help me with delay relay

[XFOX]

I want to put some sort of delay relay so that when i turn my computer off the fan/pump on my system keep runing for 30/90 seconds. I know its possible but how?? :think:
i have some experience with electronics (not expert but close)
if someone could even post the circuit board diagram and the parts I would be happy enough
:bowdown:
Thanks in advance and modd till you die :dead:

[XFOX]

I was doing some searches and i found that i might need a transfer switch this way when the power supply turns off it switches to a adaptor and then i use the timer along with the external adaptor but how am i going to get a transfer switch is ther a way to build one?

[Luke122]

What about using a capacitor? It will continue to power the devices until the power is drained from it.. it's essentially a battery. The only problem is that on startup, it make take a few extra seconds before powering up the device connected to it. Not exactly a good idea for a cooling system.

[XFOX]

its not a bad idea but i dont think that it would power 2 fans and a pump for too long but thanks every help is good to clear my mind to the different ways, i am going to try to put a relay when the power is cut off it will make contact ad will activate a timer with external power(not psu) maybe it will work

[OvRiDe]

Here are some pages that may have some useful timer circuits..

http://home.cogeco.ca/~rpaisley4/LM555.html#20
and on the same page
http://home.cogeco.ca/~rpaisley4/LM555.html#30

http://www.aaroncake.net/circuits/relaytim.asp

Here is something that might work for you as a prebuilt unit..
http://store.mp3car.com/Automotive_Shutdown_Controllers_s/9.htm

Its designed to be used for a PC with in a car, so that you don't have to wait for the OS to shutdown before you turn the car off.


The uSDC also provides a timing mechanism that is user selectable allowing the computer to remain “on” for an amount of time after the ignition has been turned off.

My guess is you could hook one of the power supply outputs to the circuit (simulating the state of a car's electrical system) and use the supplied high current relay to power the cooling system. When you turn the computer on, the 12V output would turn on the circuit as if the car had been turned on, and when you power off the computer, the circuit would interpret that as the car being turned off, and the relay would continue to power the cooling system for as long as the delay was set and then power off. But there is a catch.. you will not be able to use the computers power supply to power the cooling system. In any case this would be the problem with any timer circuit solution, since I don't think there is any way shutdown a computer and still have the PS on. But really that is not really a problem either, all you would need to do is use some sort of external type 12V power supply to run the cooling system. I would recommend something like a laptop charger type or some of the older LCDs had an external power supplies. They can usually handle a bit more current then your standard wall wart.

Here is an example of what I am talking about..

http://www.mini-itx.com/store/?c=10#ac60

Anywho.. hope this helps and good luck!!

EDIT:
After my post I came across this..

http://www.ics-timers.com/off_delay.html

Looks pretty simple and would work with a relay.

or http://www.ics-timers.com/op4142.html might have it already built into a relay.

Just not sure of the price or how to get a hold of either of those buggers..

[XFOX]

thanks alot ill give it a try im short on time here but defenitly ill give it a try

[XFOX]

i was having a look and i had a idea ill use a relay conected to the psu the current will go trought normal but when psu is turnd off the relay will switch to the timer circuit wich i alteady have thanks alot for all your help maybe it will work

[XFOX]

after some research i found the Double Pole Double Throw relay this way the pc psu will power the coil when turned on when i turn the pc off the relay will change because there is nothing powering the relay and when changes over will start the timer (probably 3/5 minutes) i already got a timer but i might improve it and put everithing including relay(need to get 1) on a nice tidy box(need to get 1 aswell)thanks alot OvRiDe and Luke122

after i finish this small project ill post the results because someone might want to try the same thing as this will improve the lifetime of the components specialy if they are overclocked

[XFOX]

after all im useless without the help of the gurus of electronics the problem now is that the button on my timer is suposed to be pressed momentarly but the relay works as permanent switch what happens is that everithing is working ok but the timer dosent turn off after the time elapsed. is ther a way to fix this?

[OvRiDe]

What did you use as your timer circuit? Was it a scratch build or something you adapted?

Here is a very simple time delay circuit that uses a transistor, a couple of diodes, and a resistor. I am no electronics guru, but this looks pretty promising.

http://www.circuitdb.com/show.php?cid=93

http://www.circuitdb.com/downloadimg.php?fileID=206

Good luck and let us know how it works out.

[XFOX]

i used this http://www.maplin.co.uk/Module.aspx?TabID=1&ModuleNo=3315&doy=17m3 amd i would lke to keep this the problem is just the switch momentary permanent thing is ther a way to put something between the relay and the timer to make it momentary?

[crenn]

What happens if you have the switch pressed down?

[XFOX]

if the switch is pressed down when the time elepsed starts again in a split of a second and just keeps going on .what i need is something between the relay and the timer to make a momentary contact

[crenn]

Those switches rely on a 5v rail. There is 2 switches correct? One for start another one for stop? If so, I might be able to learn a couple of logic gates for this.

[XFOX]

finaly found one timer that sems to work :banana: got it set to 3min not bad thanks OvRiDe for the link i wasnt going to build the timer because i was going o use the other one that i had but decided to build this first one on the image http://home.cogeco.ca/~rpaisley4/LM555PowerDelay.GIF
now just need to add the relays and put everithing on a nice box and get conectors to put on the box when i finish all this ill post the diagram of the hole thing

thanks alot for all your help and ill give some news about the full circuit working in a week time when i get all the stuff

.

[XFOX]

this is what im building does this make any sence ? :D


http://www.freewebs.com/50centxfox/File0003.jpg

if something is wrong or may be improved please fell free to help me

thanks
:banana:

[xmastree]

Damn, an electronics thread and I wasn't invited...

First question, what power do the pump and fans require? If the PSU has shut down, where do you plan to get it from?
The simplest idea would be a capacitor, as Luke suggested. But it would need to be a F-BIG one (and I don't mean Fairly...). This would also (as has been suggested) give a slight power on delay but I don't think that would be a problem as the temp doesn't shoot up to max in the first few seconds.

So, what power (voltage and current) are we talking about here?

[XFOX]

there is 2 inputs one from the psu and other from a external adaptor when the psu turns off the relay will turn on the 2nd circuit and the pump/fans dont even turns off its just a split od a second and the timer starts counting down after 2/3 min everithing turns off

[Woztron]

I remember seeing some thing on the net some where a program that holds the computer mid shut down for you desired length of time before final switch off. Made for o/c'd comps to run the cooling for a bit at minimal load when you shutdown the machine. Kind of a turbo timer like in a car.