This page shows how I modified my Rayovac Sportsman 3-in-1 headlamp to use three
bright white LEDs, instead of a single white LED and two red LEDs.
The first thing I did was to design and build the constant current
circuit. Well, ok, I didn't design the whole thing; I looked all over the
internet for the circuit design, and found one that is used often in a lot of
applications, then modified it to meet my specifications. What I needed
was a circuit that would feed 20mA to three LEDs for as long as possible,
regardless of the batteries' state of charge. What I designed does the trick rather
well.
Finally, I modified the lamp using the new board and Nichia white LEDs. I will list the
steps I followed as instructions, in case someone out there wants to convert
their own Rayovac 3-in-1.
Remove the battery pack, then remove the krypton bulb's lens cap by
unscrewing it from the unit.
Remove the krypton bulb, then the three screws that hold the black
front plate onto the base
Pull the PCB off the front plate. Here's the
original PCB:
Figure 1 - Component Side
Figure 2 - Solder Side
Figure 3 - Sketch of Circuit Paths
with Locations of Daughterboard Connections (shaded runs are on
solder side)
With the original PCB out:
Remove the three resistors.
Unsolder and partially lift the black, quarter-moon shaped battery contact
assembly so
that you can reach the first LED's leads.
Remove the three LEDs.
Solder on the new white LEDs, minding the polarity. I used 3 Nichia
8000mcd LEDs I bought from Paul
Wilcoxson for $1.75 each.
Push the battery contact assembly back onto the PCB and re-solder its
contacts.
Wire the new daughterboard to the original PCB by soldering its wires as
shown in figure 3 above.
The daughterboard's Vin wire pokes through the rivet hole from the
component side, and is soldered to the original soldering point on the solder
side (see figure 4, below).
Solder the DB's LED- to one of the solder pads where the positive end
of a resistor was. Then, using a clipped lead wire from one of the
LEDs you just used, solder together all three resistor solder pads on
the positive end. (See figure 5, below)
The DB's ground wire pokes through an empty hole where Rayovac
intended a diode to go. When you strip the end of the wire, leave
it long enough to reach over to the other diode solder pad. See figure
4, below.
Insert the daughterboard into the cavity behind where the original PCB is
mounted (figure 6), then replace the original PCB. Don't
replace the empty rubber cylinder (for a spare halogen bulb?) because it
won't fit with the daughterboard in place.
Replace the black front plate and screw it on.
Replace the krypton bulb, then put the lens cap back on.
Replace the battery pack.
Turn it on!
One consequence of this mod is that both of the switch positions for the LED
turn on all three LEDs, where before position 1 turned on the single white LED,
and position 2 turned on the two red LEDs.
