Question for Jward re: installing directional lighting on HO GP60

[jbrock27]

Jward, you obviously know your electrical stuff and I hope you can help me with this project.  I did search on previous topics on this and found Desertdweller's post of 11/3/12 but found I still had some questions.

    What I want to do is install directional lighting on an Athearn Blue Box GP60 using a piece of brass "c" channel that I solder to the top copper clip of the motor.  I want to use 2 led light bulbs and know I need to get 2 diodes, one for each light that will get attached to one leg of each light.
     One of my questions is: do I need to be concerned with whether I attach the diodes to the + leg of each bulb?  Another question: do you have a suggestion about what voltage leds I should get?  A third question: would I also need resistors?

I was hoping to tap into that vast knowledge of yours and that you are willing to share it.
Thanks for your help.   And of course, if anyone else wants to lend their advice, I would be happy for it.

[Desertdweller]

jbrock27,

You would not need diodes in addition to the LED's.  LED's  are Light Emitting Diodes. Since they are already diodes, they either give off light or not depending on the polarity applied to them.  My post was in reference in installing directional lighting in N scale units using incandescent bulbs.

What you should add in series with the LED's are 1K resistors.  LED's operate on a lower voltage than incandescent bulbs, and without resistors would burn out.

The thing to remember with any diode is that it will only allow the passage of current in one direction.  If the current flows, it will light up.  Otherwise, it will stay dark (certain types will change color instead).  As long as the power source is run through a resistor before getting to the diode, you should be able to test polarity by grounding one leg of the diode and touching the other to the resistor.  If it doesn't react like you want it to, switch the legs to the opposite power contacts.

DC locomotives are very simple: polarity determines which way the motor spins.  This same polarity determines which diode will light up.

You will have a lot more room in an HO locomotive than in an N scale one, so cramming everything in should not be a problem.

Good luck,

Les

[jbrock27]

Thank you very much for your reply Les.  I did not know that about LEDs as I have only previous experience with incandescents.  Does it matter which leg of the LED that I attach the resistor to?   And is there any visible way to tell which leg of the LED is which?  Do you have a suggestion of what voltage LED to get for what I have in mind.
Thanks again for your help with my project.

[jbrock27]

Yes, running the loco on DC.

Don't feel I quiet have all my answers yet guys.

Rich, sorry, but have no idea what you mean by "ma".  I see bulbs at Radio Shack listed in volts or watts.

[jbrock27]

Why is it so difficult to get help here on this discussion board?  This is really a simple, simple question, for all the experts out there.  I don't how much more detail I can give about what I am looking to do, which even I know, is simple-directional lighting.

Seems like if I want to know the name of song; I could get the answer;
Seems like if If I wanted to know if spray paint can be used to paint my cars; I could get the answer;
Seems like if I wanted to know how to set up a blinking red light, using a teddy bear, bailing wire and 1.5 volt battery; I could get the answer;
Seems like if I wanted to know what wires to use from my power pack and where to hook them up (uh AC or DC?); I could get the the answer;

C' mon guys.   A little help???

[jbrock27]

...and I did mean to say thank you Rich, for the sites.  Reading them now.

[richg]

Apparently i offended you so I removed all the references. I thought I was giving you the answer but I must have been wrong.

[jbrock27]

You didn't give me the answer, punitive jerk.
And didn't you see that I said thank you, before you decided to be a punitive jerk.  Thanks for sharing (or should I say coveting) your worldly knowledge. 

[Desertdweller]

jbrock27,

take it easy.  We are trying to help you.

I'm not an expert on this stuff, but I think "ma" is an abbreviation for milliamps.  Diodes have very low current draw, so the value would probably be expressed this way.

I suspect the voltage requirement for these LED's would be about 1.5 volts.

It doesn't matter which side of the circuit the resistor is applied to. 

The easiest way to determine which leg of the diode to apply where is simply to try it.
If it doesn't work the way you want it to, just reverse the connections.  Remember, the diodes will have to be wired opposite each other, so they will only come on when the loco is going the direction you want it to go.

That is as much as I can tell you.  I'm assuming you know how to solder.  You will have to solder to make your connections.  You can solder to the brass channel you want to use, but not to the cast frame,  I suggest you solder a light wire from a connection on the motor circuit of opposite polarity of the brass channel.

Good luck.

Les

[jbrock27]

Thank you very much Les, that is the add'l info I was looking for.

And I really do appreciate Rich's help as well, I really do.  He's been helpful on a few other subjects so far as well.  I don't know why he took my frustration as an insult and decided to act punitively by wiping away the sites he had given to me just previously.  But, he really did NOT provide me with the answers I was seeking-just basically told me to go off and look for answers, which defeats the purpose of my taking the time to come here and post the question.

I don't know why Jeff Ward never bothered to post a reply since he's been posting elsewhere since this afternoon.  I directed this to him, bc he always seems to know his stuff when it comes to electronics.  Of course, I am not saying others don't, no, not by any stretch. 

I  have to say, obviously, that I am frustrated with what I am sensing is a lack of spirit of cooperation and assistance from this discussion board.  Not in all cases, certainly not.  But, it seems to me that unless you are a member of the "club" or have 50+ years under your belt, no one wants to know ya.  This place appears to me to be more of place for people to top each other on what they know and what they can show the other guy, doesn't know.  That is not what I thought it was all about.  Sad. 

[jbrock27]

...and yes Les, I have the soldering part covered.  It was my questions about the bulbs/resistors/diodes that I needed the help with.   Thanks again for your time and patience. 

[jward]

jbrock,

others have given as good of an answer as i could on this subject. to paraphrase: the led's themselves are diodes, so you won't need additional diodes if that is all you are trying to do is directional lighting. you will definitely need a resistor for each led. it doesn't really matter whether you solder it to the cathode or anode as the two legs are called.

led's are rated in milliamps which are units of 1/1000th of an amp. they usually drop 1.5 to 2 volts at least the ones i've bought at radio shack. the package should have such data on it.. to calculate the resistor needed, use ohm's law in which voltage = current X resistance. so the voltage of the power supply minus the led voltage equals the voltage you use in the calculation. for a 2v 10ma led your calculation would be 10/.010 or 1000ohms.  that is a good starting point if you are unsure of the led's actual values.if it is too bright, up the resistance, too dim, lower the resistance.

hook up each led seperately. use test leads at first, run the locomotive and see which direction the led comes on. if the forward headlight comes on when going reverse, but goes out when moving forward, swap the leads. once it is working the way you want, disconnect one test lead at a time and make the permanent connection.

hope this helps.....


as an aside, what you are doing here is connecting the two led's in reverse polarity to each other. the same circuit can also be used, with red and green led's, for a polarity indicator for reverse loops. the led's could be mounted in those bachmann signals without too much trouble.....

[jbrock27]

Thanks Jeff.  Appreciate your offering your help before logging off.  I also appreciate Les' help and Rich's help as well.
Radio Shack is likely where I will go for both the LEDs and resistors.  On my multimeter, my MRC Tech II 1400 puts out around 16 DC max.  It certainly sounds like the 1K resisters on 3.3 V LEDs should work well.  The thing I hate to do if it can be avoided is to do things more than once, solder, resolder etc as opposed to being able to get it right the first time and set the bulbs up so they go an on when in the right direstion.  I am going to use the brass channel as the conductor and was going to solder 1 leg of each bulb with a resister to it.  The other 2 legs I was going to join to a common wire and solder that to the bottom copper clip on the Athearn motor. 

Maybe what I can do to start with is put a resister on the short leg of one bulb and on the long leg of the other and then touch them one at a time to the DC power supply, see which one lights when and then position them accordingly on the ends of the loco.  Make sense? Appreciate your info on the legs, etc.  I will try to use Ohms law-my father, the physics teacher would luv how much you site Ohms law
Thanks again for your help.

[jbrock27]

For anyone interested here is what I have found out/done so far.  I went and bought LED bulbs and resistors at Radio Shack this evening.

I found an on line piece about wiring LEDs for both DCC and DC purposes.  I am looking to use the LEDs for DC only so I went to the section on using LEDs in the DC scenario.  This is the site: http://www.brian-lambert.co.uk

The power supply (14v for me) minus the forward supply voltage value of the bulb (3.3v for the LEDs I got) divided by the forward current value of the LED (which is 25 milliamps)  The milliamp value gets the decimal moved 2 places before dividing so it becomes .025.  So 14-3.3=10.7  Then divide 10.7/.025=428.  428 is the minimum value need in Ohms for the resistor to safely run the LED at maximum brightness.  I ended up getting 680 Ohm resistors as opposed to 1000 Ohm resistors.  The resistors are 1/2 Watt, 5% tolerance.  We'll see what happens.

[jward]

there should also be a 560 ohm resistor as a standard part. or....two 1k ohm resistors in parallel equal 500 ohms.

to get the resistance value of parallel resistors, add the resistor values and divide by the number of resistors.


try different values and see which one looks best. max bright may not be what you want.