In the July 11th 2012 TVtechnology trade journal page 27, they have an article on bulb life vs applied voltage. Reducing applied voltage on a light bulb greatly extends life. Efficiency gets bad, but for pilot lights in radios, that's not much of a concern.

life/rated life = (rated voltage/applied voltage)^13.1

An example: In my Tasma Baby, I replaced the 6.3V pilot lights with bulbs rated for 7.2V, which will make them last 5 times longer.

Conversely, a light bulb run at 1.1 times its rated voltage will only last 20% of its rated life. So if your mains run a little high, and the pilot lights seem to burn out often, try using the 7.2V bulbs (intended for flashlights). The American chain Radio shack has them in stores, don't know if RS is in Australia, or similar store exists down under.

Or use a resistor to drop a volt from the 6.3V heater winding to run the bulb.

Good advice.

I recall once being told that the bulbs used in our traffic lights were rated at higher than our mains voltage (230/240 volts) in order to prolong their life. Nowadays, those traffic light bulbs are being replaced by LED arrays.

(And I think I've read somewhere that when they were in the 'off' state they were maintained at a voltage that was just under the incandescence voltage in order to minimise on/off mechanical wear from heating and cooling, again to prolong life)

We used to have Radio Shack stores here, branded as Tandy. But they were bought out by the supermarket chain that owns what was its competitor Dick Smith Electronics.

DSE has turned into essentially an appliance retailer so the only serious components, kits, etc, outlet around the country now is Jaycar, and to a lesser extent Altronics.

http://www.jaycar.com.au

http://www.altronics.com.au

Traffic signals used to be fitted with 260 volt lamps rated at 150 watts - these lamps were plentiful because that is what was sold in Western Australia for general use due to higher average voltages provided to households. Only difference was that the lamps in traffic signals had an ES base as opposed to the more commonplace bayonet cap.

Efficiency is not really an issue for incandescent lamps in most applications - at best around 8% of a lamp's power consumption is converted to light with the rest given off as heat.