I have what I think is a simple circuit design question, and I think I have a solution, but I’d like advise about something better, or even an off the shelf product that will solve my problem.
Goal: In my garage I would like two lights that change state based on the status of the garage door.
Door closed: All lights off
Door completely open: Green light is on
Door between the open and closed position: Red light is on
Proposed solution: Use some momentary switches and lamp cord to power some 110 volt standard light bulbs hanging from the ceiling.
Green light circuit: A momentary on switch (when pressed, the circuit is completed) installed to be pressed by the door in the completely open position. The green light is on only when the door is completely open.
Red light circuit: Two momentary off switches (when pressed, the circuit is broken) with one installed to be pressed when the door is completely open, and the other pressed when the door is completely closed. This way the circuit is complete (and the red light on) only when the door is neither completely closed nor completely open.
The main advantage of that setup is that 110 volt momentary switches are easy to find and cheap. Light sockets, colored 110 volt bulbs, and lamp cord are also cheap and easy to work with. The primary disadvantage is working out mounting positions for the switches so that they are pressed at just the right time, without being smashed or interfering with the working of the door.
Another option is to do something with reed switches/door sensors. The main problem is that I’m not finding 110 volt reed switches. The main advantage is that the reed switches should be easier to install than the momentary switches, because physical contact isn’t required. This seems more complex. I could probably solve it with an arduino or similar, but that seems like overkill for just wanting a simple stop/go light.
For safety and more options, I’d avoid 110V and go with 12-24 volts. [del]Your[/del] my garage door opener is already sending 24VAC to the safety eye. Ethernet and phone cable can handle the lower voltage if need be. Or bell wire. Grab an unused phone charger or any other wall wart of whatever voltage you want. Old laptop, camcorder, and printer power units have a decent wattage rating. 12V lets you access automotive lighting options. A trailer light kit will get you red and probably yellow/orange. For switching? Go industrial in your searches. These run up to 250VAC and don’t leak voltage.
ETA: ninja’d on the link.
Outdoor landscape lighting is also low voltage if you run across someone tired of theirs.
Chain drive, screw, whole door pivots? When I needed to install lights like these at work, We’d run limit switches that made off the door itself. Actually we added ell brackets to trip them.
Yes, do this.
In most places in the US, #18 lamp cord is not allowed by the electrical code. (And probably invalidates your house insurance.) Ungrounded, uncabled #18 wire (‘lamp cord’) is not allowed for permanent wiring; only temporary, movable items (like ‘lamps’).
It’s an odd install. It is a screw drive opener that is mounted vertically in between two doors. A large bracket connects the opener to both doors. As I’ve had to tell the guys who came out to replace the springs, and commented on the odd setup, “it was like that when I found it.” Replacement with fiberglass or steel doors and jackshaft lifters is $3-5k, so I’m not doing it until something permanently breaks.
There is already a limit switch to stop the screw from turning when the door reaches the top. I could install another limit switch to activate the green light, but that is not near where I actually want the light, so it will take lots of wires.
Arduino is a very cheap and simple microprocessor kit. I don’t see how it can be “overkill” for any purpose. I’ve got one controlling the lights on my bicycle.
I wouldn’t use lamp cord for a permanent install. This would be a true lamp installation. What I would probably do is use a hanging light setup, just a cord with a light socket on the end, and replace the rotating switch with a momentary switch. Somebody was good enough to install ceiling mounted electrical outlets positioned for separate openers, or a single, center mounted opener. However, they didn’t bother to see that due to a support beam, there isn’t actually any place to put ceiling mounted openers.
So anyway, this would be a light plugged into one of the unused ceiling mounted outlet, and hanging down so it is visible. The lamp cord is just because it’s often easier to make a hanging light from a plug, cord, and receptacle that to buy a premade one of the wrong length.
OK, this is probably what I meant to ask the first time. If I do use a low voltage circuit, then reed switches are probably the way to go, because then I just need to put a magnet on the door.
Is there such a thing as a reed switch that turns off in response to a magnet? Otherwise how would I wire the red light so it is on when the circuit is broken at both ends, but off when the circuit is completed at either end?
I could do that with an arduino because I know how to program
if (! DoorOpen and ! DoorClosed) then Red=on
, but it seems like that should also be possible to do in a discrete circuit, I just don’t know how.
You have a bit for door-open, a bit for door-closed, then you appear to have 3 possible output states.
So the table is:
DO DC | Out
0 0 | Red
0 1 | Off
1 0 | Green
1 1 | ???
You now need discrete logic gates. You can either pick gates from a catalog or you can tell me what gates you have and we can work out a solution. For example, 3 NAND gates and 2 NOT gates would solve this table. (the D0 & DC) case you have not defined so I am ignoring it.
For example, DO NAND DC = Red, DO NAND (NOT DC) = Off, (NOT DO) NAND DO = Green.
These discrete logic outputs have very little drive strength, so I recommend you use SSRs, which are about $10 each on Amazon, to actually drive each circuit. Unless you are doing small LEDs, then you can probably do it with the output of the discrete logic directly with an appropriate resistor inline.
Mouser charges $8 shipping, and you will need a perf board and a soldering iron to build this circuit. (prototype on breadboard and then I recommend you solder to perf board to make it more rugged). You will also need a 5V power supply, basically all the discrete logic you can buy uses either 3.3 or 5 V.
Or you can use an Arduino. There are very cheap clone ones on Amazon that are compatible with the IDE.
I think 1 1 has to be “lp0 on fire” or equivalent.
Thanks, that was very helpful. And it reminded me, I think there is actually an Arduino in the basement I can use. I found shields and other parts for one, but not the actual controller. That’s a thread for MPSIMS, though.
The SSRs are a great idea. That’s the thing, I often don’t know the name of what I’m looking for, so I can’t find it. I discovered there are normally open/closed reed circuits. So I can have a switch that is closed when the door is open, and a switch that is closed when the door is closed. It is mostly confusing because for reed switches, often used as door sensors, the terms open/closed refer to both the state of the door and the state of the circuit.
Anyway, combining three reed switches with two SSRs will let me control two lights, without having to use logic circuits or an Arduino. I still plan to use regular 110 volt light bulbs, and let the SSRs switch them. Colored LED lightbulbs are $6, and I can use them with lamp parts sold in the next aisle.
What is the best way to connect a single low voltage power supply to the three reed switches? Is there something more elegant than just putting them all together with wire nuts?
Will it make anybody’s head explode if I use something like 14/3 wire as my lamp cord? Then I can use the red wire as hot for the red light, the black wire as hot for the green light, white as common neutral, and ignore ground. (I could do 14/2 and use ground as common neutral, but that seems real bad.)
The traditional way to do this is a circuit board. The classic breadboard, which you can get in a perfboard form so you can solder down the connections, has a strip for power and a strip for ground.
14/3 is fine. Two separate 120 hot circuits on black and red is a completely normal application. Note that you are not allowed by electrical code to have connections outside boxes. You would need to have the 14/3 come from a box that has the SSRs and electronics in it (don’t forget a bushing to protect the wire where it comes out of the box!), and goes to a box that has one of the bulbs attached in a receptacle to it.
Also note that you can get tons of nice bright light with modern low voltage LED solutions, such as neopixel, and you get to have all your colors from the same LEDs.
The neopixel version of this solution would be far, far simpler and cheaper.
For example, you just connect 3 wires from this ring to 3 terminals on your arduino, plug a wall wart that gives you 5V in somewhere, and power the switches using your arduino also. I would use a perfboard shield so the wires are held down by solder. You supply the power to the light ring and the switches from the +5 out on the arduino.
Then, your 3 (or 4) output states are just a handful of lines of code in your arduino. You can write this after you spend the 20 minutes it takes to get a NeoPixel example working.
I am quite amused by the obvious solution here. Screw that messy hardware, just build your whole device in software in 15 minutes and spend the rest of the time relaxing! You don’t have time to wire up 2 boxes powering 2 light bulbs with 2 solid state relays handling 120 volts and 3 total protective metal boxes, do you! Ain’t nobody got time for that. Just grab an arduino, a UL listed power brick for it, a perfboard shield (buy or make one), a neopixel ring, and some doorbell wire from the hardware store. And your 2 switches.
What problem are you trying to solve? Or is it a “just because I can” project? My visual clues as far as garage doors are, is it moving or not? If so what way? If not does it appear within the frame and if so how much.
BTW, if the motor runs off a reversing motor starter/relay, there may be an unused contact on each to drive the red light. In the reed switch method if you stop the door partially, say for a little ventilation but not fully open, your red light is always on.
Here’s the simplest circuit for the OP’s purpose. The switch on the left is the door closed (idle) position target, and is a normally closed-held open switch (or NCHO)…think refrigerator light. All lights are off in this state. When the “door move” command is activated, this switch closes sending power to the second (single pole-double throw, or SPDT) switch, and the red (door moving) light is on. At the door full-open target position, this SPDT switch changes states and the green light comes on. Reverse (close) the door, and the green goes off, the red comes on while the door is moving, then goes off when the door is home (closed).
Hot-----O__O------O__O-----*----( red light)----Neutral (or -)
{Tildes(~) on second line are place carriers for the "graphic", not part of the drawing.}
Choose the power supply and type of lights that suit your fancy... eitherwhichway, you'll need (at least) a minimum of two switches and two lights... I'd prefer to not over complicate things with the addition of microprocessors.
Second to the SPDT or DPDT switches (one when it is open and one when it is closed). You can hardwire the logic into the circuit fairly easily, as has been stated elsewhere.
You cannot use reed switches. The will not handle significant current or voltage. They are intended for alarm system inputs, which range from about 4 VDC to 8 VDC at less than 10 mA. The contacts will fuse and then heat up rapidly. You can’t even use them for powering a coil on a low-voltage relay.
Personally, I’d combine several suggestions and use a 12 VDC wall wart for the sensing circuit and devices, then use that to activate two contactors (12 VDC coil and 120 VAC rated contacts). Wire the contactor outputs to standard receptacles so you can plug in your drop light(s). This would be inherently safe for you…as long as you know what you’re doing with the contactors and receptacles.
Two SPDT spring switches. Switch 1 is for door closed. Switch 2 is for door open. Wire 12 VDC to common of switch 2. When switch 2 is activated (door closed), the voltage goes nowhere…no output. When door begins to open, switch 2 sends 12 VDC to common of switch 1. Switch 1 has two positions (throws). One is for the red light (door in motion) and one is for the green light (door open). When the door is fully open, switch 1 changes the output from red to green. Take the red light and green light outputs to the coils of two contactors. Wire 120 VAC through the contactors, one for red and one for green, and power two receptacles. Plug whatever drop cords you want into the receptacles. You can get contactors at electrical supply stores, some hardware stores, and even on-line.
You can do all the wiring to the switches with 22 AWG multiconductor.
Yes, exactly if the door is only partially open, then the red light is on. The problem I’m trying to solve is to have a visual indicator that the door is only partially open when the door is, for example, above the rear window of the car, but not completely open.