Coin Cell Flashlight

Simple to print & assemble.  Current limiting for the LED is achieved through the cell's internal resistance so no external resistor is required.

Required parts:

The design is compatible with T-1¾ style, 5mm diameter LEDs with leads lengths of 18.5mm for the anode & 17mm for the cathode.  If your LED has longer lead lengths then you will need to trim them accordingly.  Separate the leads a little so that their ends have a spacing of approximately 5mm.  

Assembly Instructions:

1. Insert the LED in the LED holder by aligning the flat-edge of the LED package with one of the holder tabs then push the package down so that it seats in the inner rib of the holder; 

2.  Confirm the LED is correctly seated by measuring the height of the dome past the holder.  It should measure approximately 3.8mm.  Failure to properly seat the LED could prevent the flashlight from working properly; 

3.  With the LED in the holder, position the assembly so that the longer lead (anode) is facing the same side as the power button on the main part;

4.  Align the LED leads with the two holes in the main part & slide the LED assembly through all the way into the main part with a bit of force.  The LED assembly will click into place & seat into the main part such that both surfaces are flush;

5.  Place the coin cell into the holder, making sure that the polarity is correct; i.e. +'ve marking on battery with with +'ve marking on battery holder;

6.  With the positive side of the button facing the power button on the main body, slide the battery assembly all the way through;

7.  Align the holes in the battery holder & main body from the back side & insert the screws.

Troubleshooting

• Light does not come on:  The LED leads are too far apart.  Bring them closer together.
• Light does not turn off:  The LED leads are too close together.  Separate them.

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