Need Wiring Help For 12 Volt Motor

[philf]

Snub,

I suspect that the connection diagram you posted for your relay is wrong!

From the Picker website (and in common with most other similar relays):



So, in the diagram you posted the Armature and Normally Open Contact connections are swapped over.

You need to connect the relay as follows:



I hope this helps.

Cheers.

Phil.

[75Plus]

I have been watching this thread and decided to throw in my 2 cents. Steve's' circuit is spot on and the explanation is easy to follow. There are just a few comments I would like to make.

1. Most relay contacts are labeled NC, NO and COM (common ). In this case the motor armature is connected to the common terminals but the relay coil is also called an armature in some designs.
2. In the first schematic the joy stick is shown in the on position while the relay is shown de-energized  which can be a bit confusing.
3. A suggestion: Using a DPDT switch the speed controller can be switched in or out of the circuit which would eliminate the need for a second joy stick.
4. It may be wise to add limit switches on both ends of the travel to protect the drive.

[DMIOM]

.....3. A suggestion: Using a DPDT switch the speed controller can be switched in or out of the circuit which would eliminate the need for a second joy stick......

except that then raises the issue of which joystick to use - latching or non-latching? - unless Sub is going to make his own gates.

and ....

The circuits above have the motor power routed through the joystick contacts. I can't recall the specs for the switches being posted but I suspect they're more likely to to be signal-rated than significant-current-carrying? - in which case you may need an extra relay (and maybe a couple of steering diodes).

And .... re my earlier suggestion (#28) of a user interface, if you have the option of making your own gates, then there's a simple way I've just thought of to use just the one joystick - if your gate is "+" then mount it 45 degrees round so you get an "x" gate  so you could still have up/right (unlatched) = high speed right, down/right (unlatched) = low speed right, etc.

Dave

[bertie_bassett]

ahh yes id put the N/O and N/c round the wrong way..

 looks like you've got it pretty much sorted now though 

one thing im not sure will work with the above diagrams though, is the use of the pwm to power the relay coil. im not sure the relay will like that?

[snub]

Snub,

I suspect that the connection diagram you posted for your relay is wrong!

From the Picker website (and in common with most other similar relays):



So, in the diagram you posted the Armature and Normally Open Contact connections are swapped over.

You need to connect the relay as follows:



Phil.

You are absolutely correct. I screwed up. Again. I think I must have used up all my brain cells.

My lack of proper knowledge of the nomenclature caused me to think that terminals 3 and 4 were the armature.

Terminals 1 and 5 and terminals 2 and 6 have continuity with no power to the coil.
Terminals 3 and 5 and terminals 4 and 6 have continuity when power is applied to the coil.

[vtsteam]

Snub, check and post the switch ratings for the joystick -- should be located on the switches themselves, or online from the company you bought them from.



The PWM output driving the relay could be an issue -- maybe put a cap across the relay to keep it high enough in voltage and smooth. And add a diode in series to keep it from backfeeding anybody else......

Guys, I'm out of further ideas unless we add relays, or logic components, or different joysticks which, kinda gets away from the easy theme using the available components.

Anyway -- best I could do! Time for me to let better electronic minds have at it!   

[snub]

Info from the switches:

Ui:  600V
Uimp:  6kV
240 V  3A
lth:  10A

My motors actually draw less than 2 amps so I should be good there.

[bertie_bassett]

i think those switches should be ok, DC currents are harsher on switches then AC but shouldnt be a huge problem in this situation.

i suspect the switch contacts could have extra's piggy backed on the back of them , perhaps the up and down contacts could be re-positioned?

i dont think your far off with the current diagrams, just a bit of tweaking for that pesky pwm

[vtsteam]

I'm addicted to this problem. I think I'm burned out. Then I look at this thread again and.........

Okay shotgun approach to the PWM relay issue:

Add another power supply.

Could be just a little spare DC wall wart with enough juice to kick in the relay.

Here's the same schematic as before with the relay negative lead detached from PWM , and connected to New Power Supply.

The positive side of the supply hooks to the PWM + side.

[snub]

vtsteam, I appreciate all your help, but I think you have gone far and beyond what I would expect a total stranger to do to help me out. I am starting to feel guilty. But if you are so inclined, please carry on.

That power supply that I showed in the first picture was dirt cheap. $16.00 delivered from China. It even has a "trimmer"? that will set the voltage from 11.5 to 14.5 volts. Vendor calls it a" voltage output fine adjustment."

Here is a link to it in case anyone needs one. Will work on 110V or 220V.

http://www.ebay.com/itm/390838271618?_trksid=p2059210.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

[awemawson]

Those are sold widely as 'LED supplies' on eBay UK. I used that exact model when I fitted that strip led light in my Traub CNC lathe. Seem reasonably well made and good value for money.

[bertie_bassett]

Ok might have got it sorted now. Just one extra part needed,

Rather then an extra power supply, just put the supply to the pwm modual in parallel with the relay coil, and its outputs direct to relay contacts.

That would give you slow speed in one direction, for the other simply put a diode or extra switch between the joysticks switches so that only the pwm gets power, not the relay.

I'm not able to draw it up at the moment as on phone, but can sketch it up later if required.

[vtsteam]

That power supply that I showed in the first picture was dirt cheap. $16.00 delivered from China. It even has a "trimmer"? that will set the voltage from 11.5 to 14.5 volts. Vendor calls it a" voltage output fine adjustment."

Snub, don't feel guilty, I'm just kidding about working on this particular circuit problem! 

Also nothing wrong with your power supply -- I just meant add a very small second power supply -- like a wall wart -- which most people have kicking around from unused equipment.

The second power supply will provide the relay coil with a stable voltage when needed, rather than depending on the output of the PWM to do it, which is a variable voltage.

Since the relay coil doesn't need much power, a small wall wart type power supply of the right voltage and current rating should be easily able to handle the needs of the relay coil. This small supply could even be hard wired and built into whatever case you will be putting your main power supply in (if any).

I actually have a commercial CNC controller that had a big power supply (like yours) for the stepper motors, and a small wall wart to power a circuit board, built inside the aluminum enclosure). I only saw the wall wart when I opened the case of the controller to set some DIP switches for different steppers.

So it really doesn't matter what power supply you have chosen to power the motor, this second small DC supply would only be used to close the relay.

The output of the PWM isn't the best thing to use to operate the relay, since, well, if you turned the control down to zero, the relay couldn't pull in at all. And it may not be able to pull in at speeds higher than that and into your useful range of table travel speeds. So the simple thing to do is not use the PWM output to power the relay.

I suggested a wall wart rather than a diode (and you probably don't know what that is), because you're more likely to have a spare power supply on hand,, and it would be a very simple and straightforward circuit change for you. And easily understandable.

[velocette]

This Works

[Will_D]

Hey thanks for the linky!

Thats a great price for a 150 watt 12 V X 12.5 A psu

In europe I paid about €80 for a 12v x 8A psu to run a beer cooler!

Should help the induction heater project nicely (when I stop blowing mosfets)

Work in Progress sums it up

[bertie_bassett]

had a lil bit of time to play around with a modified circuit and this is the best i can come up with



2 options for the pwm circuit, either an added diode, or an extra switch added on the back of the joystick.

personally id try to modify the joy stick for an extra contact.

vtsteam: i dont think your extra power supply will work as drawn as its putting a permenant supply onto the pwm output so you wouldnt get any slow speed

[vtsteam]

Bertie, I like your diode version. And better than the switch version, since the problem was to do this with joysticks, not switches.

I'm not 100% clear why my circuit would do as you say, but one problem with the drawing (pointed out back a ways by 75 plus) is that I showed the joystick contact as closed and the relay is shown in its un-energized position. This might be why I'm missing what you're saying, because I'm back at the head-hurting stage trying to imagine what happens with the relay energized, or the joystick in the opposite contact (to make the drawn schematic consistent).

Likewise, I'm having a hard time imagining that effect on yours since you used my same schematic. Both need re-drawing. But in principle, I like your diode method.

The easiest change to the drawings to make them consistent, would be to draw the joystick common (arrow) going to the lowest contact rather than the upper one.

[vtsteam]

velocette, yours works but doesn't fit the requirements for a high speed joystick and a low speed joystick, each with a center off position.

[velocette]

The motor is always started on Low speed Then engage the second  momentary switch On the joystick to Give high speed by shorting the speed Pot.
A lot less load on start up than reversing at full speed. Works For Me
Eric

[bertie_bassett]

sorry for the confusion, when  i mention switches, i was refering to the contacts on the joystick itself. in this case there are 4 seperate N/O contact blocks.  easiest to think of them as 4 seperate switches.

vtsteam: your drawing with the joystick closed but relay de-energised is a bit confusing, but dosnt really effect much. The modifications i drew up from your drawings, accounted for this and should work as drawn. ( the origional fast speed would need minor wiring changes, but nothing major)

as iv drawn things it dosnt really matter what state the relay is in, your primarily turning the pwm modual on to power the motor, direction is a secondary affair.



the biggest problem with PWM is that its basically just turning the motor on and off very fast, so if you were to feed a relay with it, it would be going on off on off on off which i doubt it would like at all.
adding a constant power supply onto the same rail would just override the PWM as there would no longer be the 'off' section.

overiding the pwm was basically what my origional idea was, get things moving in the direction required at slow speed, then override the pwm to speed things up a bit!

hope that clears things up a bit.

[vtsteam]

vtsteam: your drawing with the joystick closed but relay de-energised is a bit confusing, but dosnt really effect much.

Well it's my mistake and it does actually show an impossible state, and is confusing when trying to trace what is happening, so I'm claiming it as a problem -- at least for me! 

I believe the PWM version of the circuit (not the high speed version, which is fine) that I showed is just plain wrong as a direct result of mis-reading the circuit, based on my mistake in showing the switch closed and the relay opened. I might be able to re-draw it properly, but I need a mental break from it for a bit. I do like your diode version if it proves out.

the biggest problem with PWM is that its basically just turning the motor on and off very fast, so if you were to feed a relay with it, it would be going on off on off on off which i doubt it would like at all.

Nah, I see the reduced effective voltage to the relay if the PWM is turned down as a problem. not the fact that it's pulsed DC. But that's moot. It's obviously better to feed it straight from a full voltage DC power supply in either case.

hope that clears things up a bit.

They were clear already, so no problem. 

[velocette]

Lets edit my earlier explanation to make it clearer please see the PDF File I Posted on "This Works"

Snub in his original posting shows 2 Joysticks 2 Relays 1 Power Supply 12 volts DC 1 PWM speed control  1 12 volts DC motor

Attempting to use the Existing equipment as indicated for the starting base for this circuit.

The motor is always started on Low speed with the latching Joystick Fwd  Off   Rev.

A lot less load on start up than reversing a relay engaged at full speed.

Substitute the Push Button with the second Joystick with Momentary Contacts

 Then use the contacts On the Second joystick to Give high speed by shorting the speed control Pot to High Speed

The High Speed is maintained as long as the Second Joystick is held Closed.

Eric

[bertie_bassett]

whoops just noticed my diode was in the place 

heres an ammended drawing, iv also redone the 'confusing' relay situation, should be easier to read.

[vtsteam]

Well, Berte, now all the relay contact designations and pin numbers PhilF clarified are wrong.  Look out Snub! 

(I said the joystick wiper needed to be moved to a different position),

Diode in wrong place.............this is getting to be funny! 

I guess we'll muddle our way to something that makes sense.

Kinda like chimps typing up Shakespeare's Hamlet by hitting random keys --  eventually

[bertie_bassett]

Ahh it will all work in sure, iv only put the relay contacts in an energised state. ( although technically thats the wrong way to draw a schematic). Shouldn't go bang.

 I think we've moslty got it now, just need that diode or extra switch adding to the joystick.

In regards to that diode, it will need to be capable of handling  the motor current ( plus a bit extra) as its feeding the power to the pwm modual. So a spec higher then 12V 3A should do the trick.

Its been far too long since I draw up proper drawings, but the knowlage is on there somewhere.