Maglite bulb data

[cwithboat]

For the past few weeks I have searched for a viable source for a few sub-miniature bulbs for the aforementioned Sansui receiver. Closest part I could find was incandescent light bulb lamp, I 6V 0.05A WL T1 6.5MMMOL 15000H.
All this time a disassembled Maglite flashlight was sitting on my bench. A light (finally) went on (dummy). The Maglite bulb (LM3A001) was the perfect substitute...maybe. I have been unable to find engineering data for the Maglite lamp; Maximum voltage and current. Maglite info supplied on their website is quite limited. Any ideas for a source?

[BobSch]

Here's what I found through Google

ITEM NUMBER: S-LM3A001
DESCRIPTION: 1.5V .24A .36W T1 BI-PIN

[cwithboat]

Here's what I found through Google


ITEM NUMBER: S-LM3A001
DESCRIPTION: 1.5V .24A .36W T1 BI-PIN

Thanks, the info I got said 2 cell which would imply 3V, but the current looks to be close to what I surmised. I found some at the local hardware store, so I can hook them up and measure the impedance and the operation at 6V with a series resistor.

[eccentrictinkerer]

Maglite bulbs are often rated at a lower voltage than the battery voltage ie. 1.5 volt bulb in a 3 volt flashlight light. They do this to get a much brighter light.

The 1.5 volt bulb mentioned will put out four times the light when operated at 3 volts. My Panasonic 12 volt lantern uses 7.2 volt bulbs for the same reason, more light, at the sacrifice of some lamp life.

[cwithboat]

I hooked up the Maglite lamps I got at the hardware store. At 6 Volts I need a 24 Ohm resistor. at least 1 watt. to be safe 2 watts. they draw a bunch of current 200-300 mA. As soon as I find the resistors I will be set (and warm).

[gerti]

Sounds like a bad idea to me to try and drain 200-300 mA from a circuit designed to power a 50 mA bulb, not to mention the excess heat the resistor will generate.

Why not use a white LED with a matching resistor? Will pull 5-10mA and stay much cooler.

[cwithboat]

Sounds like a bad idea to me to try and drain 200-300 mA from a circuit designed to power a 50 mA bulb, not to mention the excess heat the resistor will generate.

Why not use a white LED with a matching resistor? Will pull 5-10mA and stay much cooler.

Test show you are correct. I was hoping that I could run the lamps at a lower level, but there is sharp turn on characteristic at 200mA. I will look into LEDs. The local Radio Shack just closed so I will have to go to Digikey.

[eccentrictinkerer]

Try a Google search for 'grain of wheat lamps' to find very small light bulbs. Surpus dealers have lots of them.

Also, try doll house accessories at your local craft store. I found some tiny low voltage lights for a recent project.

[Daryl]

Also maybe Christmas tree lights, they are small, you buy a new string or two every year instead of fixing an old one and you get a package of replacement bulbs with every new string.

[just started]

Model railroad layouts use them and so do ham radios.

[LCHIEN]

reading this thread gives me the willies.

1. xmas bulbs would be a seriously bad choice because they are designed to be run in series and short out when the filament goes bad to keep the other bulbs on. You don't want to short out your receivers power supply when the bulb goes out!

2. a flashlight bub is designed to illuminate a large area. The bulb in your receiver is meant to light up (probably, I'm assuming here) a panel or a small indicator or such function, the flashlight bulb would be way too bright.

3. sort of confirmed 2. given that the original bulb drew .05 amps and the flashlight bulb drew .240 amps at 1.5 or 3 volts (seems to be confusion there) but it would draw about 500 or more at 6V.

4. an incandescant bulb run at 2x or 4x the rated voltage would probably have a very short life. lifespan decreases exponentially with overvoltage.

5. LED sounds like a good idea, still guessing at the original function.

6. if you want an original bulb, you need to go someplace like this and identify the base style and size and then find the appropriate voltage and current (or wattage) which appears to be 6V and .05 amps from your original observation. The schematic shold also give mroe info, if you have it. Schematics are available widely on the net for old audio equipment.

http://www.topbulb.com/find/miniaturebulbs.asp

[cwithboat]

6. if you want an original bulb, you need to go someplace like this and identify the base style and size and then find the appropriate voltage and current (or wattage) which appears to be 6V and .05 amps from your original observation. The schematic shold also give mroe info, if you have it. Schematics are available widely on the net for old audio equipment.
http://www.topbulb.com/find/miniaturebulbs.asp

I checked several of these sites. The part I specified is available, I just don't need 100 of them or $40 worth. Note minimum orders.
I have a schematic and the maintenance manual, you have seen the info it gives (actually less because I did a lot of research before posting this). As for the function, it lights the dial pointer.
This thread has gotten entirely out of hand. I have more advice than I need.