# LGB 20215 Christmas Stainz - Massoth DCC Sound Conversion



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

FOR DAN PIERCE - I recall that you converted a customer's LGB 20215 to a Zimo sound decoder last year. I'm using a Massoth LS sound decoder to replace the factory electronics. I note on the existing circuit board a small additional circuit board that powers the locomotive's front lighted Christmas tree. What does that circuit board do for the lighted tree: I measured the input to that board at 6.3 volts and output to the tree at 17 volts? Should I reuse that circuit board on the output of the Massoth decoder's terminal to the tree? 
Thanks
Tom


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## Dan Pierce (Jan 2, 2008)

That board is just a converter to create 17 volts from any input (usually 5 volts or more), a must for DC operations. Just tie 17 volts to the christmas tree wires. You can measure the decoder V+ on your power supply and just use a resistor to drop the voltage to 17 volts or less after you measure the current the lights draw.


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

Dan Pierce said:


> That board is just a converter to create 17 volts from any input (usually 5 volts or more), a must for DC operations. Just tie 17 volts to the christmas tree wires. You can measure the decoder V+ on your power supply and just use a resistor to drop the voltage to 17 volts or less after you measure the current the lights draw.


Thanks, Dan, appreciate your reply. Since I'm converting the Stainz to a Massoth LS DCC Sound Decoder, I can adjust the voltage output to 17 volts to the Christmas tree light string on the decoder's output terminal.

I'm curious, would that converter board also handle DCC current to boost the voltage to 17 volts or will it only handle DC current?


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## Greg Elmassian (Jan 3, 2008)

That sure looks like a full wave bridge on the input.... that would seem to answer that question...


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## Dan Pierce (Jan 2, 2008)

Many decoders use a pulsed power to average a voltage. This is great for regular bulbs and motors, but not for electronic devices such as IC chips and leds as they see the total voltage not the average. This is why I suggested a resistor from V+.


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## Greg Elmassian (Jan 3, 2008)

With a full wave bridge on DCC as power input, the output needs little if any filtering to get reasonable DC output. Remember it's basically a symmetric square wave, not the sinusoidal AC that does indeed need filtering after a FW bridge.

So I would verify the power input indeed goes through that FW bridge, and also the max input voltage of that board. 

Greg


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