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Streetlight Distances


nhdesigns
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So I'm doing a rebuild of my scenery to consist of a main street going across my layout with some low relief buildings on one side and basically an open pavement on the other side, towards the trackside. One thing I do intend to have is some working streetlights, which I have and some spares to order. The only thing is I don't quite know the correct distance between each streetlight. I have added them before but because they are rather bright LED lights, even on 12V, they lit up everything around and something just didn't feel right about them. I do recall fitting them with a distance of 21mm between each light that I think might be why the illuminated everything as you can see by these pics.

 

Lights Out

Let there be light Part 2

 

I've done a web check to see it states that the distance between each streetlight is 200yds or 183m in real size but I don't know what that is in 1:76 scale. I used an online scale converter which has given a measurement of 2407.89 mm. Is that right? Or is it less? Can somebody tell me what distance streetlights should be in OO gauge please? 

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Based on 4mm equals 1 foot your calculations are correct. 200yds or 600 feet is 2400mm in OO scale.  However I feel here scale distance need compression. I placed my street lamps at junctions in the roads and at what looked to me to be like correct spacing along straight roads.

 

I found this with an internet search for current UK street lighting ...  

Mounting Height. To centre of light source, 25 ft.
Spacing. Generally not greater than 150 ft., but under occasional span may be as much as 180 ft. Where economically possible, spacing at 120 ft. may be adopted. For cut-off lighting, a figure substantially below 150 ft. is required.
Overhang. Maximum distance between the two rows should not exceed 30 ft. Maximum overhang of 6 ft. This is to allow the lighting of kerb, pavements and adjoining property. 

 

​Which makes the lamps much closer than your calculations 

Edited by Brian
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My understanding of street lighting design is that there is no 'standard' spacing in real life.  The position of lighting columns is determined by trying to obtain a minimum light intensity over a given area.  Therefore, the spacing depends on the height of the columns (the taller the lighting columns, the further apart they can be) and whether they are located on both sides of the road or just one.  If lighting columns are on just one side of the road, then they will be closer together than if they are mounted alternately on each side of the road.  Spacing will also vary depending on the type of light emitted.  Most road traffic accidents occur close to or at junctions and therefore these are generally better lit than sections of road without a junction.

 

I don't think there is a 'right' answer for your layout, just one that looks okay.  In my opinion, placing the lighting columns 2.4 m (8') apart would not look right - that's too far apart and wont produce enough light.  I'd be tempted to suggest that mounting lighting columns around 0.6 m (2') apart on alternate sides of the road would be about right, but you could reduce that a little depending on whether or not there are junctions on the road with the street lighting.  However, if you have the columns any closer than about 0.3 m (1') then I think that's too close.  I think it's just a case of trial and error.  Try removing or disconnecting half of the lights that you've already installed and see if you get the desired effect.

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So would 40mm or 50mm be a suitable distance? Or more?

 

When you say mm, I assume that you actually mean cm.  I think 40 - 50 cm (ie 400 - 500 mm) would be okay, but I think you'll just have to go for trial and error to achieve your desired level of light.

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I find with spacing of static things just counting the paces between a few real ones gives me the answer.  Hold you mobile phone close to your head, and as you go along count the number of paces, out loud. No one will notice because they will think you are nattering on your phone.

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My layout not being an accurate representation of anything or anywhere adopts the simple practice of how many lights do I have in the box and how much layout space to fill. Dividing one by tother equals the lampost pitch.

 

I’ll get my coat...

Rob

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The other factor in this is the brightness of your lights, looking at your photos they do seem very bright but this may be exaggerated by everything else being in total darkness.

LEDs normally need a minimum 3volt supply to trigger them after that they can get brighter with higher voltage and also burn out quicker. You mention a 12 volt supply this shouln't be fed to every LED either put resisters in series with each light to drop the voltage or couple them up so for instance you have four lights across a 12volt supply  so that each receives 3 volts.

Sometimes it is necessary to play about with the voltage to get the effect you want but it looks more effective when you have a pool of light under each lamp rather than a floodlit effect.

 

I have twelve LED  lamps in my MPD and I bought a switched output power supply 1.5-12 volts to supply them so that it was easier to adjust the voltage until I got the effect I wanted.

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I have twelve LED  lamps in my MPD and I bought a switched output power supply 1.5-12 volts to supply them so that it was easier to adjust the voltage until I got the effect I wanted.

 

You should *always* use a resistor with LEDs. You adjust the resistor to set the correct current through the LED. LEDs are not voltage driven.

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You should *always* use a resistor with LEDs. You adjust the resistor to set the correct current through the LED. LEDs are not voltage driven.

 

Or, you might even use a constant current source, then you can short out some of the leds to turn them off without blowing up the others in the string. Here's one example, but there are many other ways of doing it. The current is determined by R1/R2. If you want to vary the current you could substitute a potentiometer.

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Or, you might even use a constant current source, then you can short out some of the leds to turn them off without blowing up the others in the string. Here's one example, but there are many other ways of doing it. The current is determined by R1/R2. If you want to vary the current you could substitute a potentiometer.

Sorry I didn't make myself clear, all the LEDs I have bought usually come with something like a !k resistor supplied which I use or provide an alternative if not supplied. But the initial post on this thread seems to suggest that the LEDS are being driven directly from a twelve volt supply but makes no mention of how they are wired or if a resistor is used in the circuit. If so this is not correct and will probably result in damage to the LEDs.

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The vexed subject of LEDs comes up time after time. An LED is a diode. As such it has a 'forward' threshold voltage. (Normally between 1.8v and 3.3v depending mainly on colour) Below that it does not conduct at all, above it, it conducts completely, virtually no resistance. So unless the current is limited by another component , normally a simple resistor, it will quickly burn out. A 1k resistor is always a good starting point, increase if too bright, reduce if too faint. You can use one resistor for more than one LED, but if you're not confident with the calculations, keep it simple.

Edited by cliff park
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  • 3 weeks later...

The vexed subject of LEDs comes up time after time. An LED is a diode. As such it has a 'forward' threshold voltage. (Normally between 1.8v and 3.3v depending mainly on colour) Below that it does not conduct at all, above it, it conducts completely, virtually no resistance. So unless the current is limited by another component , normally a simple resistor, it will quickly burn out. A 1k resistor is always a good starting point, increase if too bright, reduce if too faint. You can use one resistor for more than one LED, but if you're not confident with the calculations, keep it simple.

so.....-   I know this is basics but that's me  -- so if I use 5 LEDs wired to my 16v [and presumably with an on/off switch somewhere] at the rear of my Gaugemaster, should one resistor at 1k usually be OKay?

Today I have experimented with 2 LEDs wired to my track and am pleased with myself in eventually getting some light into them - carefully guessing that I am not putting too much power in via the controller. I have found that they light only when the track is "going" in one direction - and show no life at all when "going" in the other direction. I feel I am making progress - slowly [very slowly] and will concentrate on scenery for a bit until I get more knowledge/experience/advice.

Any comments truly welcomed..

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LED's of the type we are talking about here consume very tiny amounts of power, a few thousandths of a watt. BUT they are diodes, the clue is in the name Light Emitting Diode, so they will only ever light up with the power the right way round. Reverse the power, no light.  If powering more than one LED through one resistor it does get more complicated. If you don't know how to do the calculations stick to one resistor per LED, they are only a penny or two each after all.

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Thank you Cliff,

 

I do get some satisfaction now from finding out for myself that they only work "one way", and that it wasn't just a fault somewhere in the contacts.

I shall now follow your advice and after we play Plymouth Argyle later today I shall get onto ebay and seek out some resistors; and then decide whether to power them from a 3v battery box or similar [an independent source would make it easier on my "removable" scenery parts which cover stretches of track] or from the Contoller [? the 16v connections in the middle at the rear of the Gaugemaster controller].

 

Much appreciated; thank you.

Trevor

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