Hello, I was hoping you all could help me out.



I'm looking for some basic electronics help. Let me describe the application first.



So we have a door with a magnetic strike that is connected to our phone system. We can open the door by typing a code on the phone, the only problem is the strike is silent when it opens, so people don't know when to pull on the door. I would like to place a buzzer inbetween the switching mechanism and the strike that sounds when the door opens. But since the strike is open for say 5 seconds and I don't want the buzzer sounding for 5 seconds I run into a problem.



So what do I need to do to add a buzzer that will only give a short buzz? The circuit the strike is on is 12 volts.



Help is greatly appreciated!

 

Hi,

You could acheive a short beep by using a 'one-shot' circuit between the 12v 'open signal' sent to the magnetic strike and a small buzzer.
Take a look at here: Circuit - PUSHBUTTON ONESHOT AND LATCH/b> - Circuits designed by David A. Johnson, P.E.

The top circuit will give a short pulse every time the input goes high. (You would need to remove the switch, and have the 12v feed go directly to where the switch was)

Hope this points you in the right direction.

__________________
'Intellectuals solve problems. . . Geniuses prevent them.' . . . Albert Einstein

 

Instead of a noisy buzzer maybe you can light a green light.

__________________
Pay it forward.

 

lights is a good idea and you will not be a problem if light emits for more than 5 seconds

 

Yes, but will it meet requirements for handicapped (blind) accessibility.

Just picking nits here.

Ken)

__________________
"To invent, you need a good imagination and a pile of junk."
Thomas A. Edison (1847 - 1931)

 

Come to think of it, would the buzzer option meet the requirements for DEAF people? (sorry, people with hearing impairment)

Political correctness has gone mad. we can't do anything without offending someone.


Maybe you should just employ someone to open the door for everyone

__________________
'Intellectuals solve problems. . . Geniuses prevent them.' . . . Albert Einstein

 

I thought about using a light, but seems like a buzzer might be better. That will be my second option if I cannot figure this electronic schematic out.

 

I thought I would put my post in here for Basic Electronic help.

The Book that I have to try to Teach myself Electronics says to findout the type of Resistance your Circut needs the formula is this.

R = E over I

Then it explanes a Basic Flsh Light ware the Bulb isthe Load and it would then be the Current.

And the Battery would be the Voltage and to findout the kind of Resistance you need you take the Battery Voltage and Divied it by the Load Current.

So I am making a Flash Light out of a LED and my LED is Rated at 2 Volts and needs 40 mA to light.

And I am going to use a 9 Volt Battery.

So I thought I could use the same formula since I know my Load needs 40 mA Current and the Voltage I will have is 9 Volt Battery.

Then R = E over I

9 Volts Divided by 40 mA = the Resistance I will need.

Just tell me if this works for the Flash Light why can't I use this formula for my LED it will be the same thing as what is in the Book for the Example??????

 

Why not have something on the door (if it isnt too heavy) that just nudges it ajar?

 

That seems a lot more complicated then a simple buzzer. Also, the door is heavy, so i don't know how easy it would be to do that.

 

Maybe, that "something" could just be a spring - though the door would then have to be "shut to" everytime it needed closing.

small explosives attached to the door hinges? only joking