Re: Multiple LEDs on FX-DO

Joó Ferenc

Thanks KJ and Peteski,

I will try to have the decoder read out loud the CVs although even at reset it didn't say reset.

For the diodes from the track pick-up, that should not be needed if I connect to the bridge rectifier, if I am correct.

Thanks for your input. Maybe I should get a new Programmer... Anybody has one for sale?

Best regards,

Ferenc Joó
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peteski7 via <> ezt írta (időpont: 2021. febr. 15., H, 4:23):

Hello Joó,
While I can't help with the decoder specific question, I have commend on the LEDs.

Instead of hooking up the LEDs in series, requiring rather high voltage., why not hook them up in parallel (with each LED having its own current limiting resistor)?  Yes, the wiring is slightly more complex, but not impossible.  Resistor (a small SMD 0603 or 0805 size) could be installed directly at the LED's lead, so you woudl just need 2 wires for the string of LEDs.
While the typical operating current for larger size white LEDs is often specified 20mA, most smaller SMD LEDs (0402, 0603, 0805 size) have operating current of 5mA.  Either way, even 5mA is often too bright for applications other than headlights. Often 2mA (or even less current) produces realistic brightness.  With that in mind, you could easily run a string of parallel-connected LEDs using standard function output, and the decoder's common positive power (either 5 or 12V).

As far as creating an external source of positive voltage (the blue wire), you can build a very simple circuit that will do that.

Instead of using 2 discrete diodes, there are pairs of common-cathode diodes in a 3-pin packages available to simplify the construction.

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