Auto reversing polarity after a few milliseconds (for solenoid control)

Hbridge.......but there will be other considerations you probably haven't thought about.....inductive reactance ....time for solenoid to physically move being just a couple....i doubt the armature will get very far in a few milliseconds

 

1. Any idea what the steady state current through the solenoid coil is?

2. There is nothing in the valve description that mentions having to reverse the current through the coil. Are you sure this is necessary?

ak

 

Yeah, I read those specs too and there's absolutely nothing in the description that so much as hints that reverse polarity is required or is even relevant for its operation. In fact the description indicates a typical "Pulse On - Pulse Off" logic. Unfortunately the specs fail to specify the required minimum pulse width to change states.

Chris

 

You could use 2 simple single pole momentry changeover switches(microswitch for example)
Other than that the H bridge I mentioned in #2 if you plan to run a microcontroller for some such reason.

 

I googled your valve's PN and got quite a few hits. Unfortunately the ones I read describe its operation identical to the link you provided; Pulse Open - Pulse Close.
http://www.plumbingsuppliesexpress.com/item/5933559/

Since your empirical tests prove otherwise just sit tight and wait for solutions from EP's membership. One of us will undoubtedly provide you with the most practical solution. Are you looking for a total DIY or are we to limit our suggestions to 'Plug & Play - Off The Shelf' solutions?

Update: I was just about to click "Post Reply" when I decided to read the reviews in the link I provided above. The first reviewer describes the valve's operation exactly as you do.
https://www.amazon.com/dp/B00YVIE9LI/?tag=leo-lk-20&ie=UTF8#customerReviews

Sorry for inferring that you're misunderstanding its operation but the product description is rather sparse and obviously in error. Since none of us has your valve we have to rely on what the supplier or manufacturer specifies.

Chris

 

Sorry for persisting in this but we're a tech forum and we don't like leaving mysteries unsolved. I found a U.S. seller on Ebay that list your solenoid valve. His description of operation is exactly like all I've read, including yours. I messaged him to ask why reversing the polarity is not specified.

http://www.ebay.com/itm/U-S-Solid-3...-Latching-Solenoid-Valve-DC-6-V-/302030049110

Chris

 

It would appear that the Ebay seller is not going to respond to my query. No matter though because I believe Harald posted a solution in this post...
https://www.electronicspoint.com/th...nds-for-solenoid-control.280361/#post-1705652
Just follow the link he provided.

Chris

 

Frustrating, isn't it? I've bounced this around in my head to the point of getting a headache. Perhaps we're missing something? I've noted that the users (like Adam) have made their test 'dry'. The specs indicate it's a unidirectional valve which might hold the answer. Is it possible that the latching mechanism might require fluid or air pressure to operate properly? IE, without reversing polarity?

I tried sketching an electromechanical circuit that would mimic this action but it just makes my headache worse. Besides, too much brain strain violates item (1) on my retirement 'Don't do' list.

Chris

 

The valve is described as a magnetic latching type, which suggests its function is like that of a single-coil latching relay. Such relays require energisation pulses of ~10mS, the 'reset' current being the reverse of the 'set' current. Because the valve armature inertia is greater than that of a typical relay I would guess the valve pulses might need to be >10mS.

 

Taken from the specs........
Magnetically Latching 2 Way 2 Position Solenoid Valve
ACTUATION: A short 6 Volt pulse lasting only 50ms can open/close the valve

As for whether or not it requires reversing the coil power, it would depend on the internal mechanism.
I remember the old "bed lamp switch" which is press for on and press again for off.(latching)
Maybe this has a similar mechanism internally.

Also there is this.....
Direct Operated/ Pilot Operated:.......Semi-Direct

 

The review I read on Amazon stated that the seller advised pulse times about 50mS.
https://www.amazon.com/dp/B00YVIE9LI/?tag=leo-lk-20&ie=UTF8#customerReviews

Chris

 

From scratching around on the web it seems the power requirement for a similar valve is ~2.2W, implying a coil resistance of ~15Ω (but unknown inductance). The touch sensor spec says the output switch provides an output voltage equal to the supply voltage at up to 10A and can be configured as a toggle (i.e. one touch for on, one for off).
Based on those figures and an assumed coil inductance of 100mH, this simple circuit should do the trick. C1 might need to be a tad higher value.

 

My post 16 circuit relies on the output switch of the sensor being a push-pull type with the ability to pull down to ground. If, instead, the switch is a normally-open high-side-only type, then that circuit won't work and something along the following lines would be an option :-

 

When I quoted the old type bed lamp switch it was a means to describe what might be going on inside the valve. Was not meant that you should use it as a switch for your device.