A 'Trench Art' Electronic Candle

This project is my attempt to imitate with modern means a lighter made of a cartridge shell by a soldier of the past. Such lighters are very present in the Trench Art (see the link); my electronic candle is, therefore, inspired by one of them.

https://www.iwm.org.uk/history/beauty-from-the-battlefield-10-pieces-of-trench-art

Materials

- sheet copper 0.7 mm thick

- plastic gun sticks (diameter 7 mm)

- a piece of wood or plywood 10 mm thick

- a piece plastic 2 mm thick

- solder

Tools

- a pair of scissors for metal

- file

- drill with drilling bits

- soldering gun

- glue gun

hammer exacto knife a pair of wire cutters fine saw

Components

- one amber flickering LED

- current limiter

- miniature on-off switch

- two batteries LR44

- wires

The LED and the limiter are bought at Lighthouse Leds (lighthouseleds.com)

The ‘flame’ is made of a glue gun stick; that’s how I manufactured them:

- hold an end of the stick over the flame of a candle

- when plastic begins to melt and flow, remove the stick from the flame

- wait until the plastic solidifies; you might need to cut periodically the ‘thread’ which is being formed to avoid that the ‘top of the flame’ becomes too thick, see fig. 1

- cut the ‘flame’ as shown in fig. 2

- fix the piece in the holder shown in fig. 3

- drill a 5 mm diameter* hole, 8 mm deep in the bottom of the piece; this is the place for the LED

make a chamfer around the rims of the bottom’s hole to make it look more similar to a small ‘flame’, see fig. 4

I began drilling with a 2 mm bit to ensure that the hole is well positioned in the stick’s centre; then I continued drilling with 3.5 mm and 5 mm bits. However, the elastic walls of the piece ‘make way’ to the 5 mm bit, so it doesn’t cut enough material to produce a 5 mm hole; I repeated the drilling with a 5.5 mm bit and managed to get a slightly tight fit of the ‘flame’ on the LED. The ‘flame’ should be installed easily on the LED.

An amber flickering LED is used to ‘light the flame’; the circuit is shown in fig. 5. R1 is a current limiter that maintains the current in the circuit equal to 20 mA independently of the applied voltage (provided this voltage is bigger that is strictly necessary to power the LED, 2.1 volts for an amber LED).

The source of power is composed of two LR44 batteries placed in a DIY holder made of transparent plastic, see figs. 6, 7 and 8; the contacts are made of a thin (about 0.2 mm) copper stripe.

The ‘case’ is made of copper sheet according to fig. 1. The tubes are formed on wooden or metallic rods of respective diameters, I used metallic rods 10 mm and 15 mm in diameter available at my workshop. The inner diameter of the case’s bigger part should be sufficient to accommodate the batteries. Fig.2 shows how to fix the tubes and the conical part while soldering; fig. 3 shows the flat pattern of the conical part. Figs. 4 and 5 show the fixture which I used to solder the case’s parts together.

The case’s bottom is also made of sheet copper, see fig. 6; this part will be glued to the wooden socket.

The LED is installed in the top ring (see fig. 7); this ring is made of copper sheet and filled with molten plastic. After the plastic solidifies, the holes should be made as shown in fig. 8.

The socket (see fig. 9) is made of a standard wooden piece for furniture, its diameter is 30 mm, its thickness is 10 mm; there’s a groove in the socket’s bottom to place the switch. After the case’s bottom is glued to the socket, the latter will be varnished.