Instructables
Ok get your mind out of the gutter. I am talking about the beautiful blue glass bottle that the Bawls soft drink comes in. I tried one the other day and thought the glass bottle could be used for something interesting. At first I was just going to stick an LED into it, but I wanted something a bit more interesting. So I threw together a quick and dirty circuit that uses a photo-cell to turn on a transistor which powers an LED. The parts should cost only 2 or 3 dollars, and are available almost anywhere.

Click here to see more PICTURES and a VIDEO of the Blue Bawls LED light
Here is a new schematic that allows for a On/Off/Auto switch
 
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Step 1: Gather the parts

Picture of Gather the parts

Step 2: Breadboard the circuit (if you want to test it)

Construct the circuit according to the schematic shown on the previous step.

Note: Depending on the photo-cell used the 100K resistor value might need to be changed. A pot could be used to determine the optimal resistor value.

Step 3: Solder it together

The cap is used to hold the light in position. All of the parts will be connected to the cap. Three holes will have to be drilled in the top of the cap. Then solder the parts together according to the schematic shown on the previous step.

Step 4: Detailed Cap Construction - Prep. the Cap

There are two holes that are needed in the cap. One for the power and a second for the photo-cell. Since the photo-cell is large I simply drilled two holes side by side.

Step 5: Detailed Cap Construction - Solder Method Step 1

Trim both resistors to the length shown (it doesn't matter what end of the resistors are used). Solder both resistors to the red battery snap wire (positive).

The resistor values are represented by color bars, look here for pictires:
[http://alan-parekh.vstore.ca/product_info.php/cPath/12_13/products_id/52" target="_blank" 100K ohms Resistor]
[http://alan-parekh.vstore.ca/product_info.php/cPath/12_13/products_id/40" target="_blank" 470 ohms Resistor]

Step 7: Detailed Cap Construction - Solder Method Step 3

Connect cathode of LED (flat side) to the collector (C) of the transistor.
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norberth4 months ago

Hi! Can this circuit work with a 3.7 volt battery?

sokbok1 year ago
im only using 3.7 V Battery, what might the 100K resistor value be changed to ?
wilbs719 sokbok7 months ago

try using a trim pot to get the desired performance while still on the breadboard, then measure the trim pot's resistance with your ohm-meter. Then solder in that value resistor. No Muss - No Fuss

p2man2 years ago
I did the same exact thing, but my LED is really dim. Any idea what could be wrong? I've progressed from it not working at all to the point there is dim light! :)
JamesNg7 years ago
I have tryed to use a Lithium Battery(CR2025,3V) to replace the 9V "BIG BATTERY". And,the 470ohm should be drop out.i think that the Lithium Battery may hide under the cap.
IMG_2167.jpgIMG_2168.jpg
p2man JamesNg2 years ago
Hi James, could you post a schematic of this please? Here is a picture of mine.
p2man p2man2 years ago
Sorry here it is.
photo.JPG
JamesNg p2man2 years ago
could yours work?
p2man JamesNg2 years ago
Nope :(
how long would the lithium battery last?
ATG ryugatana5 years ago
probably 6months-1yr....iam guessin...dependin on the time ur room is dark...computer motherboards use the same lithium cells...nd they last for lik forever lol....
=.=a
Sorry
I Don't know.
I just have tried the demo only.
ATG JamesNg5 years ago
yea i made mine the same way...works grt...nd is pretty discrete since evrything fits inside the bottle....
what resistor did you use between the transistor and the photocell???
I have tryed to use a Lithium Battery(CR2025,3V) to replace the 9V "BIG BATTERY". And,the 470ohm should be drop out....

of coz it depends on your photocell supply voltage and the LED working voltage range.
abbtech (author)  JamesNg7 years ago
Looks great James
Hi, I wired my thing the way the schematic said and my light stays on, and gets righter with more light.. PLEASE HELP
brighter*
tomx634 years ago
This thread was an example example!
nightlight_LED.JPG
I tried this one actually was pretty interesting. But wasn't succesful, when lI off the light the photocell light gets off and when light falls on photocell it glows. It became reverse :-P what should i DO ????/ plz do help :-(
post what you've got set up. i'll be glad to take a look at it to see if i can help. i'm an electronics newbie, but this is a very straight foward circuit and shouldn't be too difficult to troubleshoot.
I also have had trouble where when done as drawn the LED is brighter when exposed to light, but when I reverse the battery polarity it works fine. attached is a photo of what I did. in photo 51 I did disconnect a red wire so that I could take better photos
my images didn't upload
P1150949.JPGP1150951.JPG
mhkabir5 years ago
Can this circuit be modified to light up 30-40 LEDS on a 12v battery?Any help will be appriciated.
Basic electronics... if the supply voltage is 9v and the LED runs on 3.4 volts at 30mA (0.030 amps) then what you need to do is drop the excess voltage. So 9v - 3.4v = 5.6 volts.

We need to drop 5.6 volts at 30mA. So 5.6 / 0.030 = 186 ohms.

In this circuit he is running the LED with a 470 ohm resistor... so let's do that math...

5.6 volts / 470 ohms = 0.012 mA approx...

so he is running the light at about 1/3 brightness.

If you connected 30 LEDs in parallel, that would be 12ma X 12 or .360mA... 360mA total.

5.6 / .360 = 15 ohm resistor.

And the 9v battery would last 1/30 as long.

Another trick... to not need the resistor... if one LED uses 3.4v... then when connected in series... 4 of them would use about 10 volts. So connect 4 of them in series... call that 'module 1' then connect 9 modules in parallel... and you have 4x9 or 36 LEDs.

But again it is going to last 1/36 as long.

Reference: Ohms Law - http://en.wikipedia.org/wiki/Ohm%27s_law

This is very well written:

http://www.instructables.com/id/LEDs-for-Beginners/

Hope that helps.
Jerry
Yeah I would also like to know this.
t-bird mhkabir5 years ago
That is a question that I have also.
aswan23 years ago
How hard would it be to replace the LED with a piezo buzzer? Would I need to change out the resistors?
medaceina5 years ago
I used one of the other instructables (http://www.instructables.com/id/Bawls-Blue-Crystal-LED-Light/) as most of my inspiration but wanted to show what I made. I used 2 blue leds and 4 green inthe middle but the blue still shined through more but i left it alone because i was still happy with the results.

Heres the picture.
DSC_00011.jpg
both bottles look awesome. is that the natural texture of the bottle or did you fill the bottle with something that helps disperse the light? great job.
abbtech (author)  medaceina5 years ago
Looks great!
I tried this one actually was pretty interesting. But wasn't successful, when i off the light the photocell light gets off and when light falls on photocell it glows. It became reverse :-P what should i DO ????/ plz do help :-(
I just finished a red one and I'm working on another blue green one.
DSC_0002.JPG
demonstech4 years ago
hello folks, I tried this one actually was pretty interesting. But wasn't succesful, when i object the photocell light gets off and when light falls on photocell it glows. It became reverse :-P what should i DO ????/ plz do help :-(
james734 years ago
I need help PLEASE Im want to use a 5v trnsformer to photocell to a led i got ll my parts at radio shack. led is 7000 mcd 5ma 3.3-3.6max volts Im not sue if i got the right transistor mrkings are 2n/222/a338. when i get it to work it works opposite of what i want light turns on in light and off in dark. WHAT do i need to do
                                                                    
echoskope4 years ago
if anybody is wondering, the key resistance that the photocell needs to have is 62.693 MOhms. (Built the circuit in multisim). Any higher will cause the LED to light, any lower and it goes off.
vietbingo5 years ago
Here's mine One question, does the photocell's resistance means to the whole system? In above one, I use 500 - 50k photo cell. But currently, the shop that I bought that photo cell is out of stock. They only have 1k-200k now. When I use 1k-200k photocell, the led is always ON
photo0030p.jpg
My Work
Photo-0041.jpg
I've just re-modify the system with 2x100k Ohm instead of 100k Ohm

The system works fine in natural light (morning and noon)

At night, when I use neon light or other non-natural light, the led is *always* ON. What I should do in this situation?
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