I dont want to use 120V switches because they are big, ugly, and expensive.

That’s simply not true. You’re thinking of wall switches, but anything you can find in the 12V world is also available in the 120V world, and more. You can find some very cool (even backlit) switches for AC use.

 

I got a nasty shock in my home shortly after I moved in because the amateur electrician previous owner screwed up an outlet.

Yeah, had the same thing. Plugged the computer into one outlet (wired backwards) and the printer into another outlet (wired correctly). When I went to plug the printer cable in, feeling the metal cabinet of the computer with the grounded printer cable, I got a full on 120 VAC across my fingers (one hand). Tore everything apart and couldn't find any mis-wired issues. Tore down the ceiling in the basement and found a wire that had been cut and spliced - black to white and white to black. Found many more violations and much worse. Lamp cord in the wall, flying taps in the ceiling with no access, seven or eight circuits tied together in a flying junction held together only with tape. Have to wonder why this house didn't burn down years ago.

 

That’s simply not true. You’re thinking of wall switches, but anything you can find in the 12V world is also available in the 120V world, and more. You can find some very cool (even backlit) switches for AC use.

I have bee purchasing and hoarding unique switches for years, and they are all low voltage. The completed control panel will be much more appreciated for aesthetics than function.

@wayneh my goal is always to find the simplest means to an end. practical. Not everybody shares my goal and that sometimes frustrates me. I'm learning to deal with it better, but I still get flustered when someone insists on reaching around the world to scratch their back with no reason cited. I was starting to get that way here, but at least here he has given a reason for his insistence on relays. It's pretty close to a rube goldberg device so I'll calm my horses and try to appreciate the "art" involved even though I don't understand it.

 

Having an earthquake right now. Monitor bouncing about. Not big, estimate 2.5 maybe.

[edit]
You can go to an auto wrecking yard and collect thousands of 12 volt relays. Many of them will be rated to handle 40 amps. Off hand I don't know what voltage they would be rated for (the contacts part, not the coil) but I'm confident 120 VAC could be managed quite safely.

A quick search of Mouser's site for 'automotive relays' shows 832 parts, of which six have contact ratings =>120VAC. Caveat emptor.

 

I was going to do a spoof post but as long as you mention it:

I have bee purchasing and hoarding unique switches for years, and they are all low voltage. The completed control panel will be much more appreciated for aesthetics than function. I will have switches on there that merely make fart noises, give the user an electric shock, and likely a ton more juvenile things. I will have slide switches operate as dimmers, key switches to release remotes, and I will even have the protected switch like you see on the trigger buttons for fighter jets. This will be a grown up's fidget spinner and just happen to automate my studio at the same time.

Then I looked at your original post with the image:


So I get to thinking and with home automation all the rage these days you may want to consider getting outrageous with something like this. Relay cards like this have become very inexpensive in combinations using 2, 4, 8, and 16 Channels. The relays in the link will handle 15 Amp 120 VAC loads and considering your loads that is likely more than adequate. Boards like this include software, the linked boards software looks a little like this. Actually rolling your own software is pretty easy. No shortage of ways to communicate with boards like this through a GUI (Graphical User Interface). Each of the 8 channels can also have a manual override so the user is not limited to using a PC. Eight mini switches could be easily configured to manually override the software.

I had to toss it out there. If you want to get geek or nerd in this project. Also, before I forget many of these boards have a GUI with timer functions so individual channels can be turned on remotely at preset times. You would be the envy of other geeks and star fleet commanders.

Ron

 

A quick search of Mouser's site for 'automotive relays' shows 832 parts, of which six have contact ratings =>120VAC. Caveat emptor.

OK. But of the 826 that didn't have a rating if 120 VAC, did any of them have a listed rating? Nevertheless, I stand willing to be schooled. If I have learned something today then let this be it - that most automotive relays are not rated for 120 VAC. Six are. But of the other 826, their rating is unknown. HOWEVER, I have a 30 amp automotive relay in my hand and it ONLY says it's 12 volt coil and 30 amp SPST contact. Says nothing of the voltage capacity of the contacts. Like I said, I'm willing to be schooled. But as yet, I don't see any evidence that supposes that any relay other than the six you found have any stated values on them. But hey! I'm willing to listen to solid proof.

[edit] I'll be out in the garage working on my marble machine.

 

OK. But of the 826 that didn't have a rating if 120 VAC, did any of them have a listed rating? Nevertheless, I stand willing to be schooled. If I have learned something today then let this be it - that most automotive relays are not rated for 120 VAC. Six are. But of the other 826, their rating is unknown. HOWEVER, I have a 30 amp automotive relay in my hand and it ONLY says it's 12 volt coil and 30 amp SPST contact. Says nothing of the voltage capacity of the contacts. Like I said, I'm willing to be schooled. But as yet, I don't see any evidence that supposes that any relay other than the six you found have any stated values on them. But hey! I'm willing to listen to solid proof.

[edit] I'll be out in the garage working on my marble machine.

I think the issue becomes that most automotive relays will either be switching 6, 12 or 24 VDC and used in a golf cart maybe 36 VDC. This is where it becomes nice to have a relay supported by a manufacturer's data sheet. Like you I have one laying here with a nice little mounting tab. The case reflects 12 Volt 30 Amp and that is about it. It does not even have the manufacturer so I will assume the Wong Chow relay garage in Beijing, China.

Ron

 

@wayneh my goal is always to find the simplest means to an end. practical. Not everybody shares my goal and that sometimes frustrates me. I'm learning to deal with it better, but I still get flustered when someone insists on reaching around the world to scratch their back with no reason cited. I was starting to get that way here, but at least here he has given a reason for his insistence on relays. It's pretty close to a rube goldberg device so I'll calm my horses and try to appreciate the "art" involved even though I don't understand it.

Thank you for sharing that. This truly is an adventure down Rube Goldberg lane. Nothing involved with this project is necessary. I just want to build it because I can. When no one is watching, I will probably attach a steering wheel and pretend I am flying the space shuttle or whatever. I am a nerd.

I was going to do a spoof post but as long as you mention it:

Then I looked at your original post with the image:
View attachment 137636

So I get to thinking and with home automation all the rage these days you may want to consider getting outrageous with something like this. Relay cards like this have become very inexpensive in combinations using 2, 4, 8, and 16 Channels. The relays in the link will handle 15 Amp 120 VAC loads and considering your loads that is likely more than adequate. Boards like this include software, the linked boards software looks a little like this. Actually rolling your own software is pretty easy. No shortage of ways to communicate with boards like this through a GUI (Graphical User Interface). Each of the 8 channels can also have a manual override so the user is not limited to using a PC. Eight mini switches could be easily configured to manually override the software.

I had to toss it out there. If you want to get geek or nerd in this project. Also, before I forget many of these boards have a GUI with timer functions so individual channels can be turned on remotely at preset times. You would be the envy of other geeks and star fleet commanders.

Ron

That is exactly where I am heading with this project. I already have the Arduinos, and I am going to SF Supply in about an hour to talk about parts needed to build my own relay board like the one you linked. That was the goal all along, but I knew I had to get the basics down frist.

I think the issue becomes that most automotive relays will either be switching 6, 12 or 24 VDC and used in a golf cart maybe 36 VDC. This is where it becomes nice to have a relay supported by a manufacturer's data sheet. Like you I have one laying here with a nice little mounting tab. The case reflects 12 Volt 30 Amp and that is about it. It does not even have the manufacturer so I will assume the Wong Chow relay garage in Beijing, China.

Ron

HA!!! He said "Wong Chow"!!! LOLOL!!!

 

Let us know what you come up with. Rather than an Arduino, which I like, the Rasberry Pi may be a better solution but see what they have to share with you.

Ron

 

Like you I have one laying here with a nice little mounting tab. The case reflects 12 Volt 30 Amp and that is about it.

Yeah, I have that one too. 12 V 30 A is all it says. Four terminals.

Got one laying around here with a capacitor and resistor built in. Has a double coil I think. Came out of my wife's crashed Toyota Celica. I think it had something to do with the fuel pump, but I can't seem to get it to do anything spectacular.

I will probably attach a steering wheel and pretend I am flying the space shuttle or whatever. I am a nerd.

The space shuttle was flown with a stick.

 

Yeah, I have that one too. 12 V 30 A is all it says. Four terminals.

Got one laying around here with a capacitor and resistor built in. Has a double coil I think. Came out of my wife's crashed Toyota Celica. I think it had something to do with the fuel pump, but I can't seem to get it to do anything spectacular.

That circuit opening relay goes for $130. Don't throw it away. Don't believe me? Google the part #. They're unobtanium.

 

That circuit opening relay goes for $130. Don't throw it away. Don't believe me? Google the part #. They're unobtanium.

That would be a keeper!

Ron

 

I think the issue becomes that most automotive relays will either be switching 6, 12 or 24 VDC and used in a golf cart maybe 36 VDC. This is where it becomes nice to have a relay supported by a manufacturer's data sheet. Like you I have one laying here with a nice little mounting tab. The case reflects 12 Volt 30 Amp and that is about it. It does not even have the manufacturer so I will assume the Wong Chow relay garage in Beijing, China.

Ron

This is a very important point. When scrounging, it's common to get stuff that it is impossible to find a data sheet for. It's one thing when you use it for a demonstration type project using low voltage. It's a whole different thing if you are using it for something with life-safety implications. The insurance adjuster will be taking a very close look...

And Wong Chow Relay LTD probably lied about the 30A rating anyway. The expedience is strong in that one.

 

Let us know what you come up with. Rather than an Arduino, which I like, the Rasberry Pi may be a better solution but see what they have to share with you.

Ron

I am actually considering some of the knock-off brands..Why not? they all use the same parts

 

Your not going to want any relay boards with a bunch of relays use low voltage and put the relay in the outlet box way better then running a bunch or 12/2 to your control box. I've done a bunch of remote control outlets the 120 outlets 120 push buttons looked nice worked great small conduit to the box you'd have a big conduit plus add to the load switch 50 feet away is like adding a 100 foot loop you'll get dimming and all kinds of funny things happening new vacuum cleaner every month. Stuff like that.

 

I am actually considering some of the knock-off brands..Why not? they all use the same parts

You can use an Off brand or knock off. Before I retired anything I did programming with was done for a PC, that is what they wanted. Things like Arduino I have played around with at home I simply bought the brand name stuff because it was there and if something didn't work I could get an easy exchange. Incidentally I am not and was not a programming type but I did hire some very good ones. If I had to rely on my programming skills I would have starved to death. Anyway when it comes down to the gizmo (technical term) just try and select what will work best for your planned application.

Ron

 

Your not going to want any relay boards with a bunch of relays use low voltage and put the relay in the outlet box way better then running a bunch or 12/2 to your control box. I've done a bunch of remote control outlets the 120 outlets 120 push buttons looked nice worked great small conduit to the box you'd have a big conduit plus add to the load switch 50 feet away is like adding a 100 foot loop you'll get dimming and all kinds of funny things happening new vacuum cleaner every month. Stuff like that.

I am using low voltage PCB relays...12V

 

I am actually considering some of the knock-off brands..Why not? they all use the same parts

If you are talking about Arduinos, pretty much anything works though most of the Chinese knockoffs are using the ch340 instead of the FT232 USB chip. A knockoff nano costs like $5 quantity 1 (I bought 5 for $15 off ebay, US ship). I love the nanos because they are breadboard friendly and the same as the Uno from the programming perspective. Easy to make a PCB for them and doesn't require that weird shield shape.

 

The ones I posted you can get for nothing and there made for stuff like this
I got 100 of them for 50 cents each buying in bulk.