Cab Light Function

[Nodrog1826]

Planning a major re vamp of a 2040 Crok, going have it stripped down soon, its fitted with a Massoth sound chip.

Part of the work has me toying with idea of making the cab lights controllable, on in the relevant direction of travel, but with the option to switch off independent to loco lights. Have also seen somewhere a mod that apparently switches the light off as the loco moves off, and back on when it stops.

Any advice, CV tweek suggestions etc.

 

[PhilP]

If you want that level of sophistication, you will probably need to go to a different decoder to Massoth..
Zimo, or ESU both have more options as standard for lighting.

I could do it with Massoth, but would probably resort to a little external circuitry to achieve the 'off on motion' bit.

 

[Beddhist]

Why not just switch it manually with a function key? I did this with all head and tail lights on my blue Kamel, as I decided it's not correct to have lights on on the end facing the train. For shunting I can run it with both headlights on.

 

[shropshire lad]

I know that Zimo decoders ( both driving and function) have this ability as it's an effect I use on all my locos.
Engines with cab lights on when they are running just don't look right to me.

 

[PhilP]

Note to self:
Must get a Zimo to play with!!

 

[Nodrog1826]

It's just a thought at the moment, part of the servo operated, auto uncoupler, 8Fs, plagues of Egypt, upgrade I have mentioned in the past.

Kitchen work top take over project, for which I will remember to switch off the microwave first this time, don't want to repeat this....



That what happens when you switch off the microwave thinking you have switched off the controller, when stuffing the wires back in.

 

[shropshire lad]

You're in for some fun playing Phil, I keep finding stuff. It's worth keeping an eye on the updates too as they add extras to the decoders fairly often.
This is my track cleaner using standard LGB lamps and decoder effects for roof top strobes, fading in/out headlamps and auto on/off cab lighting.

 

[PhilP]

 

[andyspencer]

I've got cab lights set up on some of mine, the light in the cab of forward travel comes on as the loco stops, and goes out again as train pulls away. Loco fitted with ESU V4XL

 

[chris m01]

Andy Spencer sounds like the right idea. Although it is very common on model railways would a train driver have the cab light on while driving? You certainly wouldn't in a car.

 

[shropshire lad]

You can hardly see a thing with the cablight on at night when you are moving Chris. So maybe it would be on at low speed possibly when shunting but not otherwise.

 

[Ozymandius]

I have fitted my Croc with a Digitrax DG583S decoder (it was dc driven before I bought it) this separates control of the running lights from those in the cab. So the original circuit board is now in a jiffy bag - just in case...

As mentioned above, on the real railway you would not have a light on in the cab unless you were stationary and then for safety (so you don't kill yourself blundering about the cab) or "admin" purposes.

Best regards
Tony

 

[Deleted member 1986]

Been puzzling this for a while, LI-I the output for the cab light is slightly idiosyncratic in it's behaviour!



As well as being tied to LI-V & LI-H, has no associated or useful CV's, other than CV 50.



Whilst coming up with a transistor circuit to amplify the puny milliamp rating of a function output on a Massoth decoder, stumbled across an article that explained how a transistor could be used to act as a switch.



In layman’s terms, when LI-I is on and with a resistor in line at R1, the base of the NPN transistor would become saturated, and therefore the LI-I function to the cab light would be off.



When LI-I is off, ie when LI-V and LI-H are turned off via the light key on the Navigator, the transistor would then start to conduct, and LI-I then would turn on the cab light.



A rather convoluted methodology is required reach the correct value of R1, requires the following information, voltage out of LI-I (22v?), this is dependant on the setting in CV 50 (32?), the milliamp rating of the cab light, bulb (33ma?) or led (20ma?) fitted, HFE of the transistor (100ma?). Plus an addition of 30% to the figure, to ensure the base of the transistor is saturated and switches off. Once R1 is calculated, then just a simple calculation of 10* the value of R1 gives the correct value for R2.



R2 is included as a stabiliser to ensure R1 switches the base of the transistor correctly to either on or off.



R3, is a simple calculation of the value of DEK+ and the milliamp rating of the cab light, for a bulb somewhere around 330 Ohm, for a led a 1K resistor will be ample, if too bright increase the value of R3.



Doodling with a pencil and a calculator, trying out a variety of voltages and milliamp ratings R1 would be around 20K, and R2 would be 200K.



Bit tied up getting ready for our Indoor Meet this Sunday, will try the circuit out with the help of few of “The Old Gits” (The Gang) who will be present, they may well come up with a pearl of wisdom!