6v pilot lamp

[UFO]

Trying to locate replacement bulbs for an old Wards / Airline transistor
radio, they are 6.3V
but only 20mA rated. Higher rated current lamps are out there, but in this
design they dim the bulb when you tune a station, so looks like they must be
that
rating, which also saves battery power.

I thought an 1175 lamp would do but the current is wrong. It has to be a T5
screw type
socket. Could not locate a bulb number for it...any ideas?

This is a pic. https://ibb.co/Bzxt7mb

The front bulb is what came out of the radio 6.3v 20mA. The back one is a
type 47, 6-8v 100mA way to big.

[jim whitby]

Post by UFO
Trying to locate replacement bulbs for an old Wards / Airline transistor
radio, they are 6.3V but only 20mA rated. Higher rated current lamps are
out there, but in this design they dim the bulb when you tune a station,
so looks like they must be that rating, which also saves battery power.
I thought an 1175 lamp would do but the current is wrong. It has to be a
T5 screw type socket. Could not locate a bulb number for it...any ideas?
This is a pic. https://ibb.co/Bzxt7mb
The front bulb is what came out of the radio 6.3v 20mA. The back one is
a type 47, 6-8v 100mA way to big.

Closest thing I could find.

Lamp # 342
6V AC/6V DC 0.2W 0.04A T1 3/4 blub

from
mcmaster.com/products/miniature-screw-base-light-bulbs/voltage~6v-ac/

[Sjouke Burry]

Post by UFO
Trying to locate replacement bulbs for an old Wards / Airline transistor
radio, they are 6.3V
but only 20mA rated. Higher rated current lamps are out there, but in this
design they dim the bulb when you tune a station, so looks like they must be
that
rating, which also saves battery power.
I thought an 1175 lamp would do but the current is wrong. It has to be a T5
screw type
socket. Could not locate a bulb number for it...any ideas?
This is a pic. https://ibb.co/Bzxt7mb
The front bulb is what came out of the radio 6.3v 20mA. The back one is a
type 47, 6-8v 100mA way to big.

I replaced two of those fm stereo tuning
lamps with two red leds.
Still working after 20 years.........

[ehsjr]

Post by UFO
Trying to locate replacement bulbs for an old Wards / Airline transistor
radio, they are 6.3V
but only 20mA rated. Higher rated current lamps are out there, but in this
design they dim the bulb when you tune a station, so looks like they
must be that
rating, which also saves battery power.
I thought an 1175 lamp would do but the current is wrong. It has to be a T5
screw type
socket. Could not locate a bulb number for it...any ideas?
This is a pic.  https://ibb.co/Bzxt7mb
The front bulb is what came out of the radio 6.3v 20mA. The back one is a
type 47, 6-8v 100mA way to big.

Might be time to consider replacing the bulb with
an LED and series current limiting resistor. The
mechanical part - mounting the LED - might be a little
challenging, but determining the resistor size is
straight forward. If you're not sure of that, we can
help you here.

Ed

[UFO]

Been hearing that a lot for responses.
Since the LED needs I guess 1.5V to be on,
and can burn out with too much voltage, it
did not seem to be a suitable option.

[Arie de Muijnck]

Post by UFO
Been hearing that a lot for responses.
Since the LED needs I guess 1.5V to be on,
and can burn out with too much voltage, it
did not seem to be a suitable option.

That is why series resistors are always used.
R = (Vin - Vled) / Iled

Arie

[ehsjr]

Post by UFO
Been hearing that a lot for responses.
Since the LED needs I guess 1.5V to be on,
and can burn out with too much voltage, it
did not seem to be a suitable option.

Here's a diagram:

+6V ---resistor---LED---ground

Assuming a red LED you need roughly 1.5 volts
applied to it. That means the resistor has to
drop about 4.5 volts. We want the current to
be 20 mA or less, so we'll choose 10 mA. The
formula to determine the resistance is R=E/I
where E is the voltage to be dropped and I is
the current through the LED. So R = 4.5/.010
That equals 450 ohms, and the closest standard
value is 470 ohms, which will work just fine.
A 1/8 watt resistor is the smallest trough hole
size and may be easier to fit in than a 1/4 watt.
It depends on what you have on hand that will physically
fit - the resistor will use only about .05 watt

The current through the LED does not have to
be exact - anything from say 2ma (often much
lower, depending on the LED) to 20mA will light
it up nicely. If you want to use a white LED
you can. A white LED needs roughly 3.2 volts
so the resistor value changes to roughly 280 ohms,
which means using a 270 or 330 ohm standard size.
I'd use 330.

Ed

[legg]

Post by UFO
Trying to locate replacement bulbs for an old Wards / Airline transistor
radio, they are 6.3V
but only 20mA rated. Higher rated current lamps are out there, but in this
design they dim the bulb when you tune a station, so looks like they must be
that
rating, which also saves battery power.
I thought an 1175 lamp would do but the current is wrong. It has to be a T5
screw type
socket. Could not locate a bulb number for it...any ideas?
This is a pic. https://ibb.co/Bzxt7mb
The front bulb is what came out of the radio 6.3v 20mA. The back one is a
type 47, 6-8v 100mA way to big.

Used to be a common part for analog meter illumination, so keep
looking. Was once a radio shack number.

RL

[UFO]

Yes, Radio shack # 272-1140

https://www.ebay.com/itm/325945990509

No longer availabe.

Post by legg
Used to be a common part for analog meter illumination, so keep
looking. Was once a radio shack number.
RL