Power for LEDs (buildings/street)

[Lindsay-373053]

Hi all,

I am a complete newbie to railway modelling. I have decided to go with easier track plan for my first layout and use the oval track in pack and ext 1-4

so will have 2 ovals.

I will be using the HM2000 to power the tracks as separate ovals.

As such I will have the controller supplied in pack spare.

I would like to put some (4/5) leds in buildings and have 20 total street lights.

Q1: Could these be run off the Hornby controller that comes with the pack? Everything in RM seems to be 12V but the R7729 is 14V and I feel that 2V will create an issue. If not what is best

Q2: what do the points run off as again the controller is 14V but I’m now seeing that they should be on a 16V AC? (They aren’t essential yet but seeing YTers putting points on a 16VAC instead of 12V/ or the 14V Hcont. has confused me so I don’t really want to wire them yet)

Additional thought: I will have insulated frogs between the 2 points to the inner circle. I saw that in a YT video from a well known modeller too but now I’m wondering why you can’t connect them together if you have two trains running separately . It made sense at the time!

As I’m new I don’t want to over complicate or blow myself up!

Any help for either of the Qs or additional thought would be appreciated.

Thanks in advance folks,

Lindsay.

(00 Gauge track etc)

[P-Henny]

If you use the controlled output of the spare R7229 to run the lighting, then the voltage is variable and can be set to 12 volts or less. Noting that the output of the R7229 is PWM and not pure DC, but you don't need to concern yourself with what PWM is at this time (Google PWM if you want to know). The main advantage of using the controlled output of the R7229 for lighting is that you can use the speed knob to control LED brightness. Note that you must leave the direction switch alone and leave set to either forward or reverse (I suggest forward as an arbitury suggestion). The reason for this is because LED lighting is polarity sensitive and will go out if the voltage supplied to them is reversed.

Solenoid point motors need a lot of current to operate robustly. The 14 volt DC output of the R7229 does not have a lot of current capability. But this does not stop you using the fixed AUX 14 volt output to operate your points. You just need to connect the 14 volt output of the R7229 into the input of a CDU (Capacitor Discharge Unit). The CDU contains capacitors that are charged up from the R7229 14 volt output and it is then the capacitors that provide the required high current kick to robustly operate the points. Note that the R7229 has an internal CDU for this function, but that does not stop you adding another external CDU if you find the internal one not powerful enough. You could as an alternative just dedicate the R7229 to powering your lighting and connect a CDU to the AUX output of the HM2000 controller and this would be my preference as I know from personal experience that the HM2000 works very well with an external CDU. Search ebay for CDU and you will find loads to choose from, the ones listed in ebay as "RKcdu" are particularly good value.

cdu for sale | eBay

A CDU is also a 'fail safe' device. The way a CDU circuit works prevents the possibility of burning out the Solenoid motor coils if there is a short circuit in the switch wiring or the wrong switch type is installed (one that is not 'momentary action - see further below').

With regard your confusion over point operating voltages. The solenoids will operate over a range of voltages so no one is particularly right or wrong. The optimum DC voltage to operate a Solenoid is deemed to be 19 volts DC, but 14 volts DC will usually be OK too. At 12 volts DC, Solenoid point operation robustness starts to fall away (this is why the AUX output of the R7229 is 14 volts DC and not 12 volts DC). 16 Volts AC has been the traditional historical way of operating Solenoid points, but using AC instead of DC makes the Solenoids 'buzz' which some may find annoying. If you 'full wave' rectify and capacitor smooth a 16 volt AC voltage you get an equivalent DC voltage just above 20 volts, hence why 19 volts DC is typically used, because 19 volt DC power supplies are easier to source. Each model railway builder will have their own preference for powering Solenoid point motors, hence why you have seen conflicting advice in your research.

Note that CDUs can be powered by either DC OR AC and can accept all the voltages stated above.

Note that operating Solenoid points require the electrical switch you use to be a 'momentary action' switch, sometimes also referred to as a 'passing contact' switch. The internal design of Hornby's R044 point 'passing contact' operating switch makes the Hornby switch not 100% compatible with a CDU, but PECOs PL26 point operating switch is ideal with CDUs as are any of the industry standard electrical toggle action 'momentary action' SPDT (Single Pole Double Throw) switches.

With regard your question relating to Insulated Rail Joiners (IRJ) between the loop to loop crossover points. Fitting these is optional, fitting them or not fitting them each have their own advantages and disadvantages. I favour fitting them. There is a good description of their use in the pinned sticky thread at the top of the 'General Discussion' forum titled "Getting Started (Sets and Track-Mat Expansion Packs)". Some very old steam locomotive designs that split the power pick ups between the loco and the tender will stall when crossing points with IRJs fitted, but most locos (and more modern ones) can accomodate IRJs being fitted or not.

MY REPLY IS VERY LONG PLEASE DO NOT REPLY TO IT USING THE 'QUOTED REPLY' OPTION IN THE 3 DOT MENU.

[SteveM6]

As Paul said, to achieve reliable point motor operation you will need to include a CDU. Easy to fit and ou will never regret it.

Turning to your lights, I would recommend buying a DC/DC converter, sometimes referred to as a buck jumper. You feed it with a supply from either the aux output or a separate transformer. An adjuster on the unit allows you to set the output voltage to a level suitable for your lights. Remember LEDs should also be fitted with a suitable resistor. The real advantage is that the supply cannot be accidentlt turned up and potentially blow the LEDs. Some converters have a display to show input and output values and are available on Amazon or eBay and are quite inexpensive.

For two loops always fit two isolating fishplates on the crossover - best practice that will prevent shorts. Don't skimp for the sake of a few pence.

[bill7437]

I found that an economical way of powering LED building and street lamps

if you just want them either on or off was to buy via ebay a mains to 3 volt

DC plug in transformer/rectifier which can either be connected via a single pole switch or just left to plug in when lighting required.These items are reasonably inexpensive.I have powered over 20 LEDs via this method.

[Topcat2018]

@LI

There are lots of discussions about powering LEDs on the forum. Just go to General Discussion and type LEDs in the search box followed by the ENTER key.

[Flashbang]

Lets get some electrical facts right then move on.

AC (Alternating Current) in the UK is at 50Hz. (60Hz in some other countries). There are two main values associated with AC - The RMS value which is what is read on a meter and usually referenced to as the supply voltage and then there is the Peak voltage which is 1.4 times larger than the RMS. Peak isn't usually referenced but it needs to be kept in mind when dealing with AC. As an example..... If you pass 16 volt AC RMS into a Full Wave Rectifier (Bridge rectifier) you will get out a reasonable DC which will be minus 1.4 volts the RMS read voltage of the AC. So, if you read exactly 16v AC then expect to obtain 14.6 volts DC - each rectifier in the bridge reduces the voltage by 0.7volt. There are always two rectifier diodes in circuit in a bridge rectifier. While this output is DC is not that smooth and really isn't suitable for powering electronics. Here and for a smoother DC a capacitor is installed across the DC output. This will lift the DC volts to the AC Peak value which is 1.4 times that of the RMS value minus the diodes in the bridge. So in our 16v AC RMS example adding a capacitor (Usually an electrolytic type) it increases the DC voltage to..... 16 times 1.4 minus the volt drop in the diodes or 16 x 1.4 = 22.4 - 1.4 = 21.0 volts DC. This is what a CDU uses in Solenoid point operation and it would charge to if the input were exactly 16v AC. Please bear in mind that 16v AC isn't always the case even if the items rating plate says it is! It can be more or less than the rating.

As for LEDs, while the standard LED can work on AC ideally with inverse diodes or a series diode, they are IMO best operated from a separate regulated and smooth DC power source. "Regulated" means the output volts remain at the rated voltage regardless of load, up to the maximum current rating of the power supply. Example... A 12v 1.0 amp power supply can power well over 100 lit LEDs with suitable series resistors fitted. These wall socket plug-in power supplies are readily available and are quite cheap to buy. eBay, Amazon etc have plenty and are at times sold under the heading of CCTV power supplies or LED power supplies. What voltage to use? Many will opt for 12v DC but you could use 5 volts DC or whatever you decide upon. Whatever output volts you decide on, always fit a series current limiting resistor to your LEDs. Failure to fit a resistor will where the supply volts are above the LED rated voltage destroy the LED in a split second! Using the same voltage as the LED rating is playing somewhat with luck, as not all LEDs have the same forward voltage rating and without a series resistor you will run the LED at its maximum current, with a series resistor you reduce that current to a level far more acceptable - often 5 milliamps (0.005Amp) per lit LED or at time even less. I would argue against using a Train controller as its all too easy to reverse the supply polarity and these devices usually provide way above the supposed 12 volts, frequently they can reach well above 20 volts with little load such as a few LEDs. However, here the series resistor will help protect the LED(s). What value resistor? It all depends on the supply volts and the rated If (current forward) and Vf (Voltage forward) of the LED. A rough rule of thumb is on 12v DC I use as a minimum a 1K (1000 Ohm) 1/4 watt series resistor and more so a 2K2 (2,200 ohm). By increasing the resistance you reduce the LEDs brightness and current drawn to around 5 to 10 millamp. You can often go to 10K (10,000 Ohm) or more before the LED fails to illuminate. It doesn't matter which lead of the LED the resistor is fitted into, but do try and keep to the same throughout for simplicity.

LEDs with wire leads will have the longer lead as the Anode (Positive).

[Topcat2018]

@Flashbang

Very interesting, but without explaining the terms you use your dissertation will probably mean little to people who are absolute beginners when it comes to electrical/electronic circuits.

Alternating current?

Hz?

RMS?

Full wave/bridge rectifier?

Capacitor?

Resistor?

Forward voltage?

Anode?

Ohms?

They say a picture is worth a thousand words and some actual diagrams of circuits to use with LEDs would be helpful, as would the simple equations used to calculate resistor values.

[Brew Man]

Or go to his website in the 'Useful Links' sticky at the top of the general forum. Plenty of diagrams and equations there.

[ntpntpntp]

Going a bit heavy on the technical bamboozling for a newbie :) Keep it simple.

Power the LEDS from the controller accessory output (lets assume around 15V AC) . Using a 12V DC voltage regulator / rectifier in the circuit would be better but not essential. Make sure each LED has a current limiting resistor of at least 1000 ohms (1k). If you buy LED lights for model railways they often come with such a resistor fitted to one wire or included for you to add. If desired you can add more resistance to lower the current and reduce the brightness. Wire each LED/resistor combination in parallel across the power supply so each sees the full voltage.

Power typical solenoid point motors (eg. Hornby, Peco) also from the controller's accessory output, but strongly recommend using a Capacitor Discharge Unit (CDU) to give a brief but powerful "thump" of power and then protect the point motor from burn-out. Use momentary push buttons or switches for points.

Get into the habit of fitting isolating rail joiners between pairs of points which face each other (for example at a crossover between two ovals). You'll want to use a separate controller output for each oval. To run across from one oval to the other you simply set both controllers to the same speed and direction.

[P-Henny]

If you navigate to BrewMan's suggested "Useful Links" thread, then note that 'Flashbang' is listed as 'Brian Lambert'. Thus it is the link to "Brian Lambert's Home Page" that you need to follow to see the diagrams.

[Barry-350851]

On my own LED light projects, I'm running various LEDs from a couple of 1amp variable voltage regulated power supplies. The yard lamps were sold as 3v, the street lamps were 12v and a 12v LED strip that came on a reel and were stuck to the ceiling of the diesel depot. The yard lamps have 1k ohm resistors on them, the street lamps already had resistors on.

Even at that, the light intensity was quite bright so I turned the variable voltage on the power supply down to 9v and am happy with the result. My hope was that running a lower global voltage would prolong the life of the lights.

[Mikey1707822023]

It is personal choice but I always use a separate 12v supply for lighting and sound modules. I tend to go for 4A power adapter. For points, I use a 16V power supply and I never, ever have any issues. I buy 12v lights that have resisters already fitted and connect them via distribution boards, so no soldering is required.

[morairamike]

I use small DC to DC PSUs. They are cheap and easy to wire up. I split my street lights into sections, my houses and shops into zones. By using these PSUs you can set the brightness of the lights to different levels for more realism.

[Bulleidboy]

I have used a variety of PSU's with voltages varying between 3v and 12v. Resistors fitted in each case, and the on/off switch in each case is a dimmer switch (voltage regulator). I have had not trouble (blown LED's) since I installed everything. The shop lighting is left "bright" on the ground floor and then varies (home made diffusers) to dim lights on other floors. All lighting was installed during build.