help build emergency rechargable flash light

M

mohantamil

New Member
how to build emergency rechargable flash light using diodes,resistor,electrolytic capacitor,rechargable battery,and 21 led builds
 
I just bought one at Harbor Freight Tools for $2 that runs on 3 AAA batteries..

How exactly to you plan to build the reflector, lense, case and all?

The circuitry is trivial, the mechanical assemblies are not.
 
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Finals time... Joy.
 
In your Part list is no active semiconductor.
I would solve that problem with a NE555 astabile Multivibrator and a "Power" Mos FET Transistor.
When using the C-MOS Variant of 555 ( 7555 ) the Multivibrator draw very low current.

For the LED's you can use Low Current ones, when they are bright enough.

An astabile Multivibrator with 2 Transistor's is also possible.
But I think you have to install an additional driver Stage ( FET or Darlington Transistor ).

What kind of accu you want to use? Lead, NiMh, LiIon, LiPo, or LiFePo4 ?
All of them have assets and drawbacks.
I think a good choice for the Operation Voltage is around 12V.
So you can built strings with 3 or 4 LED's in serial configuration. 7 Strings with 3 Diodes will give you 21 LED's
 
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one of my friend told me that china made emergency flash light is available using this circuit with 9 led .pls upload any body this circuit.thx in advance and how to use it breadboard
 
There is a way to build an off line rechargeable light using only diodes, resistors and capacitors, it is a charge pump design that runs off the AC line. I have one old (cheap) rechargeable flashlight that runs off two AA NI-CADs that uses that type of design. I don't have a schematic.
 
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Search with google for " LED Blinker schematic ".
e.g. you get such results: **broken link removed**
or such one: **broken link removed**

There are thousends of such schematic's in the Internet.
 
Here is a schematic of how to make a light than runs off the AC power using only diodes, caps and resistors. It also charges the battery.
 
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If you want automatic activation on mains power failure, you can connect a FET in like so...
 
The circuit I posted works, it is the one in my little wall flashlight that stays plugged in all the time. I recall it puts about 50 mA constant current into the batteries. I am using NICAD "AA" cells in it. It's been working for many years.
 
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