A small board used to easily limit current in standard RC LED strings that use JST-PH connectors.
You can choose to use a standard ¼ watt through-hole resistor of any value, or a current-limiting IC such as the Diodes Inc AL5809 (typical choices might be 20mA or 40mA).
Use a JST-PH pigtail for the voltage input, and plug it into your light controller. Search eBay for “JST PH 2 pin connector.”
For the output you can use a right-angle JST-PH connector (JST Part No.
S2B-PH-K-S), or you can use the large solder pads on both the top and bottom of the board to solder LEDs or wire directly to the board.
The bottom of the board is entirely white silkscreen for writing a small note with a fine-tipped Sharpie - such as the resistor value, so you don’t forget.
Use clear heatshrink when done assembling. Heatshrink that is approximately ¾" (18-20mm) wide when laid flat works well.
See the Accessories page of the Open Panzer TCB wiki for some photos, or this post on the Open Source RC Lights thread.