kosPap
Flashlight Enthusiast
I was commissioned to make a 1AA drop-in for his Surefire 6P by a friend of a friend.
Driver Selection
Now there are not many good 1AA drivers at 17mm out there –if any- and a look at my stock showed the existence of the old DX sku7880 driver.
But it I a very complicated driver with many modes organized in 3 groups and a complex changing method.
My next option was a version of the same design (the venerable RV7 drivers) sold by ShiningBeam around 2010-11. But it is a 14mm driver and some kind of adaptation o the 17mm drop-in socket should be done.
Specs
* Regulated circuit board designed for Cree XP-G, XP-E and XR-E emitters
* 3 modes: Low>Med>High
* Voltage input: 0.8V -1.7V
* The memory feature will memorize the last mode
* Output current: 900mA on high, 200mA on medium, and 25mA with low mode
* Boost circuit board
* 14mm base board diameter
* Lead wires already soldered on board
After testig I found out that:
- The driver is a true constant current driver. Indeed it gives a flat output until the battery crap out.
- Light level is done by current regulation. No PWM. But this comes with a disadvantage. In low modes there is a LED tint shift towards the blue.
- Output is totally related to LED Vf. I do not think it is possible to get the spec'ed 600mA.
Bad news: of the 2 pieces of this particular driver I had in stock I managed to fry one during the build. That is unfortunate 'cos I was planning to offer a second 1AA drop-in of the kind for sale in CPF.
Adapting the Driver
I decided to use a method I have done before and it is clean and working.
Use a blank 17mm driver board and piggyback the 14mm driver on it.
Donor was a 4xAMC7135 no controlling chip driver. With components removed, thre is a clean flat surface, with a hole in the center for a jumper wire to pass.
But then another problem surfaced. With driver being already quite high, there as no headroom in the drop-in. So I resorted to adding a 17mm to 17mm driver adapter ring.
But then the drop-in become a bit longer than a what a 6P would accept, a phenomenon that we used to face with the Derrelight drivers way back then.
The head will not screw down flush, but the 1mm void is easily covered by an O-ring
The Materials
Kapton Tape
Double sided self-sticking thermal pad for heatsinks
Some wire and for driver hookup.
Driver
XP-G2 3C (chosen for maximum throw)
Stripped 4x7135 driver board
17mm to 17mm adapter ring
Fasttech XP-E Drop-in
Assembly
While the driver's inductor does not touch the drop-in wall, I played it safe and stuck a piece of Kapton tape on it.
The LED was glued with thermal epoxy. It was centered by a similar reflector and tow piece of shanks were positioned in the wire openings to hinder the LED star from turning over them.
Soldering the connecting wire on the driver.
Chamfering of the 7135 board edges to sit lower on the socket (the whole genre of these boards are a bit thicker than the drop-ins sockets).
Sticking the heatsink pad on the adapter board.
Soldering two –current connecting wires between the rims of both boards.
Semi-Potting of the driver.
Board sandwich.
Thick hard center spring installation
Making an AA battery adaptor for the 6P
Without access to a lathe and trying to keep cost down I opted for a homemade battery adapter. The goal was to bring AA battery height to the 2xCR123 length (67mm)
Parts were an AW RCR123 to 17500 adapter plug (he sold this for charging RCRs on the WF-139 charger), and several lengths of heatshrink wrap.
the Final Products
The Saga Continues…facing off the Parasitic Resistance Monster
While the 6P is simple in its build, it is very complex in the principle of its operation.
It depends on the battery stack asking as a piston on the Z41 switch and driven by the help of the lamp and switch springs.
But the springs are not that powerful and there is no hard contact between lamb, batteries and switch.
For 6 volts there is room for some voltage to be lost, but starting at 1.5V to be boosted at 3.2V there is no room for drain.
The final owner also wanted to use a Solarforce FWD click switch, and that complicates things further as it makes for more room in the tube to be taken by spring length. Which means uncompressed springs and longer wire to act as a resistor.
I ended up making one more 1.5mm thick adapter and advising the user to use the original Surefire switch.
For reference I go this measurements on high:
130 lumens of a single adapter
205 lumens on both adapters and Solarforce switch
245 lumens on both adapters and Z41 switch
In retrospect one needs to shorten spring length and make a 30mm plug, cos the room from drop-in base to body rim runs at 83mm..
Driver Selection
Now there are not many good 1AA drivers at 17mm out there –if any- and a look at my stock showed the existence of the old DX sku7880 driver.
But it I a very complicated driver with many modes organized in 3 groups and a complex changing method.
My next option was a version of the same design (the venerable RV7 drivers) sold by ShiningBeam around 2010-11. But it is a 14mm driver and some kind of adaptation o the 17mm drop-in socket should be done.
Specs
* Regulated circuit board designed for Cree XP-G, XP-E and XR-E emitters
* 3 modes: Low>Med>High
* Voltage input: 0.8V -1.7V
* The memory feature will memorize the last mode
* Output current: 900mA on high, 200mA on medium, and 25mA with low mode
* Boost circuit board
* 14mm base board diameter
* Lead wires already soldered on board
After testig I found out that:
- The driver is a true constant current driver. Indeed it gives a flat output until the battery crap out.
- Light level is done by current regulation. No PWM. But this comes with a disadvantage. In low modes there is a LED tint shift towards the blue.
- Output is totally related to LED Vf. I do not think it is possible to get the spec'ed 600mA.
Bad news: of the 2 pieces of this particular driver I had in stock I managed to fry one during the build. That is unfortunate 'cos I was planning to offer a second 1AA drop-in of the kind for sale in CPF.
Adapting the Driver
I decided to use a method I have done before and it is clean and working.
Use a blank 17mm driver board and piggyback the 14mm driver on it.
Donor was a 4xAMC7135 no controlling chip driver. With components removed, thre is a clean flat surface, with a hole in the center for a jumper wire to pass.
But then another problem surfaced. With driver being already quite high, there as no headroom in the drop-in. So I resorted to adding a 17mm to 17mm driver adapter ring.
But then the drop-in become a bit longer than a what a 6P would accept, a phenomenon that we used to face with the Derrelight drivers way back then.
The head will not screw down flush, but the 1mm void is easily covered by an O-ring
The Materials
Kapton Tape
Double sided self-sticking thermal pad for heatsinks
Some wire and for driver hookup.
Driver
XP-G2 3C (chosen for maximum throw)
Stripped 4x7135 driver board
17mm to 17mm adapter ring
Fasttech XP-E Drop-in
Assembly
While the driver's inductor does not touch the drop-in wall, I played it safe and stuck a piece of Kapton tape on it.
The LED was glued with thermal epoxy. It was centered by a similar reflector and tow piece of shanks were positioned in the wire openings to hinder the LED star from turning over them.
Soldering the connecting wire on the driver.
Chamfering of the 7135 board edges to sit lower on the socket (the whole genre of these boards are a bit thicker than the drop-ins sockets).
Sticking the heatsink pad on the adapter board.
Soldering two –current connecting wires between the rims of both boards.
Semi-Potting of the driver.
Board sandwich.
Thick hard center spring installation
Making an AA battery adaptor for the 6P
Without access to a lathe and trying to keep cost down I opted for a homemade battery adapter. The goal was to bring AA battery height to the 2xCR123 length (67mm)
Parts were an AW RCR123 to 17500 adapter plug (he sold this for charging RCRs on the WF-139 charger), and several lengths of heatshrink wrap.
the Final Products
The Saga Continues…facing off the Parasitic Resistance Monster
While the 6P is simple in its build, it is very complex in the principle of its operation.
It depends on the battery stack asking as a piston on the Z41 switch and driven by the help of the lamp and switch springs.
But the springs are not that powerful and there is no hard contact between lamb, batteries and switch.
For 6 volts there is room for some voltage to be lost, but starting at 1.5V to be boosted at 3.2V there is no room for drain.
The final owner also wanted to use a Solarforce FWD click switch, and that complicates things further as it makes for more room in the tube to be taken by spring length. Which means uncompressed springs and longer wire to act as a resistor.
I ended up making one more 1.5mm thick adapter and advising the user to use the original Surefire switch.
For reference I go this measurements on high:
130 lumens of a single adapter
205 lumens on both adapters and Solarforce switch
245 lumens on both adapters and Z41 switch
In retrospect one needs to shorten spring length and make a 30mm plug, cos the room from drop-in base to body rim runs at 83mm..
