How to make solenoid as in reverse operation?

[xiaobai00]

I have a problem here. May i know how to reverse solenoid operation? Example when i switch on power supply, the solenoid must be operating at open instead of close logic. Or i use NPN phototransistor to include the circuit. When i switch on power supply, phototransistor will be detected by light and make solenoid unlock instead of locking.

 

[HarveyH42]

Different types of solenoids, push, pull, rotory... How you physically mount the solenoid can determine its function. Electronically, some are continous duty, some intermitten. No idea what you have, or what you are doing with it.

Is it a valve (open/close logic)? Use an inverter...

 

[xiaobai00]

Normally when i switch on supply, the solenoid operate at forward bias (lock ). For this case, i want solenoid operate at reverse bias (open). Use an inverter at where?

 

[audioguru]

A solenoid only pulls iron. A DC current in a solenoid will push or pull a permanent magnet the same way a speaker works. Reverse the DC current or reverse the magnet and the direction changes.

 

[Leftyretro]

xiaobai00;

Most DC solenoids (as well as AC solenoids) I've worked with at work and at home are non-polarized in nature and operate much like simple DC relays, which pull on the soft-iron follower no matter the polarity of the DC voltage applied to the windings. Reversing the polarity does not change the 'action' of the solenoid.

Most solenoids (same as simple relays) I've used have a spring to bias the mechanical travel to the non-energized direction, so I see no easy way to reverse that action.

Some simple solenoids operated valves come with 3 'ports' that duplicate the SPDT action of relay contacts such that one can pipe up the fluid or gas to pass or block flow depending on the solenoid coil being powered or not, so one has the option of 'reversing' the action just like one has the option on a relay by using the normally closed contacts Vs the normally open contacts.

I do have some small DC latching relays that use a single coil where one polarity 'sets' the relay and the opposite polarity 'resets' the relay, however that is because the internal follower is magnetic and has a north and south pole that is attracted or repelled from the relay coil depending on the polarity applied to the coil.



Lefty

 

[xiaobai00]

what i mean is how? I just want the procedures, is that possible to make solenoid reverse?

 

[Hero999]

We've just explained all you need to know.

We don't mind if you ask questions regarding the replies but there's no point in simply asking the same question again; the only thing you might achieve by that is another red square.

 

[jpanhalt]

what i mean is how? I just want the procedures, is that possible to make solenoid reverse?

Extend a rod from the solenoid center piece through the back side of the coil. Then turn it around. Now, when the solenoid pulls in the center iron piece, the extended rod will push.
John

 

[xiaobai00]

i still cant get it reverse. Can anyone post the circuit as sample or reference?

 

[jpanhalt]

i still cant get it reverse. Can anyone post the circuit as sample or reference?

Perhaps if you will describe what you have done or give a picture, we may be able to help. As noted by everyone, you cannot reverse the solenoid electrically, so I gave you a mechanical solution. Have you tried that?

 

[sandwichx]

Connect your signal to the coil of a relay. The relay will have two sets of dry contacts, normally open and normally closed. Just connect the solenoid to the function you want.

 

[Papabravo]

This is not a problem of relays and contacts. He wants an electronic way to make a solenoid move in the reverse direction. Listen very carefully. IT CANNOT BE DONE BY ELECTRONIC MEANS.

 

[Boncuk]

It's easy to reverse action of a solenoid. Take a look inside the electric part of a model train track switcher (sorry for the incorrect choice of technical terms, I'm German).

The solenoid has two windings with a center tap. Activating either one will move the iron bar in one direction, activating the other part will reverse movement. To hold the desired track the device is locked with an over the center spring acting like a lock not allowing any force on the levers to move by itself, allowing to deactivate the electric circuit and hold position.

Over the center locking is used in many applications like the retractable gear in airplanes.

 

[Boncuk]

Listen very carefully. IT CANNOT BE DONE BY ELECTRONIC MEANS.

Hi PapaBravo,

let me partly object to what you stated. If the direction is reversed by electronic means solely it also means a steady current flow through the solenoid. Solenoids however are constructed and built for short time operation only and sooner or later they will burn up. Using a mechanical latching device will outnull that problem.

Play model railroad from time to time. It helps!

 

[Leftyretro]

Hi PapaBravo,

let me partly object to what you stated. If the direction is reversed by electronic means solely it also means a steady current flow through the solenoid. Solenoids however are constructed and built for short time operation only and sooner or later they will burn up. Using a mechanical latching device will outnull that problem.

Play model railroad from time to time. It helps!

Boncuk:

Your are not helping the original poster with his problem. A model RR rail switcher is not a normal simple solenoid, so does not apply to his question.

Also one can obtain solenoids that are rated for continous power on duty as well as ones rated for only momentary service.

 

[Boncuk]

Your are not helping the original poster with his problem. A model RR rail switcher is not a normal simple solenoid, so does not apply to his

At least it was an approach to reverse action. Connecting two of them in series and using the center tap for one polarity and alternatingly activating one solenoid he'll achieve the desired function. Using solenoids for continuous operation he can skip the mechanical locking.

Using a permanent magnet rod inside the coil he can also reverse action by reversing polarity.

So what's wrong with it? Everybody - including myself - has clearly pointed out that there will be no chance to reverse action with a normal simple solenoid.

 

[Papabravo]

Since we don't have much of a clue as to his application it's really hard to say what will and won't work for him. He did turn his nose up at the mechanical solution so who can say what he's up to.

 

[saturn1bguy]

Boncuk:

Your are not helping the original poster with his problem. A model RR rail switcher is not a normal simple solenoid, so does not apply to his question.

Also one can obtain solenoids that are rated for continous power on duty as well as ones rated for only momentary service.

1) Agreed. The model railroad turnout (switch) is not analogous with most solenoids.

2) Many solenoids that are rated for continuous duty sport a potted electronics module which electronically switches from a pull-in coil to a holding coil (two wires to three).

 

[saturn1bguy]

He wants an electronic way to make a solenoid move in the reverse direction.

Are we sure of this?

Xiaobai00, do you want the solenoid to:

1) mechanically move forward instead of backwards, or
2) do you want the solenoid to turn off when it now turns on?