Aaron Maue Posted January 30, 2012 Share Posted January 30, 2012 I'm building a prop for next year's show and was hoping there might be an easier way to do what I'm planning...To make a long story short, what I'm looking for is a way to input 2 standard 110VAC lines into a device and if either input (or both inputs) is turned on, then, it turns on another 110VAC device.I could achieve this effect with another channel of LOR output, but right now, have a self-contained 16-channel prop and don't want to run a 17th LOR channel to it from another controller. I've come up with a way to do a logic OR of two of the 16 channels to drive a 17th "channel", if you will. And I've figured out a way to use two relays to achieve the effect. What I'm wondering if there's such a device that exists that would do it in a single device, as I think it would make the wiring much simpler.I've done a couple hours of hunting and haven't discovered it yet, so thought I'd put it out to you good folks to see if you'd heard of / used such a thing. I'm wondering if a DPST relay is what I'm looking for, but can't seem to find one for 110VAC applications.Thanks in advance for any help! Link to comment Share on other sites More sharing options...
k6ccc Posted January 30, 2012 Share Posted January 30, 2012 Yes there are some fancy ways to do it, but the easy way is to have each of the controlling circuits control whatever it is they are controlling and also a 120V SPST relay with normally open contacts. Wire the circuit for your 17th circuit so that an unswitched hot is connected to one contact of each relay, and the other contact of the relays connects to your 17th load. That way if either relay is energized, your 17th circuit will be energized.I will draw a schematic for you when I'm on a computer (a little tough from my android). As for the relays, even Radio Shack should have something usable (although that is not where I would). Link to comment Share on other sites More sharing options...
Aaron Maue Posted January 30, 2012 Author Share Posted January 30, 2012 k6ccc wrote: I will draw a schematic for you when I'm on a computer (a little tough from my android). As for the relays, even Radio Shack should have something usable (although that is not where I would).Jim,That would be much appreciated. I've got a drawing sketched out on some scratch paper at my desk, but the part of the circuit with the load attached to it just doesn't look right, so I'm sure I've got something wrong. Link to comment Share on other sites More sharing options...
Scott Cockroft Posted January 30, 2012 Share Posted January 30, 2012 It can be done with one SPDT(single pole double throw) relay if both inputs share the same neutral. You will not be able to do any dimming or special effects on the second input since the relay will need to be either on or off.Relay connections:“common” to the 17th load hot“normally closed” to input 1 hot“normally open” to input 2 hotone side of coil to input 2 hotother side of coil to neutralWhen power is applied to input one it will pass through the relay contacts to the load. When power is applied to input 2 the relay coil will be powered and pull in the contact and pass input 2 power to the load. If power is applied to both inputs the relay coil will be energized and the load will be connected to output 2. Link to comment Share on other sites More sharing options...
Aaron Maue Posted January 30, 2012 Author Share Posted January 30, 2012 Scott Cockroft wrote: It can be done with one SPDT(single pole double throw) relay if both inputs share the same neutral. You will not be able to do any dimming or special effects on the second input since the relay will need to be either on or off.Relay connections:“common” to the 17th load hot“normally closed” to input 1 hot“normally open” to input 2 hotone side of coil to input 2 hotother side of coil to neutralWhen power is applied to input one it will pass through the relay contacts to the load. When power is applied to input 2 the relay coil will be powered and pull in the contact and pass input 2 power to the load. If power is applied to both inputs the relay coil will be energized and the load will be connected to output 2.Scott,Since input 1 and input 2 are technically 2 different circuits on the same controller, will the neutrals actually be the same? The entire LOR controller is powered from the same outlet on my house, so it seems as though the neutrals would be identical. Is that, indeed, the case? Link to comment Share on other sites More sharing options...
Scott Cockroft Posted January 30, 2012 Share Posted January 30, 2012 Yes, if they are powered from the same outlet they would be the same.Where you could have a problem is if you have a controller with two input power cords and they were connected to different GFCI receptacles on your house. Even then it woukld be okay if both channels were either in the first eight channels or they were both in the last eight channels.You could also use a DPDT (double pole double throw) relay and switch the hot on one set of the relay contacts and switch the neutrals on the other set of contacts. Link to comment Share on other sites More sharing options...
Aaron Maue Posted January 30, 2012 Author Share Posted January 30, 2012 Scott Cockroft wrote: You could also use a DPDT (double pole double throw) relay and switch the hot on one set of the relay contacts and switch the neutrals on the other set of contacts.This looks to be ideal for my particular setup. I'm assuming I'd still tie one side of the coil to input 2 hot and the other side of the coil to neutral, right? Link to comment Share on other sites More sharing options...
Scott Cockroft Posted January 30, 2012 Share Posted January 30, 2012 Aaron Maue wrote:Scott Cockroft wrote: You could also use a DPDT (double pole double throw) relay and switch the hot on one set of the relay contacts and switch the neutrals on the other set of contacts.This looks to be ideal for my particular setup. I'm assuming I'd still tie one side of the coil to input 2 hot and the other side of the coil to neutral, right?Yes, that's correct. Link to comment Share on other sites More sharing options...
-klb- Posted January 30, 2012 Share Posted January 30, 2012 If your goal is to simplify wiring, complexity, and troubleshooting, I actually think two separate relays, each with a coil to one of the two channels, and in parallel switching hot on the extra load will be the simplest. Link to comment Share on other sites More sharing options...
rwertz Posted January 30, 2012 Share Posted January 30, 2012 Like Kevin, I would still use two relays. But Scott's single relay idea was fantastic Link to comment Share on other sites More sharing options...
Aaron Maue Posted January 31, 2012 Author Share Posted January 31, 2012 OK, so against the recommendation of a couple of you, I decided that Scott's suggestion was just too slick not to give it a shot. So, I went the DPDT route and it worked beautifully. Being an engineer by degree, I regularly choose the trickier route for no particularly good reason. My wife loves this about me. Many thanks to everyone who provided advice. This community is the best. Link to comment Share on other sites More sharing options...
Paul C Posted February 1, 2012 Share Posted February 1, 2012 You should put a diode in parallel with the coils of your relays. When the output goes false, the collapsing field/coil will induce a voltage back to the controller. Link to comment Share on other sites More sharing options...
Aaron Maue Posted February 1, 2012 Author Share Posted February 1, 2012 With the DPDT relay, I just have one coil to worry about. Can I assume I still have the need to put a diode in parallel with the coil? Hate to ruin my very spendy controller. And just to be sure I understand correctly, since the coil is between pins 7 & 8, I would need to put the diode across those pins, right? Finally, do I need to worry about the direction of the diode?Thanks. Link to comment Share on other sites More sharing options...
rwertz Posted February 1, 2012 Share Posted February 1, 2012 Can you even put clamping diodes on an AC coil? Link to comment Share on other sites More sharing options...
rwertz Posted February 1, 2012 Share Posted February 1, 2012 Maybe a varistor? Link to comment Share on other sites More sharing options...
plasmadrive Posted February 2, 2012 Share Posted February 2, 2012 NOT A DIODE! Unless of course you are studying secret smoke :?Use an RC snubber if you think you must.. but with small relays like that (assuming you are using a fairly small relay), it is really not much of an issue unless you are driving the coil with a small low PIV triac. Link to comment Share on other sites More sharing options...
Aaron Maue Posted February 2, 2012 Author Share Posted February 2, 2012 I prefer to keep all of the magic smoke INSIDE my electronics. I'm using a small relay with the coil driven by one of the channels on the CTB16D. Sounds like I'll be OK. Link to comment Share on other sites More sharing options...
Scott Cockroft Posted February 2, 2012 Share Posted February 2, 2012 Aaron Maue wrote:I prefer to keep all of the magic smoke INSIDE my electronics. I'm using a small relay with the coil driven by one of the channels on the CTB16D. Sounds like I'll be OK.You will be ok. I use a lot of relays for channel doubling. I don’t have any diodes or varisters on any of the ones I use. Just make sure the channel that drives the relay coil is either on or off and doesn’t have any dimming or other effects. Link to comment Share on other sites More sharing options...
Aaron Maue Posted February 2, 2012 Author Share Posted February 2, 2012 No dimming planned. Just on/off.Thanks to everyone for all your help. Your generosity of thought/time is much appreciated.I've got a couple weeks of work left to complete the prop that's taking advantage of the results of this thread. I'll be sure to post results/documentation/etc. for the whole prop, in case someone cares to use it. Link to comment Share on other sites More sharing options...
Alan C Posted February 2, 2012 Share Posted February 2, 2012 Paul C wrote:You should put a diode in parallel with the coils of your relays. . . As others have said, DO NOT ATTEMPT THIS WITH AC! You will find it will work well for 0.017 seconds, then the diode will short out the channel, damaging the triac on the controller!Regards,Alan C. Link to comment Share on other sites More sharing options...
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