Flashlight 3xAAA replacement

​I got a flashlight as the first ever kind gesture from my apartment management for the most recent schedule 24+hours maintenance power shutoff. It has a very nice reflector for a square LED and a smaller chip inside that controls the 3 operating modes. 

Off course I had to open it up right away.  It uses 3AAA on the usual battery holders for cheap flashlights.  I smell trouble or an opportunity for some corrective active.  I am not fond of using odd numbers of AAA batteries as I have been using rechargeable since NiCd days.  I don't know if they use a constant current driver, so could be trouble for 3 fully charged NiMH (1.4V x 3 = 4.2V) with low internal resistance.

I used the parts from a 5V booster board I bought from the usual places, but modified the feedback divider for 3V which is just bright enough to drive LED, but low enough to not go into thermal run away.

U1 has the same pin out as the unknown part used on the board.

As my replacement board has 3 contacts - 3V and 2 GND, I had to move the battery off centered to avoid shorting the 3V output to the front of the PCB.  

I used easily soldered and bent metal strips  to form a battery guide and the hinged -ve terminal.  They are used to crimp the end of plastic mesh for store bought onions and garlic.  

My battery terminal help to make better connection between the offset battery and the spring loaded terminal the of the flashlight cap to the right side of the picture below.

It also acts as a pull tab for the PCB assembly when it is time for replacing battery.

Attack of the blinking dimming flashlight

I would never have thought that the blinking dimming light movie tropes is being kept alive by poorly made flashlight clicky switches.

I managed to extract the mechanism that was pressed fitted into the end cap of the flashlight.  They use some iron strips as part of the contact.  There are 2 such contacts in series and they gets even worse as I use the switch for the boost supply with about 3X currents.

I cut2 pieces of gold plated (15um) pin from a 2mm connector.

I soldered them onto the contacts.  The contacts needed to be bent flat as the pins adds extra thickness.

There is a metal piece that looks like a top in the previous picture.  I had to bent the circular part down to make more clearance for the pins. I reassembled the switch and soldered a short piece of bare stranded wires.  This wire helps to make better contact to the side wall of the end cap.

Unfortunately the plastic they used is too soft and I do not have the right jig to press it back in place.  If there were a time I wish I had a 3D printer, this would be it.

Anyways this fix got rid of the flimsy flickers and the light a lot brighter.