Adding led to engine?

[Llongfordrailway]

Hello,

I have a Roundhouse Little John and I'm looking to add a front LED headlight. There is a spare channel on the transmitter/receiver and I wondered whether it could be powered off this. It I suspect it wont be that simple.

Any advice or tips on this would be most helpful!

Regards

Daniel

 

[ge_rik]

Hi Daniel

If you're using Roundhouse's own LocoGlyde ESC, then it includes a circuit for directional lighting. According to their leaflet (http://www.roundhouse-eng.com/pdf/lesc.pdf), it looks as if you do not need to include a resistor, but I'd say it would be advisable to add one to the circuit to protect the LED. I'm sure there are others on the forum who'd advise on the resistance needed.

Rik

 

[nicebutdim]

If you are using any other receiver then you do have a 5v supply as long as you have a spare channel socket on the receiver. The red and black (or brown) leads of servos and escs are 5v supplied from the bec circuit. A 150 Ohm (I think) resister will be required but the led will be on all the time the receiver is powered.

 

[GAP]

I simply put my LEDs in parallel with the motor and use a resistor in series to limit the current, 20mA draw away from the motor has no effect on performance of a motor drawing about 500mA.
To get directional lighting I just fit them so that depending on the polarity one is biased off.
They only come on when the motor has voltage applied.
Might not be prototypical but the standard operating procedures (SOPs) on my rail way dictate the headlights are turned off when the loco is not in motion.
Well that's my story and I am sticking to it, rule 8 applies at all times on my railway.

 

[tramcar trev]

Yah like GAP says, but I cheat a little bit and put a big capacitor ( well a large capacity capacitor) and a diode in the circuit to keep the lights on for a while while the motor is stopped. These ones seem quite ok to use; http://www.jaycar.com.au/productView.asp?ID=RU6705  Depending on the current you allow your led to draw via the resistor decides how long the stays alight. You will need a diode though to stop the charged capacitor dumping its charge back into the motor. Because I always do things the hard way its easiest if you look here to see how I did it: