white leds and accu's

[Paul van grieken]

White leds has a forward voltage of 3V. The baterie in the normal faller cars is 2,4V. What did you do to turn the white leds on?
I have the yellow autobus from faller and there is no room for a second batterie?
All the best,
Paul from Delft Netherlands

[Jonas K.]

Hello Paul,

I used the Tams FCS-3 modul to run white Leds.
http://tams-online.de/htmls/produkte/fc ... _fcs3.html
This component doubles the voltage, so you can use white leds.

Another possibility is the MAX619, it increases the voltage of 2V up to 5V.

Jonas Keim

[H0-Holger]

Goede middag Paul,

here is a small layout for a step-up-circuit, the drawing is quite self-explanatory.

For a 2,4V power supply with a 3,5V LED you need to change the values of the resistors (1,1K instead of 10K, 3,2K instead of 27K) and the condensator (22nF instead of 100nF). These values are nearest to the ones I calculated using the formula given on this page - and indeed it works...

This is the page, where I found it. In general, it says that the values are not really important, even with quite incorrect values it should work (they used some parts they had at hand) - but I won't bet on it.

Brgds
Holger

[paul van grieken]

Thanks for the replíes.
I finally used the MAX619 with only 4 componemts that are small enough to fit in the faller bus. I installes 2 headlights and 2 backlights, looks great.
Paul van Grieken