Power supply

 
  donatchud Beginner

Hi
I have an inertia type (DC) power supply which is now approx 15 years old, it still works and until recently been very happy with it. I have just set up a small oval as a test track with a cheap $15 power supply. With the inertia power controller i get a buzzing sound from the loco as soon as i turn the power on which increases as the power increases, with the cheap controller no noise at all. Unsure if the buzzing has always been there or that i have become accustomed to it. WHAT IS HAPPENING? DO I HAVE A PROBLEM?

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  apw5910 Deputy Commissioner

Location: Location: Location.
If you haven't let the smoke out, there's probably nothing to worry about. You've just gotten used to the inertia controller.

Some (not all) inertia controllers use a square wave to drive the motor - the ON part of the square wave supplies power that turns the motor. In the OFF part the motor is still turning and is a generator. This allows the controller to sense the voltage being generated which is proportional to the load the motor is having. This allows feedback to alter the length of the the next ON pulse to keep the train moving at a constant rate (or accelerate/slow down smoothly). AKA pulse width modulation (PWM). "Chopper controlled" real interurbans like V-sets in NSW use this, too.

The cheap controller is probably providing constant DC which doesn't have the pulses that are causing the motor to buzz.
  donatchud Beginner

If you haven't let the smoke out, there's probably nothing to worry about. You've just gotten used to the inertia controller.

Some (not all) inertia controllers use a square wave to drive the motor - the ON part of the square wave supplies power that turns the motor. In the OFF part the motor is still turning and is a generator. This allows the controller to sense the voltage being generated which is proportional to the load the motor is having. This allows feedback to alter the length of the the next ON pulse to keep the train moving at a constant rate (or accelerate/slow down smoothly). AKA pulse width modulation (PWM). "Chopper controlled" real interurbans like V-sets in NSW use this, too.

The cheap controller is probably providing constant DC which doesn't have the pulses that are causing the motor to buzz.
apw5910
Thanks

The pulses causing the buzzing is part of the control system and i assume it is not causing any damage.

Cheers

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