DIY MiniPro Light Engine Kit

Operates from 1 or 2 AA cells NiMh/NiCd, alkaline or lithium

Drop in switch / bulb socket replacement light engine upgrade for popular AA size flashlights

Get the MiniPro light engine today and transform your 2AA flashlight into a light with the brightness and performance of much larger flashlights. 

The MiniPro also has a low level survival mode so when the batteries do run down you won't be left in the dark. The low level light is sufficient to navigate in a dark area while you get some fresh batteries. 

TWOH 3 Watt Luxeon LED Emitter
AA Heatsink and micro screw - $5.00
Glass Lens & custom reflector - $5.00
MiniPro Converter Kit - $12.00
Converter kit component parts:
IC - $5.00
X5R Capacitor - $2.00 (two required)
Inductor - $3.00
PCB - $2.00

Go slowly and check the fit of the board into the rear of the heatsink.

DO NOT file too much! 

Use a fine tooth file or emery board. File just enough to remove any rough material and bring it to the edge of the copper plating so the board fits snugly into the heatsink.  Now clean the copper on the converter circuit board with an eraser or paper towel and alcohol. 

TIP: Clean copper solders much easier

This step is just to ensure there are no microscopic copper hairs left behind after the etching process. It is very rare to find a short, but checking the board now eliminates it from any future possible troubleshooting that may be required.

General guidance - Do not apply too much heat. Electrical components can be damaged by excessive heat during soldering. It is recommended that you use the three count rule when soldering surface mount components. The three count rule is that during soldering, begin counting to three when you apply heat and remove the soldering iron when the count of three is reached (approx 2-3 seconds), even if the soldering operation is not complete. Let things cool back down and re-solder the joint if not accomplished the first time, again using the three count rule. Surface mount components will generally need to be held in position during soldering as the surface tension of the solder paste as it melts in to liquid solder can pull the components out of position.

For the following steps it is recommended that the circuit board be mounted in a vise or other similar device to hold it stationary during soldering. As a general good practice, test fit components on the circuit board before adding soldering paste to insure proper alignment.

Note: Although references in the instructions relate to solder paste, fine gauge solder (0.015 inch or smaller recommended) can be used in it's place.

This step is important to complete before trying to solder the components on the other side of the board. Heat generated when soldering this large contact area could cause components to unsolder from the other side of the board if not done first.

Position the IC on the circuit board as shown in the next couple drawings. 

The IC will need to be held in position when soldered or it will move. 

Don't sweat it if you do get some solder on the contact ring area, it can be cleaned up with solder wick and alcohol later. 

It may be necessary to re-align the IC after applying the solder paste. Solder Pin 4 by placing the tip of your soldering iron on the copper right next to the pin. Observe the solder paste and continue heating until it all has melted and flowed; remove heat immediately. This will anchor the IC in place so the rest of the leads can be soldered.

Do not allow capacitor to stick out past the edge of the etched circle. Keep it within the edges of the etched ring on the circuit board.

You will need to hold the capacitor in place during soldering or it may move out of position. Apply a small amount of solder paste and apply heat using the three count rule. 

Do not allow capacitor to stick out past the edge of the etched circle. Keep it within the edges of the etched ring on the circuit board.

Do not allow inductor to stick out past the edge of the etched circle. Keep it within the edges of the etched ring on the circuit board.

Solder one wire to the ground connection as shown in the photo. 

The completed converter should like the sample in the photo. 

Slide the insulator over the Vout  lead of the converter as shown in the photo. This will keep the Vout wire from shorting to the heatsink. 

Be sure the insulation is below the top surface of the heatsink when test fitting the converter to the heatsink. Trim any excess insulation length and re-install on the Vout wire and test fit again on the heatsink. 

Note the ground is common to both input and output; (connect the Luxeon negative and battery ground together). 

If the converter does not work properly, then inspect for solder bridges between pins and between copper circuit patterns. If solder bridges are found, use solder wick to carefully remove. Once proper operation of the converter is verified, continue on to step 4.

Insert the converter board into the heatsink. Carefully guide the positive output wire with the insulation into the hole of the heatsink (the side with one hole). The ground wire goes into the hole opposite the single hole.

Check to see that the screw hole in the circuit board aligns with the screw hole in the heatsink. Adjust the circuit board by rotating left or right until the screw holes align.  

Verify electrical operation again. 

Use solder wick to remove any solder still remaining between the lead and circuit board.

Grip 90 degrees from the leads so they are not damaged.

Note that there are studs next to the leads. The lead with the longer stud is the positive lead that will get connected to Vout.

The face of the heatsink has a precision cut out for the Luxeon stud. It will perfectly center the Luxeon and provide for maximum heat transfer. Mix a small amount of thermal epoxy and apply a thin layer to the cut out in the heatsink. Carefully position the Luxeon (Note Polarity) and press down firmly on the Luxeon case to sqeeze out excess epoxy. You want the thermal epoxy to be as thin a layer as possible for good heat conduction. 

Do not push on the Luxeon lens, as this can cause bubbles in the lens. Push only on the black case around the lens, not the lens itself. 

Replace the plastic lens and reflector with the supplied glass front window and reflector and install the bezel ring back onto the head. 

Fine adjustment can be made to the Luxeon centering in the reflector by rotating through the four sets of threads cut in the MiniMag. To do so, simply keep some downward pressure on the flashlight head as you unscrew it. Once the end of the threads are reached, you will feel and hear a click as the head rotates to next set of threads. When you feel the click, tighten the head back down and check beam centering. Repeat as necessary to find which of the four sets of threads gives the best beam. You may also rotate the MiniPro pill a few degrees in combination with the different threads to fine tune the beam to be perfectly centered.

Unlike other more complex, and less performing converters, this circuit needs only four active components; IC, Inductor, Input Capacitor and Output Capacitor. The circuit works very well on just one AA cell driving a Luxeon LED for a very small and bright flashlight. Two cells can be used for super bright output. 

While the MiniPro is not a current regulating circuit, it is quite evident from the runtime graphs that it achieves the same or better regulation results as current regulated circuits when driving a Luxeon LED.

The MAX1797 has a preset, pin-selectable (Pin 2) 5V or 3.3V output. The output can also be adjusted to other voltages, using just two external resistors or a single potentiometer. Future converter only versions of this circuit will take advantage of these features for custom applications.

Further information and performance details of the MAX1797 can be found on the Maxim web site.