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SMD+ Kit
Luxeon LED with DC/DC |
- New Swappable Module Device - Illuminator SMD - a Swappable Module Device (SMD) with Luxeon LED and DC/DC regulator that maintains constant light output over the life the batteries Drop In Luxeon LED Conversion for MiniMag, Brinkmann and other 2AA aluminum Flashlights
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Do-It-Yourself SMD+ Kit Assembly Instructions
| The SMD Kit
First, again, for the record, this is not an elegant design, and perhaps breaks nearly all the good engineering practices possible. It is however, a cheap and simple voltage boost circuit that can drive a Luxeon at (SMD Kit ~ 350ma), or above (SMD+ Kit ~ 500+ma) the recommended current levels. Components for this kit were selected to be compatible with basic assembly skills. The larger size of the components used in this kit allow for ease of handling, installation and soldering. Successful completion of the assembly tasks outlined here should be easily accomplished by most hobbyist with little trouble. If you assembled the old ILL PILL Kit, then this circuit should pose no problems for you. The new SMD+ kit features an output diode and capacitor for increased current and true DC output. A super low forward voltage drop output Schottky diode feeds a 47uf tantalum capacitor which stores a charge maintaining current flow during the inductor charge cycle, providing more total current output to the Luxeon. Note that the output capacitor is rated for 10VDC, so the converter can also safely power 5 watt Luxeon LEDs. With the SMD+ Kits components, a module can be built into a circuit package that will replace the incandescent bulb and socket in popular 2AA flashlights to transform them into bright LED flashlights. This kit is intended for use with 1 watt Batwing (low dome) Luxeon LEDs and NX05 optic. It can also be used with 1 or 3 watt Lambertian (high dome) Luxeon LEDs, but results with the NX05 lens can make for difficult beam alignment. Use with high dome Luxeons and reflectors require advanced modification to the flashlight and reflector. Instructions will be added at a later date. |
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First, take inventory of the kit. You
should have two circuit cards, IC, inductor, diode and capacitor.
You will need to supply a Luxeon LED for use with these five parts to make the SMD. |
Please read through
all the instructions so you are familiar with the steps before beginning.
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| Step 1. Soldering the
IC
NOTE: If your kit came with the IC already soldered in place, skip to Step 2 |
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Position the IC on the circuit
card as shown in the drawing. It may be beneficial to use a small drop of
epoxy under the chip to keep it in place during soldering. If you use
epoxy, use only a very, very small drop; you don't want it oozing out from
under the chip and interfering with the solder flow.
TIP: Before doing any soldering, you can insure there are no "wisker" shorts on the circuit card by checking for isolation between the three areas of the circuit card. Set your meter to measure resistance and check between GND and V in, between GND and V out, and between V in and V out. They should all be isolated from one another (measure infinite resistance). |
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It is usually easiest to solder the lower right pin (pin 5) first, which will anchor the IC in position for soldering the remaining pins. Work very fast; do not apply heat for more than one second at a time, and allow the circuit board to cool between soldering pins. If possible, place the circuit card on a piece of aluminum or other metal surface to help dissipate the heat. Solder all the IC pins, letting things cool off before moving on to the next pin. Check your work; you may need to use alcohol to clean any flux residue off to verify that there are no solder bridges or bad solder joints. |
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Solder all the IC pins, letting things cool off before moving on to the next pin. Check your work; you may need to use alcohol to clean any flux residue off to verify that there are no solder bridges or bad solder joints. |
| Step 2. Soldering the Inductor |
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Position and solder the inductor as shown in the drawing. Be sure the inductor body is inside the edge of the circuit card. |
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If you have solder paste for
surface mount devices, its use makes soldering the inductor very easy.
If using regular rosin core solder, it may be necessary to heat the copper pad for several second before the solder will flow. The inductor, being just wire and ferrite material, can take more heat than other components. But don't over do it either, use a three second rule here; apply heat for no more than three seconds before stopping to let things cool. |
| Step 3. Test the Basic Circuit |
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It's a good idea to test the basic
function of the circuit before proceeding. It is easier to correct any
solder bridges or other soldering problems before installing the rest of
the components.
At this stage, the circuit is tolerant of open circuit conditions. Connect 2AA cells (3V) to the V in (+) and GND (-). You can connect a Luxeon between the V Out and GND to verify operation, or measure the output with a volt meter. Most volt meters will read something close to 3.1V on a DC scale. This is because you are measuring the high frequency pulsed DC output from the converter, and the reading is therefore not very accurate. |
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An easy way to test the circuit is to use
a test clip to connect to the GND. Connect the other end of the test clip
to the battery negative (-) and Luxeon or meter negative (-) terminal.
Then you can just touch the power in (battery +) to the V IN, and touch
the Luxeon or meter positive (+) to V Out to verify proper
operation.
At this point in the assembly you can add a Luxeon diode and the contact board to finish the assembly. However, without adding the diode and capacitor as shown in the next steps, the circuit will operate at a reduced output. For best performance, install the diode and capacitor. |
| Step 4. Mounting the Diode |
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By now, you've probably been wondering
how that big diode is going to fit on the circuit card.
It's going to sit piggy back on top of the IC as shown in the drawing. |
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Form the leads as shown. Pay attention to
the polarity.
Bend the diode lead marked with line as shown. Use an Xacto knife to carefully lift the lead away from the bottom of the diode. Bend it up towards the diode top, but not flush against the body. Trim the lead length even with the top of the diode case. Straighten the diode unmarked end lead as shown. Use an Xacto knife to carefully lift the lead away from the bottom of the diode. Bend it out a little and then straighten with needle nose pliers.
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The formed diode should look like these examples. |
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Mount the diode on top of the IC as
shown. A small drop of 5 minute epoxy can be
used to aid in soldering and strength of the finished assembly.
The green line in the drawing shows proper positioning of the diode edge in line with the edges of the two Luxeon mounting holes. The diode will be offset a little to the center of the board compared to the IC as shown. |
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This photo shows the diode in the proper
position.
It may also be a good idea to check clearances using the capacitor as a gage for proper fit in accordance with Step 5 instructions. |
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Solder the unmarked end of the diode to the V Out section of the circuit board. Usually a solder bridge can be made between the lead and circuit board with little trouble. However, it may be necessary to use a short piece of bare wire to make the connection if needed. |
| Step 5. Mounting the Capacitor |
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If you have solder paste for
surface mount devices, its use makes soldering the capacitor very
easy.
If using regular rosin core solder, it may be necessary to apply a thin coat of solder to the circuit board and capacitor lead before attempting to solder the capacitor in place. It may be necessary to heat the circuit board until the solder flows, then quickly place the capacitor into position to achieve a good solder joint. Mount the capacitor with the banded end pointing up. Solder the bottom contact to the GND section of the circuit board. Make sure the body of the capacitor is inside the edge of the circuit board. |
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Side view drawings for reference. |
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Next, apply a small amount of solder to the top capacitor and diode leads soldering them together. | |
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Caution - Do not apply power to the
circuit from this point forward without a load attached!
This is a current source device circuit, and without a load attached, the circuit will generate ever increasing voltages attempting to reach regulation current level. Over voltage of the output capacitor and IC is almost instantaneous, causing destruction of the components. Do not apply power without a proper load (Luxeon) attached. Even brief intermittent load open connection can damage components, including Luxeon LED from output capacitor over voltage discharge. |
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| Step 6. Mounting the Luxeon Emitter |
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Straighten and bend the emitter leads backwards as shown in the photo. Test fit the emitter leads in the holes of the circuit card to make sure they fit ok; trim width as necessary. Note that the hole is counter sunk for the positive Luxeon lead (the one with the tab next to it) to prevent the lead from shorting to the copper surfaces. |
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Mix a small amount of thermal epoxy such as Artic Allumina or Artic Silver for use in mounting the emitter. Apply a thin coat to the back side of the emitter and observing polarity as shown in the photo, insert the leads through the holes in the circuit card. Do not use too much epoxy, you don't want a bunch of epoxy oozing out from under the emitter, as you will need to solder close to the Luxeon body later. |
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Do not bend over the Luxeon leads, but leave them straight for now. |
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Remove the flashlight head and set it a
side for later.
Remove the bulb and pry off the top of the bulb switch socket, and push the plastic assembly inside out the end of the battery tube. |
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Carefully drop the circuit card into the
battery tube, emitter end first. Next, slowly insert two AA cells and install the tail cap.
NOTE: As a good rule of thumb, since we don't want any electrons flowing yet, insert the first battery negative end first (backwards), and the second battery positive end first. This will insure no power can flow by accident. |
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Now, remove the front bezel and window from the head, and screw the battery tube into the head. Hold the head stationary, and screw the battery tube into it a few turns. Now, screw the battery tube back and forth while looking into the head at the emitter. If it is not perfectly centered, you should be able to see the offset when the emitter rotates and make adjustments. When you get the emitter positioned so that it appears to rotate without any offset, it will be perfectly centered. Set this aside for at least 30 minutes to allow the epoxy to set up. |
| Step 7. Soldering the Luxeon cathode (negative lead) |
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After the thermal epoxy has set up, with the LED board still in the battery tube, remove the head and set it aside. Clamp the battery tube to prevent movement during soldering, and carefully solder the negative lead of the Luxeon to the top of the circuit card as shown. If you just can't get the solder to take, or your iron tip is too large to solder the lead with the circuit board in the battery tube, follow the alternate soldering instructions below. |
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Alternate Luxeon negative
lead soldering instructions
Remove the LED circuit card from the battery tube and secure it in a vise or clamp (light pressure!) so it won't move around while soldering. Observing the one second heat rule, solder the negative lead of the Luxeon to the top of the circuit card. Use solder wick to remove any excess solder from the edge of the circuit card where it makes contact with the battery tube lip. |
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Bend over and solder the
negative Luxeon lead to the GND section of the circuit board.
Do Not bend over the positive lead of the Luxeon. |
| Step 8. Soldering the Luxeon anode (positive lead) |
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Run a small piece of wire from the solder junction of the diode and capacitor to the Luxeon positive lead. Refer to the drawing for wire placement. |
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The wire should fit in the gap between the diode contact and body. |
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The wire should run between the diode and inductor, and connect to the positive lead of the Luxeon LED. Be sure the Luxeon positive lead is not touching the circuit board copper. |
| Step 9. Connecting the Contact Board and Pre-testing SMD |
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Solder a wire 3/4" long to
the contact board.
Form the solder into a low, smooth dome shape to make a nice + battery contact. |
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Connect the other end of the wire to the V IN section of the circuit board. This is best done by sharing the solder junction of the V IN and Inductor. |
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Carefully connect a test lead
from 2 AA cells negative contact to the SMD top or GND section of the
circuit card. Be careful the test clip does not short to any components or
other sections of the circuit card.
Connect a test lead lead from the 2 AA cells positive contact to the contact circuit board. The Luxeon LED should light up nice and bright. |
| Step 10. Final SMD Assembly |
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Pre-form the SMD as shown in
the photo. If the recommended wire has been used, its thickness when
routed on top of the inductor will make keeping the circuit boards
parallel very easy.
Carefully fold back the + contact board and apply a drop of 5 minute epoxy to the top of the inductor and diode. Do not use too much epoxy. If epoxy oozes out to the edges of the SMD it could end up being glued in the battery tube (bad). Fold the + contact board back on top of the inductor and diode as shown and insert into the battery tube. |
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Insert two AA cells and install the tail cap. Again, we don't want any electrons flowing, so insert the first battery backwards (negative end first) and second one normally (+ end first). |
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Now, monitor the left over epoxy you just mixed up. When it just sets up solid, remove the batteries and SMD from the battery tube (you may have to blow into the battery tube top to get the SMD to come out). Inspect the SMD for alignment. If it is leaning to one side, carefully straighten the contact board to be parallel with the LED circuit board. The epoxy should have enough elasticity still to allow the adjustment to be made. It may flex back out of alignment and you may have to repeat several times to get everything squared up. |
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Once the boards are aligned properly, back fill the inside of the SMD with thermal epoxy. Use a tooth pick to apply the epoxy, being careful not to apply too much. It's better to not apply enough and have to apply a second coat than applying too much. When the proper amount of epoxy is used, it should look like the SMD in the photo. Let the epoxy set up for 60 minutes minimum so it's good and hard. |
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Test fit the SMD into the
battery tube. Do not force it into the battery tube! If it does not slide
right in with no more than the weight of the batteries pushing it, file
the edges of the SMD down until it fits properly.
Your SMD is now completed and ready for service. |
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Unscrew the front bezel, remove the reflector and drop in the lens and then place the o-ring on top of it. Install the bezel (leave in the front window) and tighten. Drop the SMD in to the battery tube, Luxeon end first. Install 2 AA batteries and install the tail cap. The SMD should be lit up nice and bright. Screw on the head assembly and check for proper on/off operation. Wasn't that easy? |
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