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Post by grabbem88 on Dec 22, 2014 4:58:27 GMT -8
I have done this before but wondered if installing 4 resistors on the neg pads really necessary??
What if I just add one 1k resistor in my +14 spot then run all my pos to that and run the neg as they need to be??
Just curious because I think we are wasting resistors and space..
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Post by grabbem88 on Dec 22, 2014 7:08:26 GMT -8
Well I tried it and it worked fine and not as bright as one would think
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Post by mlehman on Dec 22, 2014 7:32:25 GMT -8
It's way too early for me to think too hard on this one...
The resistor is for protection first of all. It should work OK as far as it goes. But if you develop a short in one of the circuits, depending on where and what it is and what shorts it, it may not be sufficient to protect the circuit. Something to do with where the resistor is placed in the circuit, before or after the load, too, but I'm blanking on the explanation.
If you want overall dimmer lights, this sort of works. But if you want different brightness lights, then the individual circuits make it easy to run more or less resistance to achieve that. I usually add more than 1k as a matter of course. A 1k resistance usually leaves things ways too bright for me.
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Post by grabbem88 on Dec 22, 2014 7:58:01 GMT -8
I think that's why ulrich models did it the way they did
Everything is really balanced which shocked me because normally the ditch lights would be brighter..
The only thing I did which most you guys wouldn't do is re use the athearn wire..
Magnet wire for me never sticks well for and I always snag and break them..
The athearn wire helped me in that situation.
The ditch housings was my only reason in not doing athearn genesis models that and breaking stuff but 50% alcohol and good pliers made it simple..
Maybe I should put a pic up?? I know alot of people get intimidated by this since we all hate when a factory athearn bulb goes out
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Post by lyled1117 on Dec 22, 2014 8:06:57 GMT -8
The resistors limit the current passing through the LED. A specific resistance can only pass a fixed amount of current for a specified voltage. If you attach one LED to a resistor, that LED will get all of that current. If you attach a second LED, the current through each LED will be half of the available current. Add a third, the current in each LED is only a 3rd of the available current. Because modern LEDs are pretty efficient, you may not be able to see much light intensity difference between full and half current, but keep reducing the current through a single LED, it will get dimmer and dimmer. If you are lighting four LEDs with a resistor, they will be dimmer than a single one using the same resistor. If you want to use a single resistor for all four LEDs, use a value that is 1/4 of the 1K value, that is something close to 250. 240 ohms and 270 ohms are standard values that would do fine. You could probably go close to 470 ohms {half of 1K) and not see much change in the intensity of the LEDs. HOWEVER .... because of the additional current, the wattage rating of the resistor should be at least 1/2 watt. You're possibly replacing four smaller resistors with a bigger one that will be hotter.
ETA:
This is all based on the presumption that all these lights are lit by a single function. If in fact you are lighting different LEDs with different functions, then at minimum use a resistor for each FUNCTION adjusted for the current desired.
Lyle
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Post by grabbem88 on Dec 22, 2014 8:55:07 GMT -8
Lol I goofed somewhere and been out of the tsunami loop
Fwd lights go off in rear and in rev both come on until stopped then fwd lights go off
I remember I had to do something to my atlas 8-32bw that uses a gn board but can't remember
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Post by mlehman on Dec 22, 2014 9:36:43 GMT -8
OK, now I remember why you sometimes want individual resistors on the negative leads. That way if it ever gets shorted, anywhere along the positive lead, the LED will likely still be protected. If you put one resistor on the 5+ pad and feed all four, then all four circuits are unprotected between the location of the resistor and the LED if the wiring is compromised. Only matters if something goes wrong, but given my luck...
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Post by grabbem88 on Dec 22, 2014 9:46:39 GMT -8
Whoops!! My rear lights wire was touching one of those fuse blocks or whatever cause right now after moving it away the lights work as they should
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Post by Mark R. on Dec 22, 2014 9:49:34 GMT -8
Still, not a good practice. If you turn on one function - that resistor needs to be a high enough value for just that single LED. Turn on another function, that resistor now has to limit the current for two LEDs and so on for all four functions.
It would be different if you were running four LEDs off a single function using a single resistor. But you are using a single resistor on a variable one to four LED load at any given time.
LEDs are just pennies apiece. Don't try skimping on something so basic. Unless you are installing LEDs in an N-scale hand car, you have plenty of room for them.
Mark.
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Post by grabbem88 on Dec 22, 2014 9:55:14 GMT -8
Yeah I took off shell on my 8-32bw and see why I followed the norm. Figured I'd try it but my oversight got the better of me lol
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Post by grabbem88 on Dec 22, 2014 9:57:21 GMT -8
What if I added to the ground pad with the addition of the pos ??
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Post by Mark R. on Dec 22, 2014 13:13:29 GMT -8
What if I added to the ground pad with the addition of the pos ?? Not sure what you mean by that .... The +14 volt pad should be common to each LED. Each function pad should have its own resistor to the LED. Mark. |
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Post by grabbem88 on Dec 22, 2014 14:07:04 GMT -8
No matter that weight that slides under decoder where the truck wires run through shorted the decoder and killed it..
The motor smells burnt as well. And upon further inspection the motor tab was also touching that weight as well.
Hopefully soundtraxx can discount me one
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Post by mlehman on Dec 22, 2014 22:51:57 GMT -8
Soundtraxx can usually repair a toasted Tsunami. IIRC, the charge is $40. Service and turnaround times have always been prompt. Call their customer service department.
If it's a new decoder, I believe that they will replace it free within 30 days of purchase (check you paperwork for details). That can be a good reason to buy only when you're ready to install.
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Post by grabbem88 on Dec 23, 2014 15:56:00 GMT -8
They took care of it. Gotta live soundtraxx!
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Post by grabbem88 on Dec 24, 2014 16:55:50 GMT -8
 For the record this is a factory dcc/sound install from athearn |
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