|Updating the Zimo equipped Class 60 with headlights automated to only switch on when the loco is on the move and adding a "Yard lighting mode" (both front markers on without the headlights).|
A thread in the RMweb forum, initiated by Norm81, revealed that the headlights of Class 60 locomotives are only enabled when the locomotive Master switch is changed from neutral to Forward. The marker lights stay on while that switch is in the neutral position. This is why photographs of stationary Class 60 locos often show the headlight in the off state, while the opposite side marker light is clearly on. This provided an interesting lighting challenge.... complicated by the classic Hornby negative ground lighting PCBs (unless of course your 60 was sound equipped from new, in which case its all a lot easier as the lighting PCBs on new sound 60s have decoder friendly positive ground.)
So the first task is to reconsider the overall lighting requirement. Next, to come up with a hardware solution and finally to find the best way to get the Zimo decoder to provide output(s) that only switch on when the loco is on the move. (Easy within the normal function mapping arrangements on a LokSound V4, but at first sight, I didn't have an obvious solution on the Zimo decoder!..... sorted now!)
DB Schenker liveried Class 60 as received. The intended recipient of the modified lighting system.
|The Lighting Requirement:
My Class 60 has a tension lock coupling at the rear (end 1) but has non operational cosmetic couplings, hoses etc at the driver's end (end 2). So a train will only ever be coupled at end 1 and the loco can only double head if in the lead position. Therefore I only need the ability to disable the running lights at end 1. (Mainly when hauling a train). So the requirements can be summarised as follows:
Light engine: Directional running lights at both ends with day or night switching but appropriate headlights only active when the loco is not stationary.
When in train hauling mode: As above but with all running lights at end 1 disabled.
Cab light (at driver end 2 only): Independently switchable but disabled if the locomotive is not stationary.
Note: Forward running lights when on the move consist of either day headlight on right hand side plus day marker light on left hand side. OR night headlight on left hand side plus night marker light on right hand side. When the locomotive is stationary, the headlight is not illuminated.
Yard Operation mode: Both front markers on together but no headlights! (light engine and in train operation.) (Headlights are kept off to avoid dazzling yard staff.)
Yard Super-shunter mode: All 4 markers and all 4 rear lights on simultaneously (no headlights). (Headlights are kept off to avoid dazzling yard staff.)
|The Hardware solution:
1) Independent access to the headlights:
In the original PCB, the headlight and marker light combination consists of two white LEDs, each with its own small series resistor (33 ohms) connected at the anode. The LED and series resistor pairs are connected in parallel, with both LED cathodes hooked up to the common negative track and the two series resistor ends hooked up to a positive control pad. See diagram below:
Original Lighting PCB circuit (Much larger external series resistors are used to define the total LED current.)
Photo of an earlier version of the same PCB with spring contacts (now replaced by plain solder pads)
The headlight LED anodes can be isolated by removing R2 and R5. Anode interconnect wires then need to be soldered to the R2 & R5 pads nearest to the edge of the PCB.
For my third go at a solution: This is a simple update to the original circuit in my Zimo 60 and it appears to give enough flexibility to handle the information on operational lighting received so far.
Using P-channel MOSFETs in place of the PNP bipolars, could save a few resistors.
FO7 uses Zimo's "only on when stationary" feature, to disable all headlights when stationary.
Swiss mapping is used to group the required combinations of lights for the required lighting modes.
At each end, a couple of extra resistors and two new diodes are added, while SMD resistors R2 and R5 are removed and their outer solder pads are wired back to the new parts on the back of the cab bulkhead.
Rear bulkhead of number two end cab, ready to be wired in again.
It would be a much neater job with SMD components!
This section is revised to take advantage of a Zimo firmware upgrade to version 34.10, which has 13 Swiss mapping groups, which enables a better lighting control arrangement to be used.
Summarising the lighting requirement:
NB: requires F8 to be available.....if its not, use any other available key up to and including F 12 and amend the FO5 key assignment quoted below.
CV131=60 to automatically switch off the cab light (FO5) when the loco moves.
CV159=60 to make FO7 off when stationary and on when moving.
Remove fader key from F19: Set CV313 to zero.
Add volume down to key F27: Set CV396=27
Add volume up to key F28: Set CV397=28
Note: If all operations are required to automatically shut down the headlights when stationary, simply leave key 19 pressed
Revised Function Mapping:
Subsequent to the video, another super shunter lighting mode became apparent, this is now incorporated into the design and included in the above information.
Super Shunter Mode (now also incorporated).
|Supplier website links: