Continue to Site

Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

"TIMED" Power on delay circuit.

Status
Not open for further replies.

haxxx

New Member
I've built this power on delay 555 circuit which works just fine.
However what i need is a timed power on delay.
That is, after switch is pressed there is a 5 sec delay,
then relay latches for 5 seconds then deactivates, ready for another switch press.
I tried using a 10 sec 555 timer before the "power on delay 555" circuit,
that is: pin 3 of the 555 timer will provide vcc to pin 8 of the "power on delay 555". seems crude i know, novice.
For some reason this cancels the timing circuit in the "power on delay 555" circuit,
load just stays on.
Any ideas, would be appreciated.

Regards,
Richard
 

Attachments

  • LM555PowerDelay.jpg
    LM555PowerDelay.jpg
    26.6 KB · Views: 3,957
if i understand you correctly, you need an on and off dleay timer with one switch.. when the switch is pressed the relay lathces after 5sec and then relases after another 5sec?? if so you can add a 4017 counter together with your timer to get right out put, also 555 itself can do it for you as i beleive..
 
I'm thinking two 555 timer monostables set for 5 seconds each. The push button activates the first timer, then the negative edge of its output activates the second which turns on whatever for five seconds.
 
Last edited:
I believe what you want is a Two Stage Timer consisting of a pair of One Shot timers where the output of the first following a delay, initiates the output of the second timer. Pretty much as colin mac suggest. This can be done using either a pair of 555 timers or a single 556 timer. Attached is a somewhat yellowed image of what you want. Credit to Forrest M. Mims III as this was taken out of a very old copy write 1982 Engineers Notebook authored by him.

You will need to select the timing components to suit.

Ron
 

Attachments

  • Two Stage Timer.gif
    Two Stage Timer.gif
    1.1 MB · Views: 659
Last edited:
Timed delay

See if this is what you are after.

Sorry Ron. The scanner is faster than the mouse.
 

Attachments

  • delay on.PNG
    delay on.PNG
    81.4 KB · Views: 514
Last edited:
See if this is what you are after.

Sorry Ron. The scanner is faster than the mouse.

Actually I had the scanned image in a file. :) However, yours is indeed much better than my image of a yellowed 30 year old drawing on a quadrill pad. I figure the OP will get the point.

On a side note I need to get my scanner working again. It works fine on the wife's system and my workstation but refuses to work on this, my everyday system where I need it. Everytime I want a scan I need to connect to Kathy's system, do the scan, then move the files across the network. PITA! :)

Ron
 
thanks a lot guys, I ended up going with the Two Stage Timer. Output of timer A connected to the trigger of timer b through a .01 cap.
Works great. appreciate the help.


haxxx
 
Good Haxxx!

Ron, Between the 2 of us we could make 1 scanner. I have the opposite problem with Becky.
 
will it work with a momentary trigger of the switch? or need long press??
I have absolutley no idea. I just design and draw the circuits. I don't know anything about electronics.
 
Status
Not open for further replies.

Latest threads

New Articles From Microcontroller Tips

Back
Top