Timer Circuit. Need Help

[justin312]

Hey guys, I'm new to this forum but I need some help with a project.

Basically I have a pneumatic solenoid that's being run to a 12v DC power source and is triggered by a simple momentary push button switch. What I need is a timer or something where I can switch it on and after a 3-5 second delay the power goes to the solenoid which causes it to open. Any help would be appreciated and I can compensate the first person to send me plans for a prototype. I'm not very good with regular schematics so you'd have to dumb it down for me. (I'm a mechanical engineer by trade.)

Also the overall dimensions cannot be larger than 2.5 cubic inches.

 

[KMoffett]

Sounds like a job for a LM555 timer chip. What's the current requirement for the solenoid? Does the solenoid remain on until the 12V "system" power is removed? Is this an automotive application?

Ken

 

[swilsonNC]

I am assuming he doesn't need it to stay on since he uses a momentary push button now. He will need to put a relay on the output to feed the solenoid probably.
I have a circuit I just soldered you can try.

View attachment 63361
View attachment 63362

In this schematic change R3 to change delay time and change R8 to change the on time of the relay on the output.

I don't know if this is what you are looking for but if it is you are more than welcome. if not, well we tried.

 

[KeepItSimpleStupid]

I would have a few questions:

1) Define momentary
a) Like a 10 millisecond push/edge trigger -or-
b) Hold button, and in 3-5 seconds it turns on.

Aside: I know you said momentary, but you also said switch it on. Your NOT looking for something that uses a on/off switch, but delays the power 3-5 seconds?

2) Define the current at 12V

4) clarify 2.5 cubic inch rule
a) If a relay was used, does the 2.5 cubic inches include it?

Aside: Solenoids don't "open" unless they break. They may "pull-in" or "activate". The solenoid could "open something" like the trunk.

 

[swilsonNC]

Will be interesting to see his reply. I bet he has to hold it for the 3-5 seconds so everything gets going. If that is the case a simple timed one-shot would work.