ok here is what i have. this is the diagram i have and used:


i replaced the LARGE CAP with 2 1.2volt ni-cd batteries.
the LED is a 3v blinking led from RadioShack

my problem is the 100K resistor should turn off the LED when the light in the room is on.

the solar panel I'm using puts out about 1.4v in average room light and 2.34 in sunlight. the higher the resistor the darker it should be for the LED to turn on correct? i even had 2 10m resisters in series and the only way i could get it to shut the light off is direct sunlight or my 2million candle powered flash/spot light.

it seems the led is always flashing unless direct sunlight hits it. what resistor should i use? higher? lower? i'm lost.

 

Ok here is what i need to do. i want to be able to fit a capacitor into a 35mm film canister with an FLED and have it solar powered. i have a solar panel from a garden light, and 1 1.2v ni-cd battery. i may need another for the led to light. can any one help me out? i want to do an LED OFF during lighted hours, and not to turn on until DARK. i know this can be done with a transistor and a resistor. i built a circuit from this project ( http://www.instructables.com/id/EOEM3MOZFEEVYE004P/ ) and i can't get the LED to shut off. no matter what i do for the resistor size.

i have everything wired and soldered up with 3 changes.
change 1 is a 3v blinking led
change 2 is 2 1.2v ni-cd batteries 500mah i think each ( would like to replace with a capacitor but don't know what size to use. i need it to run about 4 to 5 hours once it gets dark.)
change 3 is the resistor. i have even put in a 10m resistor and it keeps flashing in daylight. not sunlight but daylight. what am i doing wrong. oh and i have a 1k resistor inline on the positive side of the LED for safe measures.

ok i'm still stumped. been on this all day.

if this can't be done how long would an Flashing LED run on a 2aaa alkaline setup?

Thanks in advance.

 

Go to the website of a battery manufacturer like Energizer and look at the datasheet.
Two AAA alkaline cells begin at 3V then drop to 2.4V in 95 hours at an average current of only 10mA. It drops to 1.6V in about 140 hours.
What is the lowest voltage for the flashing LED?

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hi,
As 'agu' points out, its running from the battery.

Ive redrawn your circuit with battery in place of the cap, its clear whats
happening.

EDITED: Bty polarity! [agu ]

Attached Images

ldr1.gif (12.1 KB, 39 views)

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Eric
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Hi Eric,
I think your battery is backwards.

Attached Images

dark activated LED.GIF (16.4 KB, 27 views)

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the flashing led is a radio shack led.
Here is what was on the back of the pack:
Forward Supply Voltage:
3.0 Typical, 3.8 MAX
Luminous intensity:
880mcd at rated max
Peak Emmisions Wave length:
660nm Typical
Viewing Angle:
20°


there are a cople of ways i would like to make this:
Solar > charging a capacitor
Solar > charging a battery(s)
battery > with a photo-cell
The ideal one is the Solar charging a capacitor. but i'm new at this and am not sure what cap to use. i have been ripping apart old computers and computer power supplies to rob parts and play but to no success yet. any tips hints or diagrams would be GREAT.

Thanks
TNS

PS where do you guys in the states get your parts online? Radio Shack it outrageous but the only thing around for a quick grab and fix.

 

I think i found one problem.
The garden lights i robbed the batteries and solar panel out of have only ONE battery in each light. so i take it the LED is a lower voltage led. like 1/2 the 3v i have now. so when i added the other battery increasing to 3 volts (aprox) the solar cell could not produce enough voltage to trigger the transistor. am i right? in direct sunlight the single panel could only produce 2.34v. i added another panel to the circuit in parallel and nothing new happened. then i added it in series and when in sunlight now the led goes off. guess i just needed more Umph. i still would like to learn now to do this with a capacitor(just dont' know what cap to get). or is there a way to up the voltage output of a 1.2v battery to produce 3v to the led?

thanks again. you guys are great.

 

Solar Garden lights that have a single 1.2V battery cell use 1.8V red, orange and yellow LEDs or 3.5V white LEDs.
They have a voltage step-up circuit inside.

A capacitor cannot power an LED for very long. A battery has much more capacity.

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[quote= or is there a way to up the voltage output of a 1.2v battery to produce 3v to the led?
QUOTE]

hi,
Google for 'joule theif'

example:
http://www.emanator.demon.co.uk/bigclive/joule.htm

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NICE. Thanks "E"

 

ok having a hard time finding cheap ferrites. any hints or places to buy? is there another way to build something like this without ferrites? transistors maybe?

 

hi,
You can quite often find these small ferrites on old pcbs, usually slid over the ends of components as noise suppression.
In the psu area of a S/H piece of equipment is a good place to start looking.

Transistors will not get the job done on their own.

Where are you posting from?

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???? PSU? S/H? you lost me. i'm a newbie but a fast learner.

I'm from NY

This looks interensting.

 

Ok here is what i found. i have some old computers all around so i ripped some junk apart.

Picture attatched.

Attached Images

ferrite.jpg (36.3 KB, 28 views)

 

Use a little ferrite bead or anything other than that crappy flooring nail inductor which will give poor efficiency due to the eddy and hysteresis losses.

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