Hello,
As I told in another post my need is to switch-on remotly a powerfull source of light under 300gr (drone purpose)
in the FW21 pro manual FAQ i can read :
“if there is a short between neg.and switch tube, the lamp is constantly on”
is someone have an idea to find the way to do this “short”? (to make an external switch)
thank you in advance for your help
a couple of things. once you add weight to a drone and push it over 300 grams you have to follow rules and regulations for a UAS over 300 grams. registration etc. another thing, is the vehicle going to be able to carry the weight of a 21700 flashlight?
to remote operate a light, i would try wiring a relay to the ‘short’, and a radio transmitter to operate it.
Hi DudeMan,
will show what i am doing but the drone part is already ok (my mavic can carry 3-400grammes)!. (the radio transmitter also)
What i don’t know is “this short” on the FW21, how to wire it (from where to where)
oh, sorry. thought the vehicle was sub 300 grams.
sounds like if you attach the batteries negative to the battery tube the light will be on. put the switch, relay etc between them.
make sure it can handle the amperage.
can someone confirm that is how it’s wired?
Do you have any unused command or actuator signal lines on the drone controller and on the drone itself?
That signal could be used to drive a relay or transistor to close a circuit path between the tube and the battery negative.
thanks for your answers
FYI the relay part is ok, I use an independant remote
I manage to disassemble the tail of the FW21 pro ( even it is written “don’t disassemble the tail”)
so I made the contact between the batterie negative to the tube… and the result is
…
it blink one time, as when you screw the head. 
any idea to make this light directly at full power ?
am i this only one to test this type of remote hack on flashlight ?
Sorry i don’t know that flashlight, but the previous advice may have been in error.
Does that light have a push button switch, and does it have different modes depending upon how many clicks of the switch, etc?
If so then i would guess that the drone control relay should be wired in to the switch contacts, i.e. the drone relay will have the function of the push switch.
Maybe someone here has done a tear-down review to reveal the inside circuits and switch details, hopefully with pictures.
That is a cool ring of fire—how do you form that cylinder with even top and bottom rings?
The FW21 Pro is an e-switch light. That means it needs permanent power and a switch signal which controls all the functions. You could enable momentary mode where it is on as long as the switch is held down. But it must be enabled again after each power cycle.
Power goes through the outer tube or threads of the head while the switch signal goes through the inner tube or ring on the driver.
Also please note that the flashlight will overheat in just a few seconds on full power. I think it will draw about 20 A or more, so be prepared. Being a direct-drive driver it also relies on the internal resistance of the battery. So if you provide more than 30 A without voltage drop to about 3.5 V it will be destroyed pretty easily.
Reflections on the water.
Hello, thank you kennybobby , i thinked it would work with a relay direct on the switch but as SammysHP told later it is an “e-switch” which is different
SammysHP, thank you for sharing your knowledge !
I dissasemble the tail and understand what you said about permanent power and switch signal. (I tested it)
I know have to find a tail remplacement to wire the modification without killing the normal use of this flashlight.
is anyone know where to find one ? does all “e-switch” are the same, do I have to ask lumintop or they are alternative ?
(here is the desassemble pictures)
you may want to consider finding a dedicated flashlight that has remote switches available. i couldn’t find any for the FW21.
It seems that the control processor requires it to be powered at all times. This may be a safety feature if it is also monitoring the Lithium cell to provide a BMS function with protection for charging and discharging, temperature, etc.
The e-switch does not carry high current or power, but is only a signal line switch to send a sequence of commands to the processor. If a relay were used to bypass the switch then your drone controller would toggle the relay to emulate the clicks of the e-switch. If you wanted to retain the use of the e-switch, then the drone relay would be wired in parallel to the e-switch. A tiny hole and tiny wires could be used to get access. Or i think you are trying to get another tail so you can have dedicated tails for either land or sky use, Just my guess of how it might work.
[edit] the @Dude has found a nice remote, very clever