taped it to the front panel aluminum. I center-punched all
locations of the holes, drilled the holes, and used a nibbler
to cut out the square for the display slightly larger than the
blue display border. Finally, I carefully epoxied the locking
wire for the module to the front panel.
To prepare the front panel, print the front panel
artwork (available at the article link) on nice quality photo
paper. Using an X-Acto™ knife, cut out the square for the
display leaving the blue border. Put a clear cover sheet over
your artwork using Avery Clear Full-Sheet Labels (#8665),
for example, then apply an Aleene’s Tacky Double-Stick
Sheet to the rear of the front panel artwork.
Prepare a red transparency the size of the aluminum
display opening. Carefully trim the outside of the front
panel artwork, remove the backing paper, and apply it to
the aluminum front panel. The red transparency can now
be placed in the hole of the aluminum front panel and it
will stick to the backside of the display artwork. Before
mounting the display, we must change the voltage indicator
from a “U” to a “V.” To do this, place two small triangles of
black electrical tape on the display as shown in Figure 12.
Now for final assembly. Mount all of the front panel
components including the CV/CI module as shown in
Figure 13. Mount all of the components inside the box that
includes the fan, 5V regulator (for the fan), 7.2V regulator,
and power entry connector, also shown in Figure 13.
Wire the pots to the CV/CI module as in Figure 14.
The two outside solder pads of the voltage pot are
connected together, so only two wires to the pot are
needed: one to CCW (pin 1) and one to the tap (pin 2).
The wire wound potentiometer pinouts are as follows: 1 =
CCW; 2 = Slider; and 3 = CW. When wiring the constant
current LED, be very careful with the + and - as a wiring
error here will cause death of the switching regulator
XL4005 when the power supply is supposed to go into
current limiting. I would recommend that you use your
VOM to check the wiring.
Do you want your masterpiece to last? Broken wires
are a major cause of early mortality of your home-built
circuit. To prevent these wires from breaking, add a little
hot melt glue over the ends of the wire to cover the
insulation to the bare solder joint; refer again to Figure 14.
This also needs to be done at the other end where the wire
connects to terminals or components such as the LEDs.
Start out with the power off by turning the voltage and
amperage knob completely counter-clockwise; then, go up
about two full turns. Before powering up your power
supply, check the wiring. Turn the pot counter-clockwise on
the LM2596S DC-DC buck converter module.
You are now ready to power-up the module. Plug in
your HP 0957-2093 supply and set the trim pot of the
LM2596S DC-DC buck converter for an output voltage of
7.2V. The CV/CI power supply should now be displaying a
voltage of about 6.5V and 0A. You should be able to set
the voltage between .8V and 30V.
Do not short out your power supply to set the current
limit with the power on as this could blow your XL4005
from the sparks. (I think Nikola Tesla and Guglielmo
30 May 2014
; FIGURE 10. CV/CI module mounting wires.
; FIGURE 9.