SPDT Judco switch and two 1400ma current limiter boards

This is the most recent build info on how I assemble the driver for the Marwi lights

Here's a shot of the 1400 ma current limiter boards I use on the assembled Marwi P7 lights
These boards are machined on my CNC machine so that wires can pass through the boards when they stacked up on top of each other.

Note that I currently do not sell these machined boards or offer any technical assistance on assembling this driver stack.
I have found that very few are able to assemble tiny parts like this and make it work.
If you are very skilled, you can use a Dremel tool and a drill press to do the same thing I do to these boards on my CNC machine.

Click on Image below for a larger Image

This diagram describes the SPDT Judco switch switching and how it works with the dual 1400ma current limiter boards.

OFF - When the switch is off, the battery negative is disconnected from both boards and so the LED is off

LOW MODE - When the switch is on the Low mode, it connects the battery negative to one of the 1400ma current limiter boards.
This limits the LED current to 1400ma giving you a low power mode.

High MODE - When the switch is on the High mode, it connects the battery negative to both 1400ma current limiter boards
This limits the LED current to 2800ma giving you a High power mode.

Note that the SPDT Judco switch actually has 4 click positions.
(OFF) - (ON1 = low) - (ON1 & ON 2 = High) - (ON2 = low)
There are actually two low modes and one high mode because of the way this switch works internally
Each low mode just turns on one board. They are both the same, 1400ma of current limiting

Here's an animation of how the switch works

Assembly Notes:
The Judco switches I use are USA made push button switches that are very high quality.
I am using Rubber switch boots that waterproof the switch plunger on the Judco switches

You do not have to solder the jumper wire across the diodes.
I do it because I do not trust the tiny surface mount diodes and I also want to eliminate the small voltage drop across the diodes.
If a diode fails, the board will stop working and so I jumper across them to take them out of the circuit.
Each 7135 chip regulates 350 milliamps of current and so 350ma x 4 in parallel = 1400ma total
The diode is on the board for protection in case you hook up your battery backwards.

Normally, the 3.6 volt Battery + voltage comes down the center wire, goes through the diode and supplies the 3.6 volts to the chips.
If you think it is possible that you may install a battery backwards, it may be advisable to not jumper across the diode.
I use soldered together battery packs and so it is impossible for me to hook up my batteries backwards.
Some people use battery holders with removable batteries and it is possible to install your batteries backwards in a battery holder.

The two bare wires that I add to the switch, supply the battery negative to the current regulator boards.
When both boards are on, they are in parallel.
All 8 of the 7135 chips regulate 350 milliamps each x 8 = 2800 milliamps total.

If you have some fabrications skills, you can alter the stock current limiter boards that I sell and make this driver assembly
You can machine the boards with a Dremel tool rasp bit
The bottom board has one side removed so that a wire can pass by the board and go up to the top board
The top board has a notch so that the Battery + wire can exit out the bottom of the heat sink and go to the power cord.

Both boards have all the gold removed around the LED Minus hole on the back of the board
This prevents the LED - wire from shorting out to the Battery + area on the back of the board.
The LED - holes that pass through each board can be drilled with a 1/32" drill bit
See the board mod tip below.

You can probably make this driver assembly without using the very top copper wire attachment board

It takes a very small pointy tip on your soldering iron to do this fine work.
I use two different soldering irons to make this assembly.
A 25 watt pencil iron and a 40 watt pencil iron.
I sand the tip down on the 25 watt iron and then re-tin the copper tip.

Board mod tip

The center gold area on the back of the boards is the Battery + and LED +
The outer gold ring is the battery negative connection
You do not want the LED negative wire to contact the center gold area on the back of the boards.
Remove the gold area around the LED negative hole on the back of the boards with a Dremel.
The board on the right above shows how I removed all the gold around the back of the hole with my Dremel.

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This is the Judco SPDT switch	These are the modified 1400ma current limiter boards See the board mod tip above about the backs of each board
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Click on the images for a larger image

I also use a small circuit board that is the attachment point for the LED wires and the Battery + wire	Trim the switch wire lengths and remove the Red and Black jacket The white wire should be left about 1.5" for now See the images below
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Space is tight inside the Marwi housing. You need to reduce the size of the 18 gauge black and red switch wires. These two wires go to the battery negative on each current limiter board and cannot be a large diameter wire. Remove the red and black wire insulation all the way down to the switch body. Solder some 20 gauge solid core buss wire to each 18 gauge wire and bend them around the switch body as shown above. Snip the extra 18 gauge wire off right above your solder joint
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Click on the images for a larger image

Super glue the bottom board to the back of the switch to hold it in place Solder the bottom board negative wire to the edge of the board.	This shot shows the opposite side of the switch
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Click on the images for a larger image

Another shot showing the bottom board. The battery negative wire is soldered to the bottom board.
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Add 3 wires to the bottom board Wire 1 = The Battery + wire Wire 2 = The LED - wire Wire 3 = A short jumper across the diode Solder all 3 wires in place	Slide the top board down onto the stack. Solder the base of each wire Add a diode jumper to the board
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Click on the images for a larger image

A side view of the whole stack Add a piece of heat shrink to the top board negative wire Bend the wire and solder the wire to the top board ground	Slide the heat shrink up so the top board wire cannot short out on the edge of the bottom board
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Click on the images for a larger image

Slide the wire attachment board onto the stack Bend the wires over, trim them to length and solder them The outer diameter of this board fits inside the heat sink and keep things centered	I have soldered 3 Teflon wires to the attachment board. The Red LED+ wire, The Black LED- wire, and the Red Battery + wire The Battery + wire goes over and down through the notch so that the heat sink can slide down onto the whole stack.
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The heat sink and SSC P7 LED	Apply thermal grease to each surface
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Screw down the LED to the heat sink The contacts have some sort of clear coating Use an Exacto knife to clean the coating off the solder contacts	Slide the heat sink down onto the stack Red wire is LED + Black wire is LED -
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Click on the images for a larger image

Trim the wires to the proper length	Strip the wire ends and tin the ends with solder Add a bit of solder to the LED contacts
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Solder the LED wires to the contact points I do this with a 40 watt pencil soldering iron A small wattage soldering iron will not do this properly	Here's the completed assembly ready to be installed in the Marwi housing There is a side shot of this assembly shown below
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Click on the images for a larger image

Above Left: This picture illustrates how important it is to keep your LED solder joints as low as possible when soldering the LED + and - wires to the connection points. If you blob a bunch of solder onto the solder joints, and the solder joints stick up too high, it is possible to short out the LED connections on the rear of the metal reflector. We are working with a very low voltage (3.6 volts DC) and so arcing across the gap is not really an issue like it would be in a high voltage application. I machine the LED hole in the reflectors to fit very snugly around the LED. The LED has a hard black ring around the soft lens material. The reflector sits on that hard black ring. When the reflector is inside the Marwi body, it fits snugly and will not rock sideways and short out the connections. The heat sink slides into the body very snugly also and it will not rock sideways. The reflector and the heat sink stay in perfect alignment inside the Marwi body. Still, you must have good soldering technique when soldering the LED connections. Above Right: This picture shows how the heat sink assembly fits into the Marwi housing. Note that I have to resize the housing so that the heat sink fits very snugly into the housing. I have a tool that squeezes the rear housing down just a bit to make the heat sink a very tight fit. I want maximum contact area so the heat is drawn away from the heat sink and out to the Marwi housing. I am not showing the Marwi rear switch cap assembly in this shot.
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