Time delay?

[fouchagalaga]

Is there anyway to create a time delay in a circuit without using a time delay chip? I kniow there exists chips to delay the time where electrical current enters a part of the circtuit, but I am wondering if tehre is any other way to do this without using this type of chip. This delay needs to be on a 120V circuit... Any ideas? or if not any suggestions to find a cheap time delaying chip? (Only one i found was a local electronics store for 50$...)

[nezbleu]

How long a delay, and delayed compared to what? It's easy enough to use an R/C circuit for a short delay, but if you want to delay 120V wall current you probably want to build a low voltage delay circuit that drives a relay to switch the 120V.

[fouchagalaga]

Well my father and I built an elevator using old motors and pumps we found at the scrap yard. The pump is a power steering pump that is powered by an AC motor. When the motor starts it already has a load on it and it really doesn<T seem to like that. The load comes from the pressure of the hydraulic cylinder pushing back some of the oil. The delay is to activate a release valve thats going to remove some of the pressure between the pump and the return valve so that once the motor restarts it doesnt have a load on it. And I came to think of it, I think it might be on a 12V DC circuit after all. I only need a one second time delay so that when the motor starts it blocks the valve releasing the pressure and once the motor stops, it opens back up. The problem with the RC circuit would be that you would need to uncharge the cap and that it would delay the current into the valve but not in a, there<s no current into there's a current way, but more of a slowly increasing current... right?

[dave_gerecke]

What you need is a 'hydraulic unloader valve'. If you google search you will find the information about what they are and how they work.

Peace,

Dave

[fouchagalaga]

I already have my valves and everything. I only need to delay when it'll kick in. I don't really want to buy more things :s. I might try an RC circuit... if i can calculate whats the minimum voltage to get a 12V relay to kick in, maybe there's a way to get a delay thanks to a cap put in parallel? When the cap is charged current goes into relay that activates circuit that goes into valve? Can something like that work?

[fouchagalaga]

Finally found a way that will work. Thank you for all replies!

Basically the AC motor has a starter coil inside. When the motor has enough speed that first coil is turned off to let the main coil do its work right? By plugging the valve on the starter coil with a transformer. The time it ttakes for the starter coil to stop is about 1 and a half second so the valve wont have anymore energy and will close back