Bardic Lamps

This little chap is a Bardic signalling lamp. It's an ex-British Rail lamp that I use for showing signals while I am working on the railway in the dark. It shows red, white or green lights - there are versions which will show yellow light as well, but since I am not a guard I don't need one of those.

Bardics are cast aluminium lamps which are really quite robust - I use mine for all sorts of jobs on evening turns.

This is the unit that carries the switch and colour aspects inside the lamp. It's held to the lamp casting by three self tapping screws:

Inside the main body casting is a register which limits the movement of the switch:

It mates with this brass pressing, which moves with the switch spindle. It's set up to allow the switch to select three positions and it prevents the yellow aspect being used on this lamp.

It's useful to put a smear of silicone grease on this part, along with the brass detent wheel and the switch spindle. You often have to use these things in a hurry, and freeing up the mechanism helps no end.

Here's the bulb holder, which normally carries a P13.5S lantern bulb, rated 3.5 V, 0.3 W.

You can also see the switch, which is operated by a shaped sphere on the end of the spindle. You push the spindle downwards to turn the lamp on.

This is the standard AD28 battery used by Bardic lamps, three 1.5 V cells wired to a two pin socket at one end. Unfortunately, these are not available any more:

An option is to use one of these. These plastic battery cases are available in a wide variety of sizes,, and this version using three D cells fits inside the Bardic. These things cost about a fiver and D cells are £1-£3 each.

As anyone who has read my motorcycle blog will know, I'm a big fan of these VRLA sealed lead acid batteries. They are cheap, and you can fit them in any orientation. This one is a NP1.3-6, which means it is a 1.3 Ah battery at 6V. That capacity would give us 6 x 1.3 x 0.5 = 3.9W for an hour, or a watt for 3.9 hours exhausting the battery to 50%, which is enough if you don't want to kill your battery prematurely. These are about £8, and you can get two in a Bardic if you need to.

This is a 0.5W, 6V P13.5S CREE LED, giving about 50 lumens - perfect for our needs, and that will allow the battery to last 7.8 hours to 50% capacity. It's plenty bright enough, but it does wash out the colours.

I've installed the battery in the lamp using heavy duty Velcro - this is self adhesive and you will need a plastic ruler or similar to get it apart.

I'm charging it using my 6V CTEK battery charger, by attaching the crocodile clips directly to the battery terminals with the lamp open. I may installed a charging connector at some point.

For anyone looking for a replacement knob, the spindle is 4.6 mm diameter.

The knob is retained with an M2 screw, 6 mm long.