allocation of function keys to aux outputs

[mikeg]

I have just installed a Zimo sound decoder in my Heljan Class 31, I have the headlight working in the forward direction and all the sounds, I have put the tail & cab lights together with the fan on aux 1 to 5, how do I change the high F11 to F 15 to work the lights?

 

Also does it matter which lead the resistor goes in for the leads, I ask as I put the resistors in the red wires and only the head code forward is working, I tried changing the reverse end to the black wire and it still does not work, have I blown the LED's?

 

Hope somebody can help

 

regards

 

mike g

 

p s  I first posted this in special interest DCC sound by mistake!

 

 

[chaz]

It doesn't matter at all which side of the LED you connect the resistor. The current will be limited whether it's on the anode or the cathode. Check the polarity of the connections - if they are the wrong way round the LED will not work but it is extremely unlikely that you will have damaged the LED(s) by connecting it up reverse-biased. Missing the resistor out will do that!

 

Chaz

[tender]

Have a look at the Zimo manual page 24-31 which describes the function mapping. It should be possible to do what you require by changing a few CV's but I think the upper function limit might be F12 for mapping to the outputs.

[Nigelcliffe]

The "Swiss Mapping" part of the Zimo manual should allow functions to F28.  For conventional functions, just set the "F" key, ignore the modifier key.

 

This is somewhat easier with a computer and JMRI, but its possible from a DCC handset.   This assumes the decoder has at least V32 firmware, if it is a reasonably recent purchase, I would expect the firmware to be at V32 or newer.    If the decoder is not V32, then it can be updated. 

[tender]

The "Swiss Mapping" part of the Zimo manual should allow functions to F28.  For conventional functions, just set the "F" key, ignore the modifier key.

 

This is somewhat easier with a computer and JMRI, but its possible from a DCC handset.   This assumes the decoder has at least V32 firmware, if it is a reasonably recent purchase, I would expect the firmware to be at V32 or newer.    If the decoder is not V32, then it can be updated.

 

Thanks Nigel, having seen the 'Swiss' in the title I've never read that part of the manual as I thought it wouldn't be relevant to British outline. Can't think of ever wanting to use functions to F28 for my Locos but you never know. At least I now know how to do it if the need ever the arrives.

[Phil S]

Referring to the Secondary Part of the OP Question: LED wiring and resistor positioning...

 

When choosing 'which lead' to put the [series] resistor in, it does not matter electrically which lead it is in, IF it is AFTER the 'common positive (blue) has split to each individual destination. - i.e. it is in series with the (LED) and both are between the common positive and the switched function (low active in most cases - but there are more options on recent Lenz/Zimo decoders??? not discussed here).

 

IF PLACED IN THE BLUE (common positive) lead, you MAY be using the same resistor for multiple lights - and the brightness of these can be affected by the combination of lights which are switched on at the same time.

 

For example: A 3-legged LED providing Red or White directional lighting:  

In the Central (common positve-Anode lead), only 1 resistor is needed for the Red/White lights - and the normal plan is for only 1 of them to be on at a time !   However, if both (perhaps on separate function buttons) were left on together, then double the current might be expected through the resistor, and therefore double the voltage drop ... and, depending on values, this may dim or extinguish one of the LEDS .... in the red/white case, and the worst possible scenario, it could turn off the white LED thus causing confusion !!

 

ALSO, if wired in this way, there is no hardware-opportunity to adjust the relative brightness of each.

 

HOWEVER, if 2 resistors were used: 1 in each Cathode-lead  (ie 1 in Red, 1 in White), with the Central common left directly connected to the Common positive, EACH value can be chosen to set the preferred brightness, and this will not be affected if both were switched on accidentally together (although the light output would obviously be a combination of white and red)

 

A similar situation CAN arise if you have a mixture of 'White' LEDS of different types, or White in parallel with Red  - as in early, simple alternate directional lighting - because the voltage across different types of LED can vary (from about 2V with RED through to 3+V with White and UV LEDS) ...

 

If sharing the same resistor, with the different LEDS in parallel, the LED voltage will be limited to the lower voltage type's value ...  ie if Red and White LED are wired in parallel, the white would probably NOT light.  For CONTINENTAL locos; with 3 white headlights, the top central light might use a separate LED of a different size and type to the lower pair, for example.  For 'parallel' White and Red LEDs (eg simple front white and red rear lighting on 1 output) EACH LED needs its own resistor.

 

ANOTHER CONSIDERATION: Particularly if using 'flashing LEDs' which actually contain an integrated circuit controller, and the LED(s), is that MANY of these are DESTROYED by a REVERSE VOLTAGE of ONLY 0.5V.  Many LEDs will be damaged or destroyed by 5V in reverse .... particularly if only a low value of resistance is in series.

 

IF there is a risk of 'misconnection' at any time  - whether during servicing of a loco [body to chassis etc], or attaching it electrically to more of the train (for example to provide controlled coach lighting) is is ALSO a GOOD IDEA to protect against 'shorts' or reversed connections: For Example: Using Roco 4-pole Power Couplings between coaches or loco and coaches etc for controlled lighting further down the train: It is possible to short the wrong connections during plugging. In this case, a low-value series resistance near the source (decoder) in the common positve lead, and/or a diode will help minimise the risk in this case....  I have taken to buying pre-wired JST connectors on Ebay in 2,3, or 4 way, to make internal wiring more serviceable and 'modular'

[mikeg]

Thanks for the answers given, I have sorted out some of the problems with changing the polarity of the LED's, Heljans pcb does this on the outputs from the resistors I discovered, the other points have been answered under the DCC sounds under special interests by pauliebanger, see also my extra questions about being able to read the chip.

 

regards and thanks

 

mike g