LED & Smoke Unit DCC Question for Flying Grande 4-6-0

[Todzilla]

Hello all, I just received my D&RGW™ Flying Grande 4-6-0 and I am planning on putting a Blunami (BLU-4408) DCC decoder in.

My question is when using the the supplied jumper wire board, to wire in the Blunami, is there a need to wire in an inline resistor for the Front & Rear LEDs & the Firebox Flicker LED? Or since we are using the plug in jumper board, the 4-6-0 motherboard already takes care of voltage, basically doing the part of the resistor?

Also does the smoke unit on the D&RGW™ Flying Grande 4-6-0 draw more than 300 mA? If so, then I can NOT use one of the FX outputs on the Blunami as it would exceed the 300 mA limit. If that was the case, do you recommend wiring the smoke unit into the track pickups? Or the the motor outputs?

Click here to see the 4-6-0 to Blunami Wiring

I appreciate any advice, or opinions you may have.



Thank you,

-Todzilla

[Greg Elmassian]

The motherboard takes care of the LEDs, logic level current.

I think the smoke unit might also be in the same way... but direct wiring will be more tha 300 ma... I'd ohm it out....

if it is the same as the dash 9 (meaning it has the socket) then perhaps it works the same:
J1-8 Smoke Activation 11.2mA  The smoke unit itself draws up to around  0.6A. but this current is funneled through the + and - connections and not through the function pin.



Greg

[StanAmes]

All the function pins on the socket used by bachmann (including the smoke pin) are low current control function pins and have all the protection circuits inside the locomotive.

Using the smoke unit as an example, the smoke function pin is low current while the power to actualy produce smoke is consumed through the + and - pins.

In your wiring diagram you have neglected to connect the + and - connections to the locomotive.  Without these connections there is no power being provided to the locomotive to operate the functions. The total current of all the functions and the smoke unit draw goes through this connnection so do ensure that your product can support the load.

Please also note that your locomotive had an excellent chuff unit.  I do not believe that the product you are using can take adadvantage of this feature.

Hope that Helps

Stan

[Greg Elmassian]

Thanks Stan. Is it safe to say all current production with the socket have logic levels for lights and smoke?

Is there an easy way to tell this? (I suspect the first locos with the socket, which I think was the shay, did not have this).

Greg

[StanAmes]

Greg  the first loco with the socket was the K27.  None of the Shays ever had the socket.

It is my understanding that the function pins for all Bachmann locomotives that have ever had the socket are low current pins.  Thats part of the design.

The + and - connections are not low current.  These pins power the elecronics, the functions, the smoke unit, and the fans.

Stan

[Greg Elmassian]

Ahh, the Shay was "dcc ready", but no socket.

On the K27, the earliest "socket", I do see that the smoke heater is indeed switched with a transistor, which should be in the current range of most function "outputs". The transistor is an 8550, which is a high gain PNP.

But, you have to supply voltage to a PNP to conduct, so the logic may have to be reversed from a normal function output, just like the chuff needed to be.

So, you are indeed correct, thanks Stan.

[Todzilla]

Thanks everyone for the responses! I'm glad Bachmann decided to go this way with the logic board socket. It makes it easier to not have to worry about adding individual resistors for LEDs and other accessories.

In your wiring diagram you have neglected to connect the + and - connections to the locomotive.  Without these connections there is no power being provided to the locomotive to operate the functions. The total current of all the functions and the smoke unit draw goes through this connnection so do ensure that your product can support the load.

You are absolutely right Stan! I realized after I uploaded my picture and looked at it later I was missing those connections. I have since fixed it:
Click here to see the UPDATED 4-6-0 to Blunami Wiring (feel free to give it a once over to see if I missed anything)

Also George over at Soundtraxx says the BLU-4408 is a 4amp maximum decoder so I'm crossing my fingers this should be fine.

Please also note that your locomotive had an excellent chuff unit.  I do not believe that the product you are using can take adadvantage of this feature.

Yes George also did state that the BLU-4408 does not have a chuff trigger. The decoder has an internal digital cam in that it can watch the motor power using BEMF and know a rotation of the motor. You can adjust the chuff in the decoder to match the motor rotation. Although I agree, it would be nice to use the optical sensor in the Loco.

I appreciate everyone's feedback.  I will hopefully post pictures of the upgrade (assuming it is successful )


-Todzilla

[Todzilla]

All the function pins on the socket used by bachmann (including the smoke pin) are low current control function pins and have all the protection circuits inside the locomotive.

Using the smoke unit as an example, the smoke function pin is low current while the power to actualy produce smoke is consumed through the + and - pins.

Hey guys, after re-reading through the responses, I got a crazy, longshot idea. Looking at what Stan (and others) have said about the "low current function pins", I was wondering of I could bypass the decoder and wire the "chuff sensor" pin/wire directly to the "smoke unit" pin/wire?

The thought would be every time the optical chuff sensor detects a revolution, it would "trigger" the low current smoke unit. So essentially the smoke unit would be timed with the "chuff".

This of course excludes the chuff SOUND, but the decoder can be programmed to match the motors feedback and I can offset it to match the chuff sensor. Worse case is I can wire the smoke unit to one of the FX connections and just turn it on and off, but really like the ide of a "synchronized chuff".

Obviously I can just do an experiment and temporarily tie the two connections together, but I don't want to make a costly electronics mistake by frying something.

Let me know what you think.




Thanks,

-Todzilla

[Greg Elmassian]

I did not think the smoke unit is fan driven? Modulating the heater will not make it puff... it's a resistor that has thermal mass... it will not switch on and off rapidly like an LED.

I pulse a fan motor, leaving the heater pretty constant, lowering and raising the heater current with speed somewhat.

[Todzilla]

I did not think the smoke unit is fan driven? Modulating the heater will not make it puff... it's a resistor that has thermal mass... it will not switch on and off rapidly like an LED.

I pulse a fan motor, leaving the heater pretty constant, lowering and raising the heater current with speed somewhat.

Thanks for the clarification Greg. Actually upon further investigation, there is no fan unit in the Bachmann to "pulse" the smoke unit anyway. It's just either "on or off".

Click here for Bachmann 4-6-0 Smoke Unit

In this case I will just wire it to an FX terminal. Then I can remotely turn on the smoke unit through the app.



Thanks,

-Todd

[nymark]

After my Phoenix MS18 quit working, I wanted to put a Zimo MX697 in my Bachmann C-19. I couldn't find one and settled for a Soundtraxx 4400. Does this decoder wire similarly to Todzilla's 4408? It's in and runs the engine but the headlight does not come on the firebox flicker only works in reverse. Thanks to Toddzilla for the wiring schematic seen above!