Charles Linburgh deadmans button

[ecopure]

Hi everyone, just joined and love the place.

I've been trying to figure out how to make a timing circuit that will stay "latched" as long as someone pushes a button every 10 minutes. If the button isn't pushed the timing cycle stops and an alarm goes off.

When Linburgh flew across the atlantic he had alarm clocks to do this. I would like to make one out of a 555.

Any help would be appreciated

Thanks
Steve

 

[Mikebits]

I live near Lindbergh airport so you caught my attention Sounds like you need a retriggerable one shot. This part will do what you want.
https://www.electro-tech-online.com/custompdfs/2010/03/74HC_HCT123.pdf

 

[MikeMl]

Hi everyone, just joined and love the place.

I've been trying to figure out how to make a timing circuit that will stay "latched" as long as someone pushes a button every 10 minutes. If the button isn't pushed the timing cycle stops and an alarm goes off.

When Linburgh flew across the atlantic he had alarm clocks to do this. I would like to make one out of a 555.

Any help would be appreciated

Thanks
Steve

Here you go. Output goes high on the first trigger, and stays high only if the button is pushed before the 555 times out. It is set for about ~600sec. R2 is there to limit the discharge current through the switch.

 

[RCinFLA]

Just don't fall asleep leaning on the push button.

 

[haris_216]

Here you go. Output goes high on the first trigger, and stays high only if the button is pushed before the 555 times out. It is set for about ~600sec. R2 is there to limit the discharge current through the switch.

nice circuit. am really curious as to why ecopure would want it in the first place. I mean, atlantic has been crossed more than once so far, right?
i have one suggestion though. I think that one kind of warning (visual or audio) that 555 is about to time out (giving 20 seconds for example) would be helpful

 

[bryan1]

I think that one kind of warning (visual or audio) that 555 is about to time out (giving 20 seconds for example) would be helpful

Perfect job for a 8 pin lowend pic, just use this pic delay calculator
then assign a led, push button and a piezo to a few pins and away you go....

Cheers Bryan

 

[ecopure]

Thanks everyone! Very simple Mike.

Thanks

 

[schmitt trigger]

This is still used on railroads.
If the engineer falls asleep (or something worse happens to him) an alarm goes off. If it goes unattended for another period of time, the brakes are then applied.

 

[flat5]

I need one too but the time required is 108 minutes and you need to enter the code 4 8 15 16 23 42.

(just kidding)