Controlling a solenoid with a triac

[The Master]

Hi, Sorry ive been posting a lot of threads lately. Halloween is coming so im trying to learn a whole load of new stuff.

The problem this time is with my water solenoids. Im using triacs to control them. They are turning on fine but they wont turn off until i cut the mains power. Its a bit like when you try to use one on DC but im actually using 240V AC so i dont know why i have a problem.

[The Master]

I managed to solve this one myself. For some reason it works if i put something else in parallel with the solenoid. Im actually using one of the lights for my smoke machines that tell you when you can press the button. Seems to be working fine as long as thats connected.

Does anyone know why this is happening and have any better ways to fix the problem?

[mackrackit]

Here is a guess.
A TRIAC has to see 0 to shut off. The solenoid with inductive feed back is some how not letting 0 be seen.

Adding a parallel resistive load is allowing the TRIAC to see 0.

Like I said, just a guess.

BTW..COOL avatar.

Happy Halloween.

[The Master]

I was thinking something along those lines. I have a low voltage solenoid to move the grim reapers mouth. Its DC but i connected AC into a triac then rectified it after. That one is fine but i guess the rectifier or the fact that its low voltage helps that one out.

This must be the earliest that everything has been working and this time the circuit isnt resetting itself because everything runs through triacs instead of relays.

Heh, I made an animated gif (http://www.spooktech.org/avatar.gif) that fades between my normal avatar and my halloween one like yours but the forum wouldnt let me upload it and it wouldnt let me link to it from my site either. I think the static one looks good enough though.

[Darrel Taylor]

Triacs have a minimum Turn-Off current.
If the solenoid draws less than that current, it won't turn off.
It's usually stated in the datasheet, but some just show a range (.2 - 5A) or similar.

And, yeah the forum has a problem with animated avatars right now.
Started after the upgrade.

If you want, I can upload it for you.

DT

[The Master]

I guess that could be right. These solenoids say 6VA which i work out to be 0.025A. I thought it was the other way round though. I thought they wouldnt turn *on* unless you have enough load on it. Come to think of it, it does make more sense that it affects it turning off.

Dont worry about the avatar. Im happy enough with the static version.