If you have an old incandescent flashlight left in forgotten storage box.You can rebuild it to be powerfull bright LED emitter flashlight.No need to buy new expensive LED flashlight,invest less than 5 dollars and home level technical skill.
Step 1: Materials and Tools
Materials preparation :
1.Old flashlight bulb.
2.Resistor 1 ohm.
3.LED emitter 3W 3.7VDC 180 lumens 700mA
3.Hard epoxy putty.
Step 2: Prepare LED Emitter Bulb Body
Break old flashlight bulb glass.Becarefull of exploded glass pieces.(Use thick cloth or bag to cover it before breaking)
Take off all matrials inside.Melt lead at the bottom of the bulb by soldering gun.There is a hole at the tail for wiring.
Step 3: Install Bulb Body+ Resistor+ LED Emitter+Epoxy Putty
Put resistor inside the bulb body.Solder another resistor leg with positive pole of LED emitter.Solder negative pole of LED emitter with bulb body.And solder resistor leg at the bulb positive pole,cut resistor leg off.(See pictures)
Resistor will protect LED emitter from over current.
Check that there are no material touching to the ground to prevent short circuit.
Put hard epoxy putty around LED emitter to fix it in place.Hard epoxy putty is heat resistance and electrical insulation.Do not use non heat resistance epoxy because when turn on LED emitter will get hot.
Wait around couple of hours for epoxy cure.
Step 4: Install LED Emitter Bulb in Old Flashlight
Screw completed LED emitter bulb back in the old flashlight.If the flashlight kept long time.It's necessary to clean electrical contact and change old oxided cable and on-off switch.Otherwise the LED bulb will blink.
The LED emitter works good with 2 AA 1.5 volt alkaline batteries or 2 AA rechargeable 1.2 volt Nicd batteries.(Lower brightness due to 2.4 volt supply)
Try to do it yourself ,save your money and utilize your leisure.