Supply #47 6.3V bulb with 9V DC?

[disorder]

Could I get away with lighting up a #47 bulb (6.3V) using a 9V supply and 3V zener? Trying to use a tube amp bulb in a pedal in a pinch .

[Seljer]

Seems alright to me Incandescent bulbs aren't to fussy about voltage, it might shine a little brighter/dimmer if the voltage is off, but you'll get the added (dis)advantage of shorter/longer lifetime.

A quick search says it need 0.15A. 0.15A * 3V drop over the zener = 0.45W power being dissipated, so use at least a 1/2 watt zener diode.

[PRR]

Use a resistor.

Aim for like 5V. (Life of #47 is short on 6V; and modern #47s are not what they used to be.)

9V-5V= 4V to lose.

#47 is nominal 0.150 Amps.

4V/0.150A = 27 Ohms

4V*0.150A = 0.6 Watts

Try two 47-Ohm 1/2W in parallel to each other, series with lamp.

Note that 0.150 Amps, 150mA, is a LOT of current by pedal standards.

[davent]

With an LED you could get away with well under one mA to power the  indicator light, saves a lot on batteries.