Wiring 5v lamps

[Mr Grumpy]

I'm installing a Zimo MX699KS decoder into a large scale locomotive, which has 5v lamps which I intend to keep (for the time being) The loco runs at 19v and I wondered which is the most effective way to drop the voltage for the lamps? I have a selection of 1000 and 2000 ohm resistors, but wondered if there is a better way of voltage reduction. There are head/tail lights and a separate cab and 'brakeman's hut (on the tender) light. As well as the full voltage outputs, the decoder has one 5v and one 10v output. 

Any help appreciated!

[Nigelcliffe]

I assume you're reading the Zimo manual for the decoder.    On Page 5 of the English language version is a clear diagram.   For any function, you can feed it from 5v, 10v, a user-set variable voltage, or "track voltage" (which appears to be 19v) in your case.   

So, for the 5v lights, they should be connected so one wire to the light connects to the 5v supply, and the other wire from the light goes to the function output to allow it to be switched on/off from the throttle.   Nothing else, no resistors, or other faff. 

 

- Nigel

[Mr Grumpy]

Hi Nigel,

thanks for the tip. However, as the decoder only has one 5V terminal, how would I use the F0 function for front and rear lights. And there are also the separate  cab and brake house lights to consider.

Richard.

[Nigelcliffe]

As per the diagram.  And same as if you used the "blue" wire, except you'd blow the bulbs on 19v. 

 

The 5v wire has to be taken to one side of every bulb.    The other side of each bulb comes back to its function connection for control.   

 

Whether you can use an existing commercial wiring in a loco depends on what the maker has provided.  But if all the lights are 5v, then it will be just connecting one wire to the "common" parts of the 5v bulb wiring.

 

 

 

[Mr Grumpy]

Thanks guys!

 I have taken a look at the Zimo diagram, this time with my reading glasses! I’m sure I can now give it a go.