Analogue, DCC, and some basic Newbie questions . . .

Railway42 said:
There is no need for a switch. Most DCC decoders will work on DCC and DC but not on analogue PWM which will harm the DCC decoder. You will also find that DCC will run on a much dirtier track than DC.
Click to expand...

PWM and the DCC signal are both pulses of full voltage applied to the track, but with different mark/space characteristics. PWM doesn't harm the decoder, just confuses it as the firmware cannot reliably determine whether it's seeing DC or a DCC signal. This can lead to erratic running and sudden changes of direction which can strain and strip gearing etc. Some decoders can cope with PWM better than others, but I agree that the advice to avoid PWM track power with decoders is very sensible.

Decoders can be fitted with (or may even include) a "power buffer" which keeps the circuitry alive and can supply power to the motor for brief periods of interruption of the track power (dirty track, insulated point frogs etc.), but it's no substitute for keeping the track just as clean as you should with DC. The good thing about DCC is that the constant full voltage in the track does help cope with voltage drops at track joints etc. Power buffers can cause problems when running a decoder-fitted loco on DC (loco continues to run after DC power turned down or off), and often need to be switched out of circuit in that situation.
 
PWM is a pulse 0 volts to maximum voltage i.e. 0-24 volts. DCC is Bi-directional pulse i.e 24 volts negative pulse 0 volts 24 volts positive pulse so are not anything like the same. LGB and Massoth both warn you about PWM and there warranty. ??? ???
 
Railway42 said:
PWM is a pulse 0 volts to maximum voltage i.e. 0-24 volts. DCC is Bi-directional pulse i.e 24 volts negative pulse 0 volts 24 volts positive pulse so are not anything like the same.
Click to expand...
Yes that's right, so if anything the PWM maximum voltage is effectively only half that of the peak-to-peak DCC signal. What I'm saying is 1) a decoder is designed to accept a form of pulsed power as input, and 2) if the decoder is rated for (say) 24v linear DC it can handle 24v PWM and there's no way the pulsed nature of the PWM signal itself can physically "harm" a decoder.

PWM can interfere with sound systems not designed to handle a PWM input.
 
I guess I should re-phrase my statement. When I said Analogue I meant DC with the big old knob (potentiometer) that makes it go faster.

So basically what I have come to understand by all the wonderful input is a DCC Engine will run on a DC track, it just might take longer to come to a stop when the "dial" is turned to the off position?
 
Handsomerob said:
So basically what I have come to understand by all the wonderful input is a DCC Engine will run on a DC track, it just might take longer to come to a stop when the "dial" is turned to the off position?
Click to expand...
That sort of overrun is possible if a large capacity power buffer is fitted (they're usually an optional extra). Users of such large power buffers in their locos sometimes program the decoder NOT to allow operation on DC if they don't expect to be running their locos on DC.

Typically when you run a DCC fitted loco on DC, you turn the dial up a little before anything happens as the loco needs around 7 volts in the track before the decoder circuitry "wakes up", and then off she goes. When you turn the power off the loco stops straight away. If you turn the volts down to a stop too slowly then the loco may stutter slightly as you cross the cusp of voltage required for the decoder circuitry, but it depends on the decoder. You soon learn how to get a smooth looking starts and stops!
 
If you have a decoder equipped loco, which also has a power buffer, then you must turn 'off' DC operation in the decoder..
Else it sits there, with the buffer charged, and when you turn the power off, the buffer discharges through the system and the loco can travel several feet! - Amusing the first time it happens. As long as there is enough clear track!
 
Hi there! I'm a complete Noob too, so it might be the case of the blind leading the blind here...

Have you considered Piko? http://www.piko-america.com/

I'm just starting out and because my wife is from Canada, I wanted to model a railway with a Canadian flavour. Piko do a DC starter set and a number of wagons (with more coming out this year) for the White Pass & Yukon Route http://wpyr.com/ which is one of the few remaining Canadian narrow gauge railways.

It appealed to me because I don't have beaucoup de bucks right now, and all of Piko's DC engines are easily upgradeable to their own DCC system so I can go to DCC if I suddenly become rich in the future (ha ha).
 
Hi Paul, glad to see you've started posting, welcome to the Monkey House! ;)

How are you enjoying the starter set? :)

Jon.
 
[quote author=PaulC link=topic=300741.msg346907#msg346907 date=1426923222]
Hi there! I`m a complete Noob too, so it might be the case of the blind leading the blind here...

Have you considered Piko? http://www.piko-america.com/

I`m just starting out and because my wife is from Canada, I wanted to model a railway with a Canadian flavour. Piko do a DC starter set and a number of wagons (with more coming out this year) for the White Pass & Yukon Route http://wpyr.com/ which is one of the few remaining Canadian narrow gauge railways.

It appealed to me because I don`t have beaucoup de bucks right now, and all of Piko`s DC engines are easily upgradeable to their own DCC system so I can go to DCC if I suddenly become rich in the future (ha ha).
[/quote]

I did go with Piko,

BO_1.jpg

Pretty neat DCC setup.
 
HandsomeRob: Excellent choice! I believe Piko have some Canadian National liveried engines and rolling stock coming later this year. The only thing I'm a little dis-chuffed about is that Piko don't seem to do any North American diesels, but other than that I reckon they can't be beat for reasonably priced North American steam engines and rolling stock.

ZeroGee: I've got my White Pass & Yukon Route starter set puffing round the lounge right now, but I'll start another thread about that to avoid derailing HandsomeRob's topic.
 
You must log in or register to reply here.
Back
Top