Blue Bawls automatic LED light

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

Step 1 Gather the parts

Here are all of the parts that you need.

• 9 Volt Battery
• Photo-Cell
• NPN Transistor (2N 4401)
• Super Bright White LED
• 100K ohms Resistor
• 470 ohms Resistor
• 9 Volt battery Snap

Comments

[mhkabir]

Can this circuit be modified to light up 30-40 LEDS on a 12v battery?Any help will be appriciated.

[askjerry]

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

[Mike060187]

Yeah I would also like to know this.

[t-bird]

That is a question that I have also.

[aswan2]

How hard would it be to replace the LED with a piezo buzzer? Would I need to change out the resistors?

[medaceina]

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.

[medaceina]

Heres the picture.

[tomx63]

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]

Looks great!

[demonstech]

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 :-(

[medaceina]

I just finished a red one and I'm working on another blue green one.

[tomx63]

This thread was an example example!

[demonstech]

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 :-(

[tomx63]

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.

[demonstech]

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 :-(

[james73]

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
                                                                    

[echoskope]

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.

[vietbingo]

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

[vietbingo]

My Work

[vietbingo]

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?

[vietbingo]

Everything work fine know, I connect 2 photo cells parallel together Thanks for a great instruction :)

[meissler]

Finished mine with a beer bottle + put some glass in :D

http://i32.tinypic.com/2jbs6iw.jpg

[abbtech]

Very cool looking!

[huor]

ohh by the way what kind of resistance values have your photoccell???

[abbtech]

It is high resistance when in the dark and low resistance when in bright light.

[meissler]

Could you explain why you need high resistance when it's dark and low resistance when it's bright? I would think it would be the opposite- high resistance when it's bright so not much voltage reaches the LED. Maybe it has something to do with the transistor? Thanks for clarifying.

[abbtech]

Yes, the transistor is the reason for this.

[JamesNg]

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.

[ATG]

yea i made mine the same way...works grt...nd is pretty discrete since evrything fits inside the bottle....

[ryugatana]

how long would the lithium battery last?

[ATG]

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....

[JamesNg]

=.=a
Sorry
I Don't know.
I just have tried the demo only.

[Illuminati]

what resistor did you use between the transistor and the photocell???

[JamesNg]

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]

Looks great James

[confusedxvii]

when i was done and finished i did have to sauder the emitter to a wire just to let you know

[IreallyDontKnow]

does it half to be a conductive cap? or could i bootleg a cap to broden my customization..and how would you make the led waterproof?

[DarkEnigma]

Is there anyway you could explain the schematic? I'm new to electronics in general and don't understand to the fullest of what that means.

[rmcnaugh]

help. my battery keeps over heating (especially on the positive side) and i can't figure out why. Is it because i have don't have the caps for the battery top? I'm just using the wires connected to the battery. also I added an on/off toggle switch. please help.

[rmcnaugh]

this might be a silly question, but how do I check for shorts? I have a a radioshack analog multimeter. Should I use that, and what am I looking for? rmcnaugh