Hi I am working on a project to mount a wireless camera onto an old train carrage. I want to use the power from the tracks to power the camera. The tracks are DCC and 15V so I have built a rectifier circuit and added a voltage regulator and everything works until the trian moves. When the train moves the camera goes off. It seems to be where the power is picked up by a small metal bush that rubs against the wheels, as the wheel turns it causes the current to flicker. Does anyone have any ideas on how i can over come this? I was think of something like a capacitor to supply power in the short time the power drops??? Any thoughts?

 

My first thought is the train is radically dropping the voltage when it is in motion. You need to measure this.

 

Many people use battery power for onboard cameras, due to the exact problem you are experiencing. A little more advanced approach is to use the track power to recharge the batteries.
You can ensure that your wheels are squeaky clean and the metal bushing is not worn down and that may imoprive your situation, but not eliminate it.
Another approach that will not solve all your problems is to place capacitors within the circuit, to bridge the gaps when power is interupted.

 

Yes, you need a capacitor. You'll also need a bridge rectifier, because the polarity of the rails may change as you move into different zones, particularly if you're operating more than one train at a time.

What is the current and voltage requirement of your camera?

 

And don't use a power rectifier made to work with a 60Hz input, because the diodes will be too slow to handle DCC. You'll probably have to build your own rectifier from 4 diodes--use "fast recovery" or Schottky diodes.