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Smoke Generators and decoder choice:

The most commonly available generators are made by Seuthe. Apart from the multiple shapes, sizes and heat insulation variants, there two electrical choices for OO/HO models - 70mA and 120mA. The trade off here is low current, high operating volts and vice versa. The 70mA does not work very well with most DCC systems sold for OO/HO which means the 120mA is the one to choose. This in turn means that at least one of the function outputs on your decoder needs to be capable of sourcing 120mA. Not all decoders sold for OO/HO fitting have this capability. Those that don't tend to be the smaller decoders intended for fitting in very small spaces.

Controller choice
Since you have stated a preference for controlling smoke, you should choose a controller that makes function operation easy - one press on, one press of. A few controllers require multiple presses to get things done. That eliminates a couple but there's still a huge choice left.

David
 

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120 mA capable decoders:-

There's only one way to be sure a decoder has the function current capability you want and that is to read the specification sheets / manuals very carefully. In other words we can advise and suggest possibilities but it's your decision


A quick glance at the Zimo manual for their HO range of decoders - link shows the total function output capability is 0.5A (500mA). It is not obvious if there is a limit for each function, I suspect that information is buried in the documentation. I would be pretty certain that trying to pass 500mA through one function output would not be possible.

I would expect that checking the specs for the ESU LokPilot (ie non sound) decoders would show that they also have outputs capable of driving 120mA. I see no reason to change this part of the decoder design.

As a rough guide, the larger the physical size of the decoder, the higher the function drive capability is likely to be simply because more current requires larger components to handle it. Having said that I am amazed that the incredibly small TCS DP2X-UK manages up to 1A for the motor. The two functions are 100mA each however.

Point switching
Switching points via DCC is expensive but you don't have to do it all in one go. I am starting with a panel and arranging the switching so that more than one controller or panel can make the change. By having switch position feedback, each controller gets an update when someone else changes it.

To interface a computer to a DCC system, all you need is a computer interface for your main command station. Most control systems either have this as an option or it comes as standard from the outset. There is no direct connection from the point decoder back to the computer. Getting the point position information back to the command system is a different matter. Although RailCOM has been touted as the standard for feedback on an NMRA compliant DCC system, its been a long time coming and I don't think there are too many point decoders which support it. There are several feedback buses - the Lenz RS bus, the S88 bus used by Maerklin / ESU and I'm sure Digitrax must have something as well.

Control Panels
There have been several topics on the Forum on building control panels with LEDs. I did one a long time ago - link. Expat has published a few topics on his panel; they are well worth seeking out. Expat has also published a lot of diagrams on how he uses DCC Concept's Master Switches.

I think I've given you more places to look than answers. I hope this helps.

David
 

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QUOTE that control panel is fantastic, I'm sold!
Thanks for that.

QUOTE is the same kind of panel possible (where the LED's indicate point position) or do you need additional components?

I put this panel together before DCC Concept's MasterSwitches had had a wide exposure on the Forum. I think they will provide all of what you need in one package and I think there's a track occupancy option as well. I'm sure a Master Switch user will be along shortly to clarify this.

For myself, I feel competent to source the components I need. For point feedback I have an extra micro switch which detects the current point setting and this information goes straight back to the panel LED. For track occupancy my plan is to use current detectors such as this item from LDT. As a MERG member, I will probably get their current detecting kit instead. The important point to note about both of these detectors is that they rely on an AC signal to work. In other words they are DCC only; they won't work on DC.

To pursue either path - MasterSwitch or DIY - you will need to do some soldering. It's not the micro surgery that can be required for some hard wired DCC installations but it's something you need to be comfortable with.

As with all big projects, break it down into manageable pieces and tackle them one at a time.

David
 
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