# Voltage Capacity for LGB 5v. Light Bulbs and Smoke Generators



## LGB333$$$$ (Oct 11, 2017)

FOR DAN PIERCE - Hi Dan, you're a DCC conversion installer like myself. I just completing an ESU 5XL DCC Sound Decoder installation into a customer's LGB Uintah Steamer and set the decoder's voltage output for the headlight and cab light at 6.2 volts. The lights didn't seem very bright while measuring the decoder's outputs under load on my Massoth DCC 20v. DCC Test Stand so I upped the voltage to the decoder's next setting: 7.2 volts and the lights are much brighter. Do you think using the 7.2 volts output to the 5 volts lights is detrimental to the normal longevity of the bulbs? Same question for the LGB 5 volts smoke generator using 7.2 volts to it under load?

I have tested the LGB 5v. light bulbs with DC voltage some months ago using up to 12 volts for a short time and they didn't burn out, but maybe 12 volts over time will diminish the light bulbs service life?

Your thoughts please.


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## piercedandan (9 mo ago)

My first question would be are you measuring peak voltage (assuming voltage is pulsed) or filtered DC voltage. This is where a ociliscope is handy. 12 volts will greatly shorten the bulb/smoke unit life. Note that a better way to control lights is to use the cl2N3 20 millamp regulator and use 20ma leds or 2 10ma leds in parallel. The cl2N3 is good for up to 90 volts DC so it is great for DC and DCC upgrades.


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## LGB333$$$$ (Oct 11, 2017)

piercedandan said:


> My first question would be are you measuring peak voltage (assuming voltage is pulsed) or filtered DC voltage. This is where a ociliscope is handy. 12 volts will greatly shorten the bulb/smoke unit life. Note that a better way to control lights is to use the cl2N3 20 millamp regulator and use 20ma leds or 2 10ma leds in parallel. The cl2N3 is good for up to 90 volts DC so it is great for DC and DCC upgrades.


I measure the decoder terminals output under load using my RRampMeter v4. unit which the producer says can accurately measure the decoder PWM voltage. I'm not using 12 volts, that was just a test. I also sent an inquiry to Massoth Germany on the lights and smoker voltage question and their reply is below. I decided to use 6 volts for the 5v. smoker and 7 volts for the lights for the current DCC sound decoder project I just completed and for my future decoder installs.

"You can operate the headlight and smoke generator at 7V. For the smoke generator, the voltage is specified between 4.5-6V DC. At higher voltages, the service life is shortened (even with the headlight), especially when it runs dry."

Thanks for your input!


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## krs (Feb 29, 2008)

LGB333$$$$ said:


> I measure the decoder terminals output under load using my RRampMeter v4. unit which the producer says can accurately measure the decoder PWM voltage. I'm not using 12 volts, that was just a test. I also sent an inquiry to Massoth Germany on the lights and smoker voltage question and their reply is below. I decided to use 6 volts for the 5v. smoker and 7 volts for the lights for the current DCC sound decoder project I just completed and for my future decoder installs.
> 
> "You can operate the headlight and smoke generator at 7V. For the smoke generator, the voltage is specified between 4.5-6V DC. At higher voltages, the service life is shortened (even with the headlight), especially when it runs dry."
> 
> Thanks for your input!


Let me throw in my 2 cents worth.
The key question, which Dan already asked, is the liht and smoke output of the ESU decoder a DC output or a PWM output with a variable duty cycle.
What voltage are you actually measuring with the RRampMeter vs the voltage setting of the ESU decoder.?
Years ago I looked at a schematic of the voltage regulator used by LGB to drive the "5-volt" incadescent bulbs, it was a very simple zener/transistor design with an output of 6.8 volts,sothis wouldbe the output voltage you should set the decoder to to get the same service life aswith the original LGB electronics.
But that only applies if the light output of the decoder is DC or filtered; if the decoder output is PWM this doesn't apply.
I would also strongly recommend, as Dan sugested as well, that you invest in an oscilloscope since you are doing these conversions as part of your business. Scopes are not that expensive and for the work you are doing,a pretty basic 2-channelscope would do.I think you should be able to claim that as a business expense.
With a scope you can see what the output voltage of the ESU decoder actually is, no guesswork.
And finally,I would look at using the LED lamp replacements that are currently available for the 5 volt bulbs use by LGB. The use the same mounting and havebuilt in current limiting.


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## piercedandan (9 mo ago)

One needs to remember that when bulbs were first used in the car industry that the lead acid batteries were 6.3 volts and later on 12.6 volts. The bulbs were made for the generator (now alternator) to have a slightly higher voltage output in order to charge the battery, so 6.3 batteries need 7 volts ans 1.6 volt batteries needed 14 volts. This did create a pseudo standard for low voltage lights which holds to this day. Old radios and TV's with tubes used 6.3 and 12.6 volt tubes!!


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## LGB333$$$$ (Oct 11, 2017)

krs said:


> Let me throw in my 2 cents worth.
> The key question, which Dan already asked, is the liht and smoke output of the ESU decoder a DC output or a PWM output with a variable duty cycle.
> What voltage are you actually measuring with the RRampMeter vs the voltage setting of the ESU decoder.?
> Years ago I looked at a schematic of the voltage regulator used by LGB to drive the "5-volt" incadescent bulbs, it was a very simple zener/transistor design with an output of 6.8 volts,sothis wouldbe the output voltage you should set the decoder to to get the same service life aswith the original LGB electronics.
> ...


Hi Knut - I'm pretty sure the ESU decoders output PWM just like the Massoth and Soundtraxx decoders do. I can only measure the output the lights and smoker are receiving under load from the ESU decoder. The ESU LokProgrammer provides adjustments to the terminals' output voltage on a range of 0 - 32. So, when I set the decoder's output for "3" it provides a 6.2 voltage output when powered by my Massoth DiMax 1210z Command Station set at 20 volts DCC to the track on my DCC Test Stand Track. Likewise, a LokProgrammer setting of "4" provides 7.2 output. So, as I mentioned, I settled on the 7.2 volts output for the lights and 6.2 volts output for the smoker, and these settings work well on the LGB 23881 Uintah Mallet Steamer locomotive DCC conversion I just completed. In fact, I've added a video of it operating on my test stand you can see and hear by going to my Website's Homepage, bottom of the page videos. The American steamer mallet chuff that ESU recorded it from is one of the best Mallet sounds I've heard, the Black Hills Central Railroad #110 BLW 2-6-6-2T articulated Mallet. Check it out at: LGB Trains | Old Dominion Railways | Repairs & DCC Installs | United States


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## piercedandan (9 mo ago)

One must remember that decoders like LGB have adjustable voltages for lights and smoke and the result is geared to the V+ value. I have a Zimo system that outputs 24 volts to the track, other systems like LGB only do 22 volts and NCE was less than 21 volts. This can make a big difference in smoke unit performance.


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