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Controlling a Fog Machine


paulcav151

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Ok just found these can some one tell me if they will work. They both have diodes inside of them but each one has the diode going a diffrent way. So will some please look at these and tell me which one to get if they will even work at all. Also could some one just explain how the dirrection of the diode matters and what you use each dirrection is used for. Sorry for all the questions

http://www.delcity.net/store/Change-Over-Relay-!-with-diode/p_73580.h_74257.a_1.t_1

http://www.delcity.net/store/Relay-!-with-diode/p_73578.a_1

Thanks

Ben

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ogamoga wrote:

Ok in adittion to me wanting to know how many amps my relay needs to carry are you sure about how you told me to attach the diode is right because I saw when researching said the oppiste

here one of the web sites (scroll towards the bottom)

http://www.bcae1.com/relays.htm

Thanks

Ben







The diagram on that site IS correct for NON-POLARIZED Relays! That is a relay that does not have a coil that requires it to be wired a specific way, either side can be either + or - on them. The relays I used had "polarized" coils and had to have the diode wired as I outlined above. Just as the ones you found also have polarized coils.



Again, the relays you are looking at have POLARIZED COILS, but they ALREADY have the diode installed for you, easier to use and set up for your use. Just make sure you keep the polarity + to + and - to - per the relays diagraming or you could damage the relay and the internal diode!


BOTH those relays you picked will work. If you notice the coil and the diode, each diode IS wired to as I explained above (again, I had used "polarized relays, but mine did not have a pre-installed diode as the ones you found).

On those you found + (non band) to + battery connection and - (band side) to the - battery connection side of the relay coil. The relays are just reveresed at their battery connection points and that is why you see the diode as being "reversed", it really isn't, it is wired exactly the same way in BOTH relays! Just the coil has been connected differently to the conection tabs, i.e. on one the + is on 85, - on 86, the other relay, 85 is - and the 86 is +. Other than that difference, it's basically the same relay. I'd guess one is wired for Negative ground vehicles, the other is wired for Postive ground vehicles. Again, either one will work in your application as it's not being plugged into a relay socket in an automobile, which, that would make a definite difference in which one you bought!

What a diode does in most circuits is allow current to pass through it in one direction only, that is if it is in a series circuit, + (non band side) is connected to the + side of a battery and the banded side (-) side of the diode is connected to one side of the relay coil (not across or to both sides of the coil), and the - side of the battery is connected to the other side of the coil, the relay would then energize and close to the N.O. contact. If the diode were put in the opposite way and the + side of the battery were to be connected to the - side (non band) end of the diode and the band end (+) side of the diode were conneted to one side of the relay coil and you connected the - side of the battery to the opposite relay coil contact, nothing would happen as the diode would have blocked the electrical current from getting through.

In this scenario on those relays you picked the diode is there to prevent the EMF kickback (EMF = Electr-Magnetic Field), which can give quite a kick as that website described, but the diode should be put in as I described above. If ONE IS NOT already included in the relay, which those you have picked are. And again, either one of those relays will work. Just make sure you connect and keep the polarity correct as shown on their diagrams.

As far as amps are concerned, that would depend on the load, with a fog machine, I'd go with a 20 amp relay at a minmum, those you picked are 30/50, so those are just fine for this use too.

So actually I was correct with my info for a polarity sensitive relay, but it does need to be the opposite way for a relay that is not polarized(as on that website you found - good find!). Those that have coils that do not have specific + and - connections. I didn't think about that at the time I typed my initial reply, that is I had used polarized coil relays, not the standard non-polarized type. My apologies for that oversight.
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ogamoga wrote:

But the one I picked is not polarized so I put it the way you said right.


Ben, if the relay is polarized, then the diode goes in as I described it in my first response, if the relay IS NOT polarized, then it goes in the opposite way, that is the non band (+) side of the diode will connect to the - side of the battety connection and the band end (-) side of the diode will be on the voltage (+) side of the battery connection. Just as in the website you had found. it is all explained on that website as well.

What would happen if you installed per my first instruction on a NON-Polarized relay is you would get a short circuit and the relay wouldn't work, even worst, it could damage the relay and possibly even the diode on such a relay.

This just happens to be one of those areas of electronics where it sometimes really confuses folks, even those of us that have been in it a long time (I've been in the fild over 35+ years) and we sometimes forget to add details that most folks with the knowlege would catch right off, as you did by researching it that I had negelcted to put in my initial reply that I had used polarized relays and had to install the diode as I had described.



But you or most novices would not have known that and that could have invited trouble, I'm glad you researched and caught that.



But, again, non polarized relay the diode goes across the coil (either direction is fine) as long as you connect the voltage (+) to the non banded side of the relay coil and again, ground or (-) to the banded (+) side of the diode. In essence this sort of makes the relay a "polarized" relay, but since the coil of the relay is not a true polarized coil, that is why the battery connections are reversed from what they would normally be on a dode across the coil. Hope that makes some sense.

BTW: if you can open the relay, you can actually solder the diode across the coil inside the housing, that's what I did with some of mine. Just have to be very careful when prying it apart you don't break the housing.

However some relays are permanently sealed, those you have to solder the diode to the coil contacts under the relay. I actually use and prefer relay sockets for those types when I can, and then just solder the diode to the coil terminals on the relay socket. This way, in case the relay ever wears out or goes bad, I can just snatch it out and change it and not have to worry about adding another diode. Just have to make sure on those that I don't install a polarized relay. But I know at a glance which are polarized and whic aren't because of where the + and - markings are I put on the socket and orientation of the diode in relation to those markings.

Good luck! And hope I didn't overload or confuse you even more with all this.
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Ok but in the realys I posted above I wouldn't have to deal with opening it up as it already has I doide in it...also I'm pretty sure those realys are polarized so I just then match positive to negative and negative to positive right? This is such a confusing topic

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ogamoga wrote:

Ok but in the realys I posted above I wouldn't have to deal with opening it up as it already has I doide in it...also I'm pretty sure those realys are polarized so I just then match positive to negative and negative to positive right? This is such a confusing topic


Ben, yes it is (a confusing topic!). And NO!, on a polarized relay with a diode pre-installed, IT IS ALWAYS + to + and - to -.

+ to - and - to + is/are for non-polarized relays that DO NOT contain a diode and must have one installed externally (or internally, when possible) to prevent the EMF feedback.



On the ones you have chosen, polarity MUST MATCH + to +, - to - or you could possibly damage your relay and/or the internal diode.
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ok but because I have a relay with a diode I dont need to put in another one and I just conect the positive wire to the connector that is conected to the positive end of the diode in inside right?

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ogamoga wrote:

ok but because I have a relay with a diode I dont need to put in another one and I just conect the positive wire to the connector that is conected to the positive end of the diode in inside right?




That is 100% Correct. When the diode is included already and the coil is polarized, it does make this a lot easier and (usually, but not always) less confusing to the end user.

It would only be different if the instruction sheet/diagram that came with the relay stated or had a note showing/stating otherwise.



The relays you picked out are positive to positive and negative(ground) to negative(ground) connections because they are polarized, have a definite + and - connection to them.
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ogamoga wrote:

And then because it has that diode installed then it will protect everything from any voltage spikes and stuff like that

yes, the internal diode will protect you from any EMF or voltage feedback through the relay coil.
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  • 2 weeks later...

Ok so I just got my relays and stuff in today and when I hooked everything up to lor and my computer it worked fine. However once I attached the fog machine and it started runing...it is causing the controller to rest....ie goes from solid to blinking and casue the program on my computer to freeze....help

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I think what is happening is that when the fog machine is running/turns on/or off it has an increase of voltage which is then sparking inside my relay to the controller resetting it. I believe the solution is a sunbber attached to the fog machines motor cicurit. However I have no idea how to do this, when to buy a sunbber, and if that will even work. Please help

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ogamoga wrote:

I think what is happening is that when the fog machine is running/turns on/or off it has an increase of voltage which is then sparking inside my relay to the controller resetting it. I believe the solution is a sunbber attached to the fog machines motor cicurit. However I have no idea how to do this, when to buy a sunbber, and if that will even work. Please help


Which relay are you using? Is it a 12VDC or a 110-120VAC coil? If 12VDC does it have an internal diode installed in it? Are you connecting it directly to a LOR dongle(channel) or using an adapter (Wall Wart)?

We need a bit more info as to how you installed it, how it's connected and type relay, power supply(ies) you have used to be able to help with a diagnosis or solution to the problem you're having.
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Ok it is all the information that I posted above but to reiderate...it is a 12v dc relay (which btw was intresting installing because I followed you instructions and the realy was not closeing so I had to turn it around and then it closed so I can now hear that click noise) and the realy is conected to my lor dc card being powered by a 12v dc wall wart. 12 amps. That relay is controlling a fog machine from a remote i took apart. I tested the voltage on the switch and I am mostly sure it is 120v AC and that make sence because you just plug the fog machine in to the wall. The relay does have an internal diode and I am preaty sure its the fog machine pump motor at falt because with the fog machine not connected everything works fine

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ogamoga wrote:

Ok it is all the information that I posted above but to reiderate...it is a 12v dc relay (which btw was intresting installing because I followed you instructions and the realy was not closeing so I had to turn it around and then it closed so I can now hear that click noise) and the realy is conected to my lor dc card being powered by a 12v dc wall wart. 12 amps. That relay is controlling a fog machine from a remote i took apart. I tested the voltage on the switch and I am mostly sure it is 120v AC and that make sence because you just plug the fog machine in to the wall. The relay does have an internal diode and I am preaty sure its the fog machine pump motor at falt because with the fog machine not connected everything works fine


The only thing I can think of is you may be getting inductance feedback from the motor. I'm not 100% sure of the value, but I think you may need a capacitor across the motors electrical connections. But I am not 100% sure of the installation of the capacitor, wether it would go across the motor leads or if it should be in series with the motor.

At a rough guess I'd try a .01Uf(microfarad) capacitor, but it could be a.05Uf or possibly even a .10Uf capacitor could work.

Hopefully there is someone here that may know the exact value of the capacitor you'd need, and the best way to install it.

As I am attempting to do this from memory, and it's been quite a few years since I've done any of this type of work.

I know there are some "electronics engineers" around the LOR forums, and they would be the ones best suited to tackle the installation of any extra components you may need to correct the issue you're having.

Sure wish my father was still alive, he'd know exactly how this would need to be wired, which would hopefully correct and fix the problem.
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Ok I don't know if this would make a diffrence but my fog machine is a ground forger and inside is the 120v pump also there is a little cicurt to convert the ac power from the outlet to dc 12 v to power a little fan? Would this conversion cicurit be a problem or is it most likely the motor

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