Before you read I'm really low budget so I can't go out and buy anything... just got some wires and electrical tape.

I'm working on a project and I've come into some problems while wiring.

I have two 9 volts hooked up to make 18v, which leads to a switch, and the switch leads to sensor, which if on, sends power to a motor.
This system is working fine, and there have been no problems.

I need to add a light into the system, and it has to work the same as the motor: If the switch and sensor are on it receives power. However this specific light burns out on my current 18v system. (works on my 9v prototype) I can't replace the light because no others will fit in the oddly specific location i've crammed it into. I can't lower the system to 9v because the motor will be much too slow. And I can't add a duplicate system because I only have one switch and sensor.

What do I do?

 

Is the light and LED or does it have a filament?
If it has a filament what current rating is it?
Is one end of the motor connected direct to the battery or switch? If so, which?

 

Can you describe "the light" in more detail? Voltage rating, current drawn, type (LED, CFL, Incandescent,...)

 

The light is an old christmas light: (I believe it is LED)

The the negative wire of the battery goes to a switch. That switch has one wire leading off that connects to switch number two. Switch number two's wire connects to the negative of the motor. The positive on the motor connects directly to the positive on the battery.
Hope that helped!

 

Nope, your description would be better with a wiring diagram...

Use a white led with resistor.

 

Is there any other way? 1 because I am broke and two because I'm still messing around with the voltage, so I might need to increase the voltage on the motor but keep the light at 9

 

alright then where would I find something like that?

 

Did you take the light from an old Christmas light string? If you're in the US, I'd guess it's from a 100 light string that was wired as two series 50 light strings.

And I'd also guess, from extremely zooming in, that the bulbs are incandescent.

That would make each lamp about 2V. Which doesn't make sense because, although its supported by your description, it suggests that 9V would have also burnt them out.

We need the information requested by the other members.

 

Heres a picture of the exact lights I'm using:

They came from a 100 or 50 bulb line.
Here is them powered by a 9 volt:


And here is a quick drawing of the system atm

 

If you were to plug in the set with that one bulb disconnected, do any bulbs light up? If so, can you count or estimate how many? Also, whether is is a 50 or 100 light set is important.

You could put the bulb in parallel with the motor, connecting one side to the switched power line and the other to the junction point between the two batteries. However, this will affect the battery lifetime.

It may not be an issue depending on how long this will operate. The batteries may only operate for less than 10 hours. Can't be sure without knowing the current drawn by the motor and light.

 

a lot of the lights have one or two broken connections, as I've never really needed more than one or two. The power outlet is gone to who knows where and I can't find a complete set of more than 3 bulbs. However if you are testing its parallel, then I can say that each bulb has a positive, negative, and some third wire that I believe makes it a parallel circuit. And we used to put these on the christmas tree and I remember being able to pull out the bulbs and have the others still light. I've been looking up stuff to try to find this specific light, and I believe I have found it. Its called an LED M5 christmas light. Its a roll of 50. https://www.christmasdesigners.com/much-electricity-led-christmas-lights-use/ Talks about wattage per bulb and the whole strand if that is what you are looking for. Sorry I couldn't be of much help but I hope the link helps you.

 

Are you using three bulbs for your light?

The link is for LED lights. These are incandescent. From your description, I am making two observations. One, they come from a 100 string light. They are wired as two 50 light strings. The third wire brings power to the second string. Two, the voltage required by the lamps is about 2.5 volts. If you are using three, that's 7.5 volts. Close enough to 9V. I would expect that 9V across a 2.5V lamp would blow it. But I don't know the voltage RANGE these bulbs can take.

They are blowing out when connected as you drew, because the current drawn by the motor in series is too much for the little bulb. The bulb is acting as a too small fuse.

Note I said series. In parallel circuits, current divides down each path, depending on the load in each branch.

I mentioned one way, but we need to confirm its effect on the batteries. I can't remember...

Can you add a third battery source for the light? It could be two AA cells if they light the lamp.

I am on my phone. I'll draw a quick schematic in a few...

 

I might be able to add some room but space is very limited. Besides I need the light to only work when the two switches are on and I don't have any duplicates or places to but them anyway as they are operated by a very small lever buried deep within the other internals.
and no I am only using one bulb which is already isolated to two wires. Its very interesting that you say they should work at about 2.5 volts. The 9volt definitely works, (I left it on all night to see if it would blow out after an extended period of time)

And If you look at the "Cronial or M5" part, as the lights are M5, to the left it says "LED mini lights"

 

Yeah, but I am positive from your pictures that page is incorrect. If you zoom into the light on your posted picture, you can see the two wires that hold the filament. They aren't LEDs,



Here's the simple wiring that I am thinking about. Remember, I am not sure what this will do to your batteries in the long run.



And if you can use a separate battery for the light, try this.


(Oops, I just noticed something, Ignore the + sign on the motor. I have inserted it backwards.)

 

Ya know... that might just work. Im gonna make a prototype and I'll see if it will work. And if your nervous about the battery's lifespan, I've designed the batteries to be easily removable, and I have way too many 9 volts.

I'll let you know if it works

 

Hey I dont know what Is wrong with my prototype. Instead of being off when the switches are off, the motor is slow and the light is dim then when the switches are on the motor speeds up and the light gets bright. Almost as if until it is only using one battery until the switches turn on. I need the switches to turn on and off both the motor and the light. Here is a picture.


The one unmade connection in the bottom right is my simulated switch as i have none available atm

 

The rug makes it hard to see your connections. Not to mention that the picture is way out of focus. And I think I see only one switch. Is the yellow thing on the left a motor? And the yellow thing on the right is a switch?

Can you set it up on a plain background and try to get s picture in focus?

 

lol sorry I'll take another picture

 

There ya go

 

Some of those sorts of lights are designed to short when the filament opens.