Katzhagen - Archive - March 2009
An illumination for the VT98's interior
was required as the vehicle should not remain dark at night. I decided to build a homemade illumination based upon warmwhite LEDs and a current control circuit instead of going for a commercial product.
Testing a suitable circuit
The extremely low voltage drop of the 1N5818 diodes allows for a constant
illumination already at a voltage of just 3.5V on the track.
The electrolytic capacitor irons out tottering contacts and hence provides
a flicker-free illumination. The LM334 IC takes care of the current control.
Almost finished board and LEDs - comparing dimensions
Complete board before mounting it
View into the "power compartment"
The wooden bars turn the board into a plug-in module
Cutting a stripe of ABS polymer for mounting the LEDs
The board's size was adapted to the dimensions of the VT98's toilet compartment.
The same procedure was used for the driving trailer. The little wooden bars
turn the boards into plug-in modules which results in easy maintanance.
The board which exists ex factory on the VT was used to provide the new board with the track's voltage. The driving trailer's collector shoes were equipped with cables which were led into the car's interior after applying suitable drills to supply voltage to the board inside the driving trailer.
A stripe of ABS polymer was used to make the lights under the vehicle's roof. Drills were applied to fix the stripe at the vehicle's housing and for mounting the LEDs.
The board which exists ex factory on the VT was used to provide the new board with the track's voltage. The driving trailer's collector shoes were equipped with cables which were led into the car's interior after applying suitable drills to supply voltage to the board inside the driving trailer.
A stripe of ABS polymer was used to make the lights under the vehicle's roof. Drills were applied to fix the stripe at the vehicle's housing and for mounting the LEDs.
5 LEDs and drills for mounting the unit
The picture illustrates the light's length
A small hole for the LED, a wide one for fixing the whole thing
The light's ends vanish under the roof
Connectors provide for easy maintanance
Collecting current via the driving trailer's trucks
Simple wiring inside the VS98's chassis
A view of the roof in the passenger's area...
and in the driver's area
Five LEDs provide for a more than just sufficient illumination.
Three warmwhite 1300mcd LEDs illuminate the passenger area and two white 900mcd LEDs provide light in the driver areas. The great difference regarding the color suggested by the picture does not match the real impression. Actually, the light is quite pleasant since the supplied voltage is only 90% of the nominal voltage (just 2.97 instead of 3.3V). Hence the current consumption is significantly lower than specified. In fact the total power consumption of this circuit and the five LEDs is just 60mA.
