Märklin DRG EG2 / #3747
- Doehler & Haass SD21A-4 sound decoder
- E 75 sound project
- LED lightning boards with red taillights

The red taillights are not yet perfect. I will shield the circuit board to prevent the red LED from shining through the board.

Video:

Pictures from conversion

Old C90 decoder removed:



Comparison of the size of the old C90 decoder and the new Doehler&Haass SD21A, which is smaller as the old one, including the MTC21 adapter board:



Thinking about this speaker which fit into the bulge:





Or to use the Märklin mSD/3 speaker:



There is enough space for a 1000µF buffer capacitor:



But then, You have to use the mSD/3 speaker:



The LED circuit board is hand made, equipped with a warm-white LED and a red LED, which shine down to the front lights, and there is another warm-white LED mounted on the other side of the board shining to the fiber optics to the upper front light:

Edited by user 27 November 2017 21:30:20(UTC)  | Reason: Not specified

Hi Alan,
yes, that could be a choice. I think, my Capacitors have a diameter of 10mm, I could by some with 8mm or 6.3mm diameter. Good idea, I will check the maximum lenght and by some. Then, I could fill the space completely with capacitors and set on top the speaker flat.

PS: Shit, I forgot to set the voltage in the capacitor konfigurator. 25V capacitors with 1.000µF have at minimum 10mm diameter! There is no 8mm capacitor with 25V voltage.

But I found 560µF and 680µF capacitors with 25V and 8mm diameter. They may fit into the space. It depends on the length, I haven't measured yet.

Regards,
Moritz