I'm an electronics newbie but I understand most of the vocabulary any how for my project I'm trying to open a 24V electronic valve(works with 18V) for a certain amount of time like for example 3/4th of a second with a Lm555 IC. How would the schematic look like?

 

You need the 555 in monostable mode...

http://forum.allaboutcircuits.com/showthread.php?t=14018

Allen

 

Do you have an 18V source?; AC or DC & is valve AC or DC?

 

Do you have an 18V source?; AC or DC & is valve AC or DC?

Yes, two 9 volts batteries in series and the valve is AC i believe

 

Yes, two 9 volts batteries in series and the valve is AC i believe

Batteries are DC and won't operate an AC device.

 

Batteries are DC and won't operate an AC device.

I've made a simple circuit with the batteries hooked up to a switch and manage to open the valve and close the valve even with it holding back 120 psi. All I want it to do is when I press a momentary button is to open the valve for a certain amount of time

 

How to do what you want depends mainly upon the power requirements for the valve. Post the part number and manufacturer of the valve, or better yet, post a link to the data sheet for the valve. Someone here can help.

 

How to do what you want depends mainly upon the power requirements for the valve. Post the part number and manufacturer of the valve, or better yet, post a link to the data sheet for the valve. Someone here can help.

Orbit sprinkler valve model #57041. I wasn't able to find a pdf of it or at least a link. All I know is it's a 24V AC 50/60cycle Solenoid

 

DC resistance is about 20Ω, so will draw a little more current on DC than AC, 900 mA @ 18V DC.

 

Needs review: Only a little leakage current when off. U2 can be NPN invertor, 2N3904, 555 or 1/2 556 with new #s. Any questions??

 

none so far thanks for all your help!