Jump to content
Electronics-Lab.com Community
Sign in to follow this  
bonanz

time delay/ hold circuit

Recommended Posts

I know this is something simple but i've done a little searching and can't find what i'm looking for and i can't work it up form scratch for the life of me....

I'm looking for digital logic circuit/gate that everything starts at 0 (low) and then if high is input, the output is high, but only for about 5 seconds, then the output goes low again, nomatter if the input stays high or goes low again.

I hope i explained it clearly, but basically the idea would be, press a button to turn on a LED or something for 5 seconds or so, if you hold the button down it goes for 5 seconds and turns off, if you press it and let go it will hold it for 5 seconds and turn off, either way once the led goes low it is ready to be turned on again.

Thanks in advance guys

Share this post


Link to post
Share on other sites

Hi,
what you need is a 555 timer ic, in "non retriggerable" mode.
If you "google"( 8)) with the words "555 timer" you'll find about
54.000 results :D.The http://www.williamson-labs.com/480_555.htm
for example,looks good.
Hope i have helped a bit. ::)

Share this post


Link to post
Share on other sites

As manotronic noticed you can use a 555 timer in Monostable mode:
The basic circuit is this:



For circuit description and how to attach a relay visit: http://www.technologystudent.com/elec1/5554.htm

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
Sign in to follow this  

×
×
  • Create New...