# Mini bulbs, diodes and stuff



## Totalwrecker (Feb 26, 2009)

Feasible?

Parts: Mini bulbs ... T-1, 5v, .15 amps, .75 wats
........Diodes 1N914 from RS
....... Battery; 14.8v 4400mAh Li-ion
....... Loco; Aristo new C-16, gutted. No smoke, If I had to give it up, then.....









What I want to do is run 2 Series of 3 bulbs. 1st series; Headlight and Classlights. 2nd Series; Reverse light, cab light and firebox.

Functions desired: Forward; Series 1, Backwards; Series 2, Stopped Series 2. I'd prefer constant voltage lighting, but realise for directional it's easier to use motor leads.
3rd part: I'm willing to use a manual switch to activate while parked, but how do I prevent back flow to the motor? Don't want to unpark it as I daydream...









For the Experts: Is there a device that monitors motor polarity and can switch a seperate circuit for constant voltage lighting direct from battery?

Era 1920s, slow mine runs so lights will be dim as the motor won't get full power if I use motor leads.

If the Gizmo is expensive I'll just go manual with a DPDT if I can't add the 3rd option with what's on hand.

For me we must use the KISS method and I would prefer pictures rather than symbols, the chemo scrambled some of those cognitive skills. I get caught going back and forth in my mind until I get frustrated.... and the project gets put off.

Thanks in advance,

John


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## Dick413 (Jan 7, 2008)

John 
i'm have brain fart but why can't you use those little black things with silver band? hook one on forward side for headlight and one on the 
backside for rear light 
dick


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## Greg Elmassian (Jan 3, 2008)

The 1n914 is a "signal" diode, high speed switching is it's forte, not rectification of power. 

The current rating is 200-300 ma, and .500 watts. 

I think you can see from those specs it is unsuitable (hint, an inductive load will exceed the steady state current when switched on or off) 

So get a 1n4001 "rectifier" diode. 1 amp and 50 volts if I remember right. 

Hooking one series across the motor will do your "forward". 

stopped needs something more... 

I'd use a relay, and get one to activate at low voltage, so with a diode it could trigger in forwards, and another with a diode in the other direction trigger in reverse. Get a single pole double throw and in the unenergized position, send battery power to the stopped lights. 

One manual switch to disable power drain in "parked" mode... 

Should be pretty easy... at work, can draw a diagram later, but maybe Todd, the king of relay logic (meant as a compliment by the way) would have the time to draw it up for you. 

Regards, Greg


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## Totalwrecker (Feb 26, 2009)

Thanks Greg, 
That was helpful, I figured you'd know faster than my typing in the values... on those diodes. 

My budget is tight, I'll go with what is on hand. 

I'll probably go to a DPDT and tap the battery. My reverse lights aren't so much for reverse as the front coupler is a decoration. I installed a headlamp under the cab roof so it lights up the tender load. While sitting on a siding, waiting for the Brass Hat to roll by, the fireman can restack the wood and reduce his steps on the next leg. Stopped one can look in and see the hogger checking his orders and the firebox glow. 

Thanks, 

John


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## Greg Elmassian (Jan 3, 2008)

Please take pix of your tender load at night if you get a chance, that will look cool. 

Yes, the basic thing is trigger the relay with the motor and then have the relay switch full voltage to your lights. More parts but more voltage to the lights. One spdt relay will do forward and park, or reverse and park. 

I guess you could do forward and park with the relay, and the reverse lights just with a diode across the motor... I think that is what you are saying. 

Regards, Greg


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## Totalwrecker (Feb 26, 2009)

Sure thing on that pic, but I've got the Rubicon to cross first! 

Far simpler than your parts drawer my friend, a toggle under the tender most likely, forward: headlights, back: tender crew. 
Just like a crewman had to go to the headlight to dim it, I'll have to bend a knee and flip it. 

John


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## Dick413 (Jan 7, 2008)

Greg do you still need to use this 1n4001 "rectifier" diode with the relay or can you use the other one? 
thanks dick


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## Greg Elmassian (Jan 3, 2008)

It's really the wrong diode to use, look at the specs on the current again, 2 tenths of an amp... just the wrong type of diode. Diodes are really cheap. 

Greg


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## Dick413 (Jan 7, 2008)

ok thank you 
dick


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## Totalwrecker (Feb 26, 2009)

Dick, 
Those diodes were the result of ignorant shopping, I was actually focused on another item and the clerk was bothering me, so I asked for some diodes... 
I finished gathering my stuff and threw the bag into the mix. 
I got 50 of 'em, anybody want them? 

John


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## Dan Pierce (Jan 2, 2008)

Greg, 1n4001 is 50 volts at 1 amp, but I prefer the 1N4002 at 100 volts. Much safer especially for people using 28 volts where 100 volts is batter protection. 

PS when using a signal diode they will at some time or another short from reverse voltage. I have seen this many times in my job.


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