Electrical paths in a flashlight

[lundeholm]

I'm about to do my very first flashlight mod (drop in driver swap) but I would like to confirm my basic understanding of the electrical paths in a flashlight before doing so. Does the following picture look alright to you?



Question: why are there two connections to the led from the driver board? I thought the bottom of the LED board was supposed to be electrically connected to the flashlight body to complete the circuit?

Also, is there a way to check for bad connections and short-circuits before turning on the flashlight after the mod? I don't want to risk shorting out the battery or destroying the driver :poof:

thanks

 

[mvyrmnd]

The body of the flashlight is the negative electrical path from the battery to the driver. The LED has it's own separate circuit on the other side of the driver.

(I can't see your image, but that's how it normally works.)

 

[lundeholm]

I uploaded to another image host, it seems to work now. Would it be possible to cut the black wire to the led and still make it work if the bottom of the led circuit board is connected to the flashlight body?

 

[CKOD]

I uploaded to another image host, it seems to work now. Would it be possible to cut the black wire to the led and still make it work if the bottom of the led circuit board is connected to the flashlight body?

No, a LED on a MCPCB is electrically isolated. Plus not all drivers have the Vin- and Vout- connected together. The AMC chips for example, the batt+ gets connected to the LED+, and the LED- gets connected to the regulator chips, which sink the current down to batt-

 

[Th232]

It shouldn't work if you cut the black wire, I believe part of the point of a MCPCB is to electrically isolate the LED from the heatsink. Between the LED and the aluminium that makes up the bulk of the board is an insulating layer so that all the pads aren't shorted together.

Edit: beaten to it!

 

[VegasF6]

As for testing for shorts, set your meter to ohms or diode check and check for resistance between the two points of concern. Say for instance between bare metal of the light body and the positive pad of your driver.

 

[lundeholm]

thank you guys, everything makes sense now :) now I feel comfortable in trying this mod, I even figured out how to handle the ohm setting on my multimeter lovecpf