LED'S what are they and how are they used?

Rhinochugger said:
That's strange because all the directional LEDs that I have on my battery locos rely on having the wrong current when running in the wrong direction - i.e. the rear LED will have reverse current (and therefore will not illuminate) when the loco is going forwards and vice versa.
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If you wire the front and rear LEDs in inverse parallel it'll work fine with the lit led acting as the blocking diode for the unlit one.
It's not really a "blocking diode" as it conducts rather than blocks but it prevents any excessive reverse voltage across the unlit diode.
 
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Neil Robinson said:
If you wire the front and rear LEDs in inverse parallel it'll work fine with the lit led acting as the blocking diode for the unlit one.
It's not really a "blocking diode" as it conducts rather than blocks but it prevents any excessive reverse voltage across the unlit diode.
Click to expand...

Having looked up wiring in inverse parallel on Google, I am not the wiser. Would you explain this, please?
 
I have a Gaugemaster analogue controller which I could use.

Ntpntpntp, initially I didn't know what I could achieve with them. They were very inexpensive so it doesn't matter if I ruin them anyway.

Could they be used as a string of lights along a platform or for lighting sidings? What about lighting a signal box?

They add another feature to my layout.

SW
 
Having looked up wiring in inverse parallel on Google, I am not the wiser. Would you explain this, please?


To use a 'plumbing analogy:
A diode is like a 'flap-valve', it only allows flow in one direction..
So if you put two of these in parallel, but one 'the other way round', you can feed water (electrical current) 'in' from either end, and one or other of the devices will allow 'flow' through it.

If we now imagine by 'elek-trickery' we can make the flap-valve glow, when water runs through it.. Depending onwhich way the water is flowing, one or other of the devices would glow.

Does that help? Or just leave you in a sea of confusion? :)
 
Sarah Winfield said:
I have a Gaugemaster analogue controller which I could use.

Ntpntpntp, initially I didn't know what I could achieve with them. They were very inexpensive so it doesn't matter if I ruin them anyway.

Could they be used as a string of lights along a platform or for lighting sidings? What about lighting a signal box?

They add another feature to my layout.

SW
Click to expand...

Anywhere you have power, you can have light Sarah.. :):nod:
 
Sarah Winfield said:
I know nothing about LED's so having bought some off ebay it would be useful to know how they are used. Would a member help please?

The description is:-

"L12303W Pre-wired 3mm Bright White LED lamp light set 12v~18v
Forward Current 20mA/30mA"

They comprise a 9" lenght of wire with a tiny see through bulb and a resister.

Thanks.

Sarah Winfield
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I must ask - If you know nothing about LEDs, what they're used for etc, why did you buy them!
 
PhilP said:
Having looked up wiring in inverse parallel on Google, I am not the wiser. Would you explain this, please?


To use a 'plumbing analogy:
A diode is like a 'flap-valve', it only allows flow in one direction..
So if you put two of these in parallel, but one 'the other way round', you can feed water (electrical current) 'in' from either end, and one or other of the devices will allow 'flow' through it.

If we now imagine by 'elek-trickery' we can make the flap-valve glow, when water runs through it.. Depending onwhich way the water is flowing, one or other of the devices would glow.

Does that help? Or just leave you in a sea of confusion? :)
Click to expand...

To add to the confusion, "Yes".
 
JimmyB said:
I must ask - If you know nothing about LEDs, what they're used for etc, why did you buy them!
Click to expand...

I'm sure that here Sarah is well aware what she can use them for, just unsure how to go about using them - e.g. power sources, types of power, connecting up.
 
Neil Robinson said:
If you wire the front and rear LEDs in inverse parallel it'll work fine with the lit led acting as the blocking diode for the unlit one.
It's not really a "blocking diode" as it conducts rather than blocks but it prevents any excessive reverse voltage across the unlit diode.
Click to expand...
Ah, understood, thanks Neil
 
JimmyB said:
I must ask - If you know nothing about LEDs, what they're used for etc, why did you buy them!
Click to expand...
I can see you living to regret that query Jimmy. Had my mind racing all sorts of answers that I will not nay dare not say on here!
 
Neil Robinson said:
Is this diagram any help?

View attachment 243238
Click to expand...
Well, I guess the small arrows represent light and the black triangles the two LEDs. Guessing further, the resistor is wired to the positive side one LED and the negatives side of the other and at the other end, as it were, the negative of one LED and the positive of the other are wire back to earth(?). But then again, maybe not.
 
The triangle with the "Bar" is the universal electrical symbol for a Diode... Light Emitting Diode.

The 2 "free" wires go to power, does not matter which is plus or minus... or plus and earth..

electrical current flows like water, has to come from somewhere and go to somewhere, otherwise known as a complete circuit

Here's one with power drawn in...

819d02d2aec9c9e3c51c6236f84b4f1a.gif
 
Neil Robinson said:
Is this diagram any help?

View attachment 243238
Click to expand...
Understand that now, but not why if positive comes from the resistor end the left hand Led does not get trashed. But will take your word for it and try it sometime on my Maplin Testing gear. Presumably the juice takes the line of least resistance IE the Right hand Led making light on the way?
 
dunnyrail said:
Understand that now, but not why if positive comes from the resistor end the left hand Led does not get trashed. But will take your word for it and try it sometime on my Maplin Testing gear. Presumably the juice takes the line of least resistance IE the Right hand Led making light on the way?
Click to expand...

By George! I think he's got it! :):nod::nod:
 
If I take a 9V PP3 battery and connect the wires from my LED (one with a resistor and the other without) to the + and - connectors will the LED light up please?

Similarly if I take a second LED and wire it the same will I then have 2 LED lights, etc. etc.

If I then replace the battery with the DC output of my analogue controller will it work the same please?

I do appreciate I tend to ask quite convoluted questions.

Thanks,

SW

PS. If I then connect the LED's to the rear socket of my Stainz locomotives (bearing in mind I am DCC) and ran LED's attached to wires to each of 3 or 4 carriages will I have then lighted each carraige?
 
Sarah Winfield said:
If I take a 9V PP3 battery and connect the wires from my LED (one with a resistor and the other without) to the + and - connectors will the LED light up please?
Click to expand...

Yes. - Polarity is important!

Sarah Winfield said:
Similarly if I take a second LED and wire it the same will I then have 2 LED lights, etc. etc.
Click to expand...

Yes.

Sarah Winfield said:
If I then replace the battery with the DC output of my analogue controller will it work the same please?
Click to expand...

Yes. But you need to get the polarity correct.

Sarah Winfield said:
PS. If I then connect the LED's to the rear socket of my Stainz locomotives (bearing in mind I am DCC) and ran LED's attached to wires to each of 3 or 4 carriages will I have then lighted each carraige?
Click to expand...

Yes.*

*Though, as others have stated, you really ought to put a blocking diode in the circuit. - Try this with ONE of your LED's as they may not like this too much.
 
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