Are Resistors Needed?


I am doing a custom install in a LEGO MOC locomotive.  I am using a PF rechargeable battery box for power.  I am using a Model Rectifier Corp Loco Genie DC/DCC board for motor, sound, and light control.  I will have 8 Brickstuff warm white LED's, 4 for forward, and 4 for reverse.  The Loco Genie board has directional control for the lights.  The Loco Genie paperwork says to install 750 ohm resistors if using 1.5v LEDs.  The PF Rechargeable battery box is set to full voltage ~7.4v to allow the Loco Genie board to have full power for motor, sound, and light control.  Do I need to add resistors between the Loco Genie light output, and the Brickstuff LEDs?


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    • Josh
    • Josh
    • 2 yrs ago
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    Brickstuff Picos have a resistor onboard already, but these are for 5 volt systems. If you want to be safe, you could add an extra ~120 ohm resistor.

  • Thanks, Sal , for your question.  Josh has it right-- add an extra resistor and you should be good.  Make sure to share photos with the rest of us when you have things up & running!

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  • Thank you both for the quick answers. Just to make sure, this resistor world be suitable to wire between the Loco Genie output and 4 LEDs?



  • Sal Ciofani Sure, or you could get away with an even smaller/less expensive resistor:

  • Rob Klingberg Thank you, there were a lot of 120 ohm resistors, and it has been way too long since I took a Solid State Electronics class.  I am definitely not as well versed in resistors as I probably should be for some projects like these.   

  • Sal Ciofani I'll tell you a secret: I've never once taken an Electronics class.  😉  It's all trial and error as far as I'm concerned-- thankfully these parts are so much less expensive and more widely available then when I was experimenting as a kid back in the 70s!

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  • 2 yrs agoLast active
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