Power Supply for R8247

[Bodgedlitter]

Hi all,

Does anyone know if the Hornby accessory decoder, R8247, can have its input voltage supplied from a separate power supply rather than using the DCC track supply?

If so, is it 15VAC?

Many thanks

[P-Henny]

No it can't.....and it isn't proper 15 VAC either.

The R8247 is operated by DCC data signals that are carried by the DCC track power. So if you don't connect the R8247 power input to the DCC controller output, you have no way of telling it what to do.

The DCC track voltage is not proper AC, it is a bi-polar square wave where the pulse width defines whether the signal is a digital binary 0 or a digital binary 1. The peak to peak voltage is typically 28.8 volts at a nominal frequency of 7.1Khz, but this reads typically about 15 volts on an AC range multi-meter. Basic cheap multi-meters are calibrated to read true sinusoidal AC at 50Hz (0.05Khz), so the high frequency DCC bi-polar voltage readings on a standard AC meter are only indicative of a voltage being present.

I am assuming that you are asking the question because you are experiencing weak power, insufficient to robustly operate your point motors. If this assumption is correct, then you are victim of one of the R8247 product weaknesses. It is gutless and has a weak internal CDU. I had to overcome this problem by using my R8247's to operate external relay contacts that then operated my points via an external more powerful CDU with a 19 volt DC power supply input.

[96RAF]

The input not only supplies power but also the DCC signal with the instructions on which point to fire, so short answer - no you cannot power it separately. Why would you want to.

[Bodgedlitter]

Thanks, I have sorted my 'issue' - I wasn't leaving enough time for the between activations for it to charge up.