PDM

The Christmas Train Engine Lego Battery Box

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I have a kit of lights for the Lego Christmas Train.  The kit comes with a battery box.  So the lights are rated at around 4.5v. 

However this means that the train has to remain stationery (unless I bolt the additional battery box on board - unsightly). 

Fortunately the Christmas Train has a Lego engine and on board battery box.  Can I connect the lights to the secondary connection that the Lego battery box has so that they are on as the the train moves.  If so will the higher voltage kill the lights?  If not is there a cable for achieving the connection.

I welcome some advice.

Edited by PDM

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You can add another current limiting resistor in series to the LEDs account for the 9V.  Or maybe use a 5V voltage regulator such as a 7805. 

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Not sure what type of plug you have for your lights.  You could hide a small USB battery pack in the passenger car.  Then you could place the standard PF battery in the tender to power your train.  

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1 hour ago, PDM said:

Thanks for the replies.  I dornt know what a 7805 is nor where to get it?

Instead I have ordered a https://www.vonado.com/h-product-detail.html?goods_id=36771

Beware, that's simply a break-out adapter which will not reduce the voltage and could damage your lights.

A 7805 is an electronic component -- a voltage regulator that will 'step down' higher voltages to 5V. From both an ease-of-use and battery-life perspective, you might be better off with a 'buck' converter like this. Connect your vonado cable output to its input (cut off the red connector) and your LED lights to its output (cut off the white connector).

Edited by izx

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It looks like that adapter cable will lower the voltage but they don't tell you to what voltage in the product description. Maybe best to measure it with a multimeter before hooking up the LEDs.

 

Here is another way to power your own LEDs.  Pulling power from the Power Functions IR receiver.  The resistor value to use for LEDs can be calculated from here:  LED Series Resistor Calculator

39818721304_43c5ce8f57_c.jpgDo-It-Yourself LEGO LED Light by dr_spock_888, on Flickr

 

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