I am working on a project for my daughter that involves using a nano to control the lighting in a dollhouse. I went with the nano because that's what I had laying around and ease of powering with a USB adapter. Anyway - i'm stummped.
This dollhouse chandelier came prewired with 3 leds, a switch and a 3v coincell battery. This was asealed unit, so once the battery dies, you are screwed. I was able to grind the top off, remove the battery and solder leads to it.
Here is my problem:
To start with I have no idea of the forward voltage or anything dealing with the leds. all I know is there are 3, they are wired together and were powered by a 3v coincell battery.
If I connect the leads directly to the 5v and ground, the LEDs light - but are very bright.
When I try a current limiting resister, nothing works. Have tried, 220, 470, 1k and 10k on a whim.
I also tried using a voltage divider with 1k and 2k resister off the 5v lead to get 3.3v and still the LEDs wont light up.
It obviously works on 5, but it's way too bright.
any ideas? I know I am overlooking something
thank you
need wire diagram and/or photos
hello - thanks for the reply.
here is a pic of the chandelier and the nano.
literally just using the nano for a power source. (i know it is overkill but i had a bunch laying around that were given to me.)
Right now just using the 5v and GND pins
Please re-shoot and show the entire PCB and all connections. Also please draw a wiring diagram, shoot that and post it.
When you do, reference the connections to the chandelier because it is not easy to make out in the photo.
That is a distinct possibility. Or the Nano. Coin cells have an inherent current limiting resistor - the high internal resistance.
Isn't red usually positive and black negative? You have red going to ground.
yes - i used wrong color leads
You mean you attached them yourself? If so, in future, mention things like that so we don't go nuts finding things you already know.
the chandelier only has 1 wire - red in the picture. The ground is on the case. Hard to see but the black wire is physically attached to the housing (it scews down and i have it soldered in there)
I would cut the problem in half, myself. Test the lamp and Nano separately.
We still have no diagram from you, so can't guess why the current limiting circuit you made didn't work...
With beginners, both the design and implementation have to be examined.
here is the voltage divider circuit i tried.
I measure 3.3v on it. But it will not light the chandelier.
If I take the chandelier leads and connect to 5V and GND (pin 27 and 4) , it lights, so I know my LEDs and solder connctions are good.
Forget the voltage divider. It's a mistake. Please don't apply 5V to the LED again. If you didn't burn it before, you will eventually that way. Try a current limiting resistor. Post a diagram first.
this is how i have been connecting it, and i have tried 220, 470, 1k and 10k resister.
No matter what I use, it wont light.
also - wanted to add that the other LED (the one w/ the limiting resister attached) works fine. When the chandelier does not light, the other LED is still on, so I am thinking that would rule out a short on the 5v line?
I have to ask: why use a nano at all? What is the "project" ie, why do you think an Arduino is needed at all? Did I miss the sensor input you are trying to use? Or is this just to use a cell phone battery pack in place of the dead coin cell or something like that?
hi - i am using the nano for ease of power options (USB battery pack i already had) and becuase I have some on hand that were not being used, etc. I was going to try to make the chandelier look creepy and have it maybe randomly change brightness with PWM or something, but first things first I am just trying to get it to light up. The "project" is a haunted doll house for my daughter, so there may be other inputs down the road.
yes they are 1/4 watt. all i have currently
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First thing here is to check that you haven't damaged the LEDs by supplying them with 5V. If the original button cell is still ok, try that. If not, try two dry cells like a couple of AAs in series. If the chandelier doesn't light, you may have damaged the LEDs.
If they do light up, measure the current and work out what series resistance you'll need. For example, if the current is 20mA, then a drop of 2V will need 2/0.02 or 100 ohm.
Be careful however, and watch what current the Arduino can supply.
Any way you can get at each of the leds individually? There will be separate wires going to each one, right? I understand you don't want to destroy the plastic chandelier but if you could it would make your eventual project a lot easier. That way too, you could even rewire the thing entirely using leds of known forward voltage so you can get the resistor values exact and make dimming and other effects a snap.
