[Ryan]

Hello,

I've got a few questions:

1. Hornby loco's are made for 12 Volt, and Fleischmann analogous use's 14 Volts, but my loco's drive on 14 Volts, but is that a problem, or will I maybe get problems in the future?

2. I'm looking for a digital system from Hornby or Bachmann. (Or a other brand) It must be easy to use, and it must be possible to let some trains driving in different directions. (Select train One, select a speed, so he drives from A to B, en then select train Two, and drive from B to A.) And it musn't cost to much.

3. I'm looking for a train Unit, with some detail, but I can't choose one, and I only know Hornby and Bachmann as brand, are there any more brand's? (It must me a finished model, not a kit)

Thanks for your cooperation.

 

[dwb]

A full answer to question 1 is rather long and complex. For "traditional" variable resistance controllers, supplying 14 volts instead of 12 probably doesn't make a lot difference because the voltage applied to the track is only half wave rectified in any case, so a 12v motor only sees the 2v over for a short period of the cycle. If you want to work out for how long, you need to so some trigonometry with Sine waves.

There is no question that you are putting more energy into the motor and as a large percentage of the energy supplied is lost as heat, the motor will get hotter if run on 14v instead of 12v.

Digital power supplies are whole different ball game. In this case the extra 2v will be present all the time. If the consumer of the power supplied has a voltage regulator in the circuit designed for example to maintain a steady 10v output, then all of the extra volts will be "shed" as heat. If the current being supplied is 1 Amp, then the additional heat lost will 2 volts * 1 amp = 2 watts in addition to the (12 - 10) * 1 that was designed to be lost, so the heat loss has been doubled.

I don't know how DCC decoders govern the power to the motors. It seems unlikely to me that all the power would be routed directly through the on board controller, but I am sure that all DCC decoders have some voltage regulators on board to run their own circuits and supply power to the accessory outputs. If this is the case, you probably should not apply more DC track power than recommended by the decoder manufacturer. I also assume that it is this voltage regulator heat loss which governs whether the decoder manufacturer says it is safe to wrap them in tape or not. Lenz usually advise NOT.

David

 

[Gofer]

Sorry - entered in error

 

[Gofer]

I know of no resistive controller that supplies half wave rectified voltage to the track as the norm David. I know some traditional controllers do offer the option of switching to half wave rectification as pulsing DC (which is essentially what half wave rectification is) improves slow speed starting and slow speed control. As regards applying 14 volts to the motor causing it to run hotter, although this is true the 14 volts being talked about here is only present on the track when the controller is set at maximum - a postion rarely necessary and rarely used and providing Ryan avoids using the max setting on him controller he is unlikely to cause any damage to his Hornby motors.

Voltage control on a digital system does not produce heat. Voltage control on these systems uses technology where the supply to the motor is rapidly switched on and off and the average voltage the motor sees and reacts to is a product of the 'on' time verses the 'off' time. The heat produced in digital controllers in purely due to the current being taken by the motor. Although the voltage present on the track when employing these system may be high and present all the time, the motor will only 'see' what the on board digital controller allows it to see so all the power for the motor is routed via the on board decoder.

 

[dwb]

>half wave rectified voltage to the track as the norm
Sorry, bad description. What I wanted to describe is the sinusoidal nature of the wave form produced by a basic DC resistance controller which is not a nice flat line sitting, rather it looks like series of camel humps.

>does not produce heat.
As a categoric statement, I have to disagree because I believe in the second law of thermodynamics. There will be some energy loss and that loss will be in the form of heat. Granted there may not be a lot of heat, it depends on the design of the circuits. It is certainly the case that Lenz advise NOT to encase their decoders because it interferes with heat dissipation.

David