Ghost Repeller portable "eternal" light night

“Ghost Repeller” portable battery-powered night light / emergency light / anti Hypnagogia light

A “Ghost Repeller” is a dim and very unobtrusive portable night light. It is powered by 4x AA NiMH cells and will last for months and months, so you basically never turn it off. It can be used to light hallways or stairwells just enough to find you way around without switching on the lights. It is also nice for just enough lighting in tents, campers or other hideouts. Furthermore, in unknown surroundings (bed and breakfasts, hotel rooms, sleepovers, couch surfing etc) it can help you find your way around without waking everybody up. It has no lithium batteries, so it should be airtravel-friendly.

The Ghost Repeller uses a Dupont connector to easily equip 5 or 3 mm LEDs, a hook to mount it upside-down and storage for four additional LEDs in the cylinder part. If after a quarter to half a year the batteries run dry, they are easily changeable, since the Ghost Repeller is screwed (and not glued) together.

In the not-so-uncommon case that you are suffering from hallucinations in the phase of falling asleep ("Hypnagogia"), you may experience relief in having a very dim and unobtrusive night light. For additional hypnagogia information scroll down.

Materials

You will need

• soldering equipment for minimal soldering
• 1 small resistor (47 oder 56 Ohms)
• Dupont-connectors and crimping tools (use soldering if unavailable)
• a few centimeters of insulated wire
• 8 pieces of 12 x 12 mm AA battery contact plates
• 4 AA NiMH batteries
• a few drops of glue
• a bit of shrink tubing
• a single 5 mm LED (3 mm will work, too)
  • I found that warm white, cold white, color change RGB and simulated candlelight look the nicest

Printing

Print from PLA or PETG. If you want to use the Ghost Repeller upside-down using the hook, I recommend printing the bottom part and the hook from PETG. Print the diffusor from clear PLA or PETG. Hint: I found that if you print in PETG, print the emitter and the bottom part at 101 % scale because of PETG shrinkage. The threads will work much nicer.

The battery cage, the bottom part and the emitter will need supports. I strongly suggest you try paint-on organic supports which work so much nicer than the old ones. Once Prusaslicer 2.6.0 is released I will upload a 3mf file containing supports.

Assembly

Battery pack

Take 8 battery contact plates (4 positive, 4 negative) and bend the contact and bend all the little tabs 90 degrees downward. Stick the tab through the holes in the battery cage part. Here's the tricky part: Put 2 NiMH cells in series and put those two in parallel. Here's how:

On the bottom side put the tabs of the +/- pole next to each other. On the top side, put the tabs of the +/+ and -/- poles together. Use real cells so that the tabs are fixed in place. See the pictures for help.

Once you made sure your tabs are oriented correctly you can use a drop of glue on the base of the tab to fix the contact plate in place.

Next, solder the two +/- poles on the bottom side together. On the top side use a wire to contact the -/- poles. On the +/+ poles, use a wire with an additional resistor to limit the current. Use the shrink tubing to insulate the resistor. See the pictures for help.

Internal Parts

Glue the spacers to the battery cage. Notice that the upper spacer has a hole for the wiring. Make sure all 4 legs of the spacers are sitting flush inside their holes or the assembly will not fit inside the cylinder.

Emitter

We are using a Dupont connector for 3 wires as a fitting for the LED. Crimp two wires to fit the Dupont connector, see pictures for help. Notice that you might want to route the wires through the emitter part first before you assemble the connector. Use glue to fix the connector upright inside the emitter.

Final assembly

Screw the bottom part to the cylinder. Slide the battery pack inside the cylinder, connect the battery pack to the emitter and screw the emitter to the cylinder. Finally, for a nice look, screw the diffusor part on top of the emitter. 

Options

Of you printed the hook also, you can fit the hook in the bottom part. See pictures for help. The hook is nice for hanging the Ghost Repeller upside down in tents or campers. Also notice the cylinder has four holes. Use these to store additional LEDs. If you are using a Dupont connector, the LEDs are easily changeable.

Information on Hypnagogia

This project was inspired by YouTuber Big Clive's Episode on off-grid night lighting, check it out:

If you, your partner or your child are experiencing Hypnagogia and are hallucinating during the phase of falling asleep (see also Wikipedia), don't be alarmed: It's not that uncommon. Try a ghost repeller and sleep tight :-)