2014Views54Replies

Author Options:

I am building a TV lift with (hopefully?!) RF and dpdt switch in parallel. But my wiring is not working as expected...? Answered

Picture of

I have the hard wired dpdt switch wired as attached and the relay as per the other attachment (but the incoming voltage to power the board and running through the relays to power the actuator are both 12v and from the same source). I am trying to have both a RF control and hard wired back up in the event of battery failure of controller or unit loss.

Both items work fine when wired up to the actuator alone but when put in parallel there is a real issue with nothing happening. It seems like there is a open circuit which is drawing a large current from the transformer but not doing anything with it. I think it may have destroyed the relays on the board though - no, no fuse in the system less that on the transformer :-( 

I just cannot see the problem but I have found another wiring diagram (also attached but with an actual board shown on it) where there seems to be a whole lot less wiring but  I dont know if this will achieve what I need to do.

I do not want to destroy another relay board by experimenting so would be eternally grateful for a little advice.

Can anyone assist, I am not an electronics expert but a mechanical engineer (could never get my mind around what I could not see!!)?
 

50 Replies

user
steveastrouk (author)2013-05-24

Right then, try this. Look at the photograph, and see where the XX marks are. You need to dremel away the track from the transistor to the line marked. You will need to ADD the components as shown on the circuit diagram, which go between the crosses. The relay side of the connection is on the left of the photograph.

You now have NO need for an "overide" switch, and you have limit switches, which should be wired to OPEN when the action hits the limit. So the UP limit switch stops the up direction relay, the DOWN limit, the down direction relay.

Pressing ANY up switch, or pressing up will make the motor go UP, until the stop is hit. Like wise down.

Select as Best AnswerUndo Best Answer

user
intrance (author)steveastrouk2013-05-24

Steve,

All makes sense, I have to order the diodes from maplin as I live in the Netherlands and I don't know where i can get them over here. Also, i am away on work for 3 weeks but I will give this a go when I get back. Thanks for all your assistance, I will let you know how it goes on a few weeks.

Select as Best AnswerUndo Best Answer

user
steveastrouk (author)intrance2013-05-24

There's a chain there, I can't remember the name though.

Select as Best AnswerUndo Best Answer

user
intrance (author)steveastrouk2013-05-25

Order placed but if you think of the name it may be useful in the future as my next project after this is a diy cnc. There are many great examples here!

Select as Best AnswerUndo Best Answer

user
iceng (author)2013-05-21

Wire them like this.
Send the motor wires output to the separate switched power of the other.

A

Select as Best AnswerUndo Best Answer

user
intrance (author)iceng2013-05-21

Thanks very much but wouldnt this require both switch and relay to be activated (one way or the other) to obtain an output?

Select as Best AnswerUndo Best Answer

user
iceng (author)intrance2013-05-21

Each relay PCB has a power down or normal direction.

Only operating a single PCB is necessary to reverse the motor.

If the REMOTE PCB fails in any position or you lose the remote, then
the OVERIDE PCB can reverse the motor instead !!

I think this is better then paralleling PCBs and getting a short circuit
in two of the four possible position options.

Select as Best AnswerUndo Best Answer

user
intrance (author)iceng2013-05-22

iceng, josehf and steve,

Thanks all for your input, the level of detail and speed of responce is truly fantastic. I need a little more clarity though, sorry, confused.

Do I need to wire as per my attached diagram taking into account both Josehf and iceng advice. What I have just realized is that my dpdt is a on-off-on and therefore has a on off when not pushed up or down (it is momentary not locking). Therefore I don't think the in series as per iceng suggestion will work? It is also not going to act like a 3-way light switch as this would require on two switch positions

If I take josehf suggestion am I not left with the same problem or where in the relays wiring does the dpdt switch go?

Do I even have the hardware to achieve what I want to do? Clearly the current wiring for the relays is shorting out (in two or four positions?) but can this be overcome with the relays setup and dpdt that I have if it is wired differently? If not what do I need to go out an get to make it work (an on-on dpdt?)?

Sorry, I hope I am not being too numb.

Select as Best AnswerUndo Best Answer

user

Do it like this.

The first switch selects remote or manual.

The second switch selects forward or reverse.

Select as Best AnswerUndo Best Answer

user

Brilliant thank you very much. I understand and will post the instructable once complete. You have all been absolute stars.

Select as Best AnswerUndo Best Answer

user
steveastrouk (author)intrance2013-05-23

The only thing left to worry about is the absence of limit switches.

Select as Best AnswerUndo Best Answer

user
intrance (author)steveastrouk2013-05-23

i need to have a think about this, I have the hardware but dont yet know how best to implement. i wanted to get this circuitry sorted first (unless you think that is the wrong way to go?)

Select as Best AnswerUndo Best Answer

user
steveastrouk (author)intrance2013-05-23

I can draw a circuit for you that ticks all the boxes you need here - limit switches, relays, remote switches, the lot, but you'll have to make it !

Select as Best AnswerUndo Best Answer

user
intrance (author)steveastrouk2013-05-24

Steve,

That would be great, I have no problem with the practical aspects and understanding the circuit diagrams, I just do not have the knowledge to deconflict the elements of my idea without causing conflicts. The paper to reality is not (normally!!) a problem.

Thanks very much again,

Select as Best AnswerUndo Best Answer

user
steveastrouk (author)intrance2013-05-24

OK.
Lift up and down, by two remote switches and/or radio control, with limit switches on the lift. No "over-ride" switch, everything Just Works ?

reasonable spec ?

Select as Best AnswerUndo Best Answer

user
intrance (author)steveastrouk2013-05-24

Lift up and down, two switching methods; one RF remote switch (two relays?) with hardwired switch (call it override if you want), with limit switches. Everything just works, absolutely.

Thanks

Select as Best AnswerUndo Best Answer

user
steveastrouk (author)intrance2013-05-24

Happy to cut two tracks on the radio board ?

Select as Best AnswerUndo Best Answer

user
intrance (author)steveastrouk2013-05-24

I have two of them, and i will never learn if i dont try, so absolutely, test me!! :-)

Select as Best AnswerUndo Best Answer

user
steveastrouk (author)intrance2013-05-24

Does the RF thing LATCH the relays on, or are they only on when the buttons on the remote are pressed ?

Steve

Select as Best AnswerUndo Best Answer

user
intrance (author)steveastrouk2013-05-24

It can be programmed to do momentary or latched whatever is best. I currently have it latched but either is fine, just the press of a button.

Select as Best AnswerUndo Best Answer

user
steveastrouk (author)intrance2013-05-24

Momentary might be best, in the condition that the thing ought to be controlled whilst its moving, so fingers don't get trapped. Those actuators can provide a VERY nasty nip.

Select as Best AnswerUndo Best Answer

user
intrance (author)steveastrouk2013-05-24

That's not a problem. I will reset them.

Select as Best AnswerUndo Best Answer

user
intrance (author)steveastrouk2013-05-24

Actually three settings latched A on, B off; A on, A off ; and momentary A on while pressed.

Select as Best AnswerUndo Best Answer

user
steveastrouk (author)intrance2013-05-24

Does the radio only hold the relays on when the remote button is pressed ?

Select as Best AnswerUndo Best Answer

user

Or do it like this.

The first switch selects remote or manual.

The second switch selects forward or reverse.

Select as Best AnswerUndo Best Answer

user

I cant flag this up as the best answer but I truely appreciate your time and effort, thank you

Select as Best AnswerUndo Best Answer

user
steveastrouk (author)iceng2013-05-22

I'd hack the coil drivers for the relays if it were me.

Select as Best AnswerUndo Best Answer

user
steveastrouk (author)iceng2013-05-21

Now all you have to do is tie in the remote and you're done.

Select as Best AnswerUndo Best Answer

user
Josehf Murchison (author)iceng2013-05-21

Iceng
I am surprised you did not see the relays weren’t reversing.

Select as Best AnswerUndo Best Answer

user
iceng (author)Josehf Murchison2013-05-21

You covered that very well.

It was more important to prevent intrance from paralleling the relays
and the short that it would cause, so it got the first action.


Select as Best AnswerUndo Best Answer

user
Josehf Murchison (author)iceng2013-05-21

I like yours it is like a light switch you can turn on or off from any room.

Select as Best AnswerUndo Best Answer

user
iceng (author)Josehf Murchison2013-05-21

Very perceptive, of course you have wired 3 or more light switches before :-)

Select as Best AnswerUndo Best Answer

user
Josehf Murchison (author)iceng2013-05-21

I have wired a lot of houses.

Once a hydro inspector asked why I used a marret and electric tape on all my connections, don’t I trust the marret?

I told him I don’t trust my mother and she been dead for ten years, my electrical passed the inspection.

Select as Best AnswerUndo Best Answer

user
iceng (author)Josehf Murchison2013-05-21

That's a new one, never heard wire-nuts called Marretts.

But in older buildings with old wire, I tape over too.

Select as Best AnswerUndo Best Answer

user
Josehf Murchison (author)iceng2013-05-21

Opps spelt them wrong. Marrettes

At least you got the spelling closer than me.

Select as Best AnswerUndo Best Answer

user
steveastrouk (author)2013-05-21

Can we see a good photo of the BACK of the PCB. You're going to have to modify that. I'm not surprised that connecting the switch has fused the relays !

Select as Best AnswerUndo Best Answer

user
intrance (author)steveastrouk2013-05-21

Both front and back added for completeness

Select as Best AnswerUndo Best Answer

user
iceng (author)intrance2013-05-21

Does your remote allow you to switch only one of the relays
and not the other ??

A

Select as Best AnswerUndo Best Answer

user
intrance (author)iceng2013-05-22

Yes, which is why I had the wiring in the intial layout.

Select as Best AnswerUndo Best Answer

user
steveastrouk (author)intrance2013-05-22

Which lift have you used ?

Select as Best AnswerUndo Best Answer

user
intrance (author)steveastrouk2013-05-22

I have used a stock actuator from ebay, 12v, 600mm lift, it does not seem to limit switches inbuilt. It is a project to build a lift from scratch (once complete instrucable to be posted, I am compiling at the moment). All I seem to be able to find is X frame lifts people have built or 'how to install and ready bought lift' so I though go out and build one yourself!!!

Select as Best AnswerUndo Best Answer

user
steveastrouk (author)intrance2013-05-22

It HAS to have limit switches in it - else it would blow the fuses every time it hits the ends ! Have you a link ?

Select as Best AnswerUndo Best Answer

user
intrance (author)steveastrouk2013-05-22

It is a LINAK LA28 as per link:

http://www.kramp.com/shop-de/en/11451/45698/578387/0/Linear+actuators+LA28+LINAK

No limits, the lifting head starts to spin once the actuator reaches one of its limits and continues to spin without lifting or dropping.

Select as Best AnswerUndo Best Answer

user
steveastrouk (author)intrance2013-05-22

It would be better to incorporate limit switches in the design IMHO....

Select as Best AnswerUndo Best Answer

user
intrance (author)steveastrouk2013-05-22

Was planning to do this in the frame (activated by the moving drawer sldies) and I have them sitting on my workbench but that would go into the wiring of the relays and switch and until I can get the RF and hard wired override to work then I am staying clear of increasing complexity (that clearly I cannot get my head around) quite yet!! ;-(

Select as Best AnswerUndo Best Answer

user
Josehf Murchison (author)2013-05-21

Change your wiring to this.

Select as Best AnswerUndo Best Answer

user
iceng (author)Josehf Murchison2013-05-21

A nice feature of this wiring if the RF control allows individual relay activation is :
that the motor can be switched off in addition to reversing !

A

Select as Best AnswerUndo Best Answer

user
steveastrouk (author)iceng2013-05-22

You can bet there are actually limit switches in the motor end,else there is nothing stopping it !

Select as Best AnswerUndo Best Answer

user
iceng (author)steveastrouk2013-05-21