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Walthers 933-2310 tear drop lamp specs

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  • Member since
    June, 2007
  • 196 posts
Walthers 933-2310 tear drop lamp specs
Posted by Reformed Grownup on Sunday, March 19, 2017 10:15 AM

I added on to my diesel shop and I am getting ready to wire it up. The meager instruction sheet only mentions that it can be powered by ac or dc power up to 12v. I am planning to power it from the same decoder that runs my turntable motor, but need to know the resistor value to drop the voltage to below 12v. Without the lamp specs I can't calculate the resistor. I don't have a multimeter to measure it directly. Does anyone know the appropriate amperage for this lamp? Thanks in advance. Richard

Richard
  • Member since
    December, 2004
  • From: Bedford, MA, USA
  • 17,256 posts
Posted by MisterBeasley on Sunday, March 19, 2017 11:08 AM

The best advice I can give is "Go to Harbor Freight and buy a meter."

These small bulbs typically need about 30-40 milliamps.  I would probably run them at 9v to save bulb life and dim them down a bit.

It takes an iron man to play with a toy iron horse. 

  • Member since
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  • From: Collinwood, Ohio, USA
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Posted by gmpullman on Sunday, March 19, 2017 11:09 AM

Hi, Richard.

I just measured the one spare 2310 lamp I have.

12VDC = 24 mA The lamp is fairly dim at this voltage. Probably last much longer, though.

I did check at 14VDC and got 27 mA using a lab power supply.

Hope that helps, Ed

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Posted by Reformed Grownup on Sunday, March 19, 2017 7:01 PM

Thanks to both of you for your assistance !

Richard
  • Member since
    June, 2007
  • 196 posts
Posted by Reformed Grownup on Monday, March 20, 2017 11:37 AM

Just to put a ribbon on the topic, here is the official reply from Walther's customer Service:

'Good Morning Richard,

The new number for the item you have is 949-4319; same set of lights, new
number. Each bulb draws 25mA @12volts.

Regards,
Gregg Volke
Walthers Parts & Warranty"

 

Thanks again to those that chimed in.

Richard

Richard
  • Member since
    March, 2017
  • 34 posts
Posted by Canalligators on Wednesday, March 22, 2017 9:20 AM

Another approach is to guess very low on the current (high on the resistor) and swap in lower resistance values until you're pleased with the output and it's obviously not burning super bright.  That only works if you've got a stash of resistors around, though.

But I second buying a meter.  I don't know how you can be in this hobby without one.  Even the inexpensive ones are as good or better than a lab meter from years ago - for $10!

Genesee Terminal, freelanced HO in Upstate NY

...hosting Loon Bay Transit Authority

CP/D&H, N scale somewhere on the Canadian Shield

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  • From: Pa.
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Posted by DigitalGriffin on Wednesday, March 22, 2017 10:34 AM

Use a couple of diodes.  They are cheap and each one drops the voltage 0.7V->1.0V (typical).  This is specified as the forward voltage (Vf) on most spec sheets.

So if you put 3 in a series you have a gaurenteed 2.1V drop.  12 - 2.1 = 9.9V

https://www.allaboutcircuits.com/textbook/semiconductors/chpt-3/introduction-to-diodes-and-rectifiers/

 

Don - Specializing in layout DC->DCC conversions

Modeling C&O transition era and steel industries There's Nothing Like Big Steam!

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