call system design

[SimonW]

Dear All,

I have been asked to design and build a simple patient call system.


Intended operation.
--------------------------
Switch X is pressed which turns on LED X and a buzzer beeps for 500ms


Circuit description
----------------------

When S X is pressed it supplies power to both LED X and monsotable (M) which triggers a buzzer (B)

There is only one monostable and buzzer for all 3


design questions
----------------------

Which monostable IC should I use if I want to keep the trigger permanantly triggered but rather
activate the monostable with the supply of power to the monostable?


ANY ALTERATIONS OR ALTERNATIVE DESIGNS WOULD BE VERY MUCH APPRECIATED

Thank You

 

[jpanhalt]

Which monostable IC should I use if I want to keep the trigger permanantly triggered but rather
activate the monostable with the supply of power to the monostable?


ANY ALTERATIONS OR ALTERNATIVE DESIGNS WOULD BE VERY MUCH APPRECIATED

Thank You

Why not use just a toggle switch? Forget the silicon version.

Not quite sure what this device is supposed to accomplish in its final embodiment.

John

 

[dr pepper]

Didnt quiet understand the question, is this a homework project.

The 555 is a classic choice for this circuit, theres probably a design on the net allready to do just this.

You can make the output time period finite by putting a 100nf in series with the trigger input of the 555, so that the buzzer wont stay on for longer than the time period if the button is held down.

 

[KMoffett]

So the pushbutton switch is the type that once pressed, stays closed, so the LED stays lit, but the buzzer is only buzzes briefly? Or are you thinking of somehow using a momentary pushbutton?

Ken

 

[SimonW]

Clarification...

The switches are the toggle variety latching , once on they will stay on..... once switched on I would like the appropriate LED to stay on and a brief buzzer output to signal to customers that there is an update to the display

SW1 doctor A .... LED outputs are to signal to the patients in the waiting room
etc..
etc..

I know that the LED will work

How can I trigger the monostable by simply applying and removing power to the monostable

 

[jpanhalt]

I don't understand the need for a buzzer. Also, if there are only 3 signals, it is probably a pretty small waiting area. Why not handle it in a more personalized manner? Most patients appreciate a personalized approach.

If this is really a model that you think can be scaled up, then consider some of the problems of scaling up such an LED/buzzer system in a waiting room with 25 to 100 patients. I am assuming of course that this project is for real or should emulate a real situation. That is, it is not just an assignment to light 3 LED's and give a short pulse when each is lit.

If it is the latter, you don't need to control the monostable power, just use the trigger/reset and don't allow retriggering.

If it is for a real situation, then there is a lot more to discuss. Start with how big is the room, how big a practice, how many patients per hour/day, how many examining rooms, is it for specimen collection, nurse exams, or physician exams? Do you have to deal with regulations like HIPAA in the USA? Is this a system for telling the doctor or other care provider that a patient is in the examining room, or is it to notify the patient the patient is is "his turn?"

John

 

[dr pepper]

Use a 555 connected as a monostable, connect pin 2 through a 100nf to ground and the same pin 2 through a 22k to +volts, when you apply power to the 555 it will do its time cycle with the output hi then return to low once timed out.

 

[KMoffett]

Can we assume that there are 3 switches, 3 LEDs, and but only one buzzer? A common arangement.

Ken

 

[Jaguarjoe]

If this is going in a hospital, there might be problems with enriched oxygen areas. O2 itself doesn't burn but it sure gets the ball rolling when other things arc or spark in its presence (like switches).
If there maybe lives depending on the operation of this thing, you might want to back out of this. The liability would be too great.
Skip flaky 555's and mono's, just use a very small microcontroller.

 

[KMoffett]

SimonW,

I think it's time to expand on the description the project. Is this a real installation?...is it in a hospital or clinic?...are electricians going to install all of the hardware/wiring? As joe stated, the hospital environment can be fraught with legal issues when it comes to custom equipment.

Ken

 

[SimonW]

Thanks for all the advice and opinions...... it is part of a real installation..... it is in a UK house converted into a doctors surgery...... therefore no legal issues or hazardous or critical enviroment.

 

[KMoffett]

What is the layout of the doctors suite? Do you envision the switch to be in each exam room, with the LED over the door and one buzzer in the waiting area? Or an LED over the door and a set of three numbered LEDs in the waiting room? Are LED's going to be bright enough to be useful?

Can yougive us a floor plan and how the patients are processed?


....with all the physical details worked out, then as for the electronics....bob's your uncle!

Ken

 

[jpanhalt]

You might get some fresh ideas by studying the work of Dr. Henry Plummer, which was initiated almost a century ago. His system of door flags was hard to beat. Your binary plan (on or off) probably falls short in several respects.

https://en.wikipedia.org/wiki/Henry_Stanley_Plummer

I suspect Ken may know what I am referring to.

John

 

[KMoffett]

...I suspect Ken may know what I am referring to.

John

Worked in a hospital...worked with nurse call systems... at one time.

Ken

 

[jpanhalt]

From your address, I figured you may actually have seen the system developed by Dr. Plummer at the WFMC in Rochester. It was very simple and clever and survived into the 21st century, I believe. No noisy buzzers or flashing lights needed.

John

 

[KMoffett]

The mechanical flip-flag system....used everywhere?

ken

 

[jpanhalt]

Well, maybe not everywhere. And MC may not have been the very first, but I suspect it may have been. It was certainly in practice at MC long before the Plummer building was built. What is really important is that it was actually paid attention to by nurses and physicians alike.

As for buzzers, just ask patients what bothered them most during their hospital stay. It's the noise. They can't sleep.

Initially, it was unclear what this question was about. It now seems to be a surgical center, not inpatient facility. It is still not clear to me whether the notification system is to communicate to patients or to the medical staff. Nevertheless, I see little need for a buzzer.

John

 

[KMoffett]

I think that the UK use of "surgery" is different than in the US.

Ken