I am buying some 6 volt street lamps for the layout. They come with my choice of a 12 volt (82 ohm) resistor or a 16 volt (150 ohm) resistor. The transformer that I will be using has a 12v variable DC, a 16v AC, and a 12v DC. Regardless of the choice of outlet, I do want to under power them and give them a softer, a dimmer look. - OR - should I just disregard the resistors and just hook the 6 volt street lamps in a series of 3 or 4 lamp posts per unit, and do it that way? And/Or use the variable DC to control the dimness.
I'll start out assuming you are talking incandescent bulbs here. Much different answer if they are LED's.
If you want to use the power pack you referred to, I'd go with using the variable DC and inching it upwards until you get the brightness you are looking for. Be aware, however, if by mistake or otherwise the voltage goes very far over 6v the lamps are going to blow.
I prefer to use wall warts to power accessories. I have a (sort of) local surplus electronics dealer from whom I buy many electrical/electronic things. Among them are several variable voltage wall warts. I would set one of them to 4.5v or 5v, plug it in to my daisy chain of power strips and forget it. When the layout power is on, the lights go on. When the layout power is turned off, no lights.
Good luck!
For a while, I pulled wall-warts out of my parts box, which seems bottomless at times. It all works, but after a while I ended up with a tangled mess and an outlet strip full of wall-warts with extenders so I could use all the outlets.
I have since standardized on 12 volt bus lines for all my accessory lighting. I bought a couple of hefty 12-volt, 4 amp supplies from All Electronics. If you look at most wall-warts, they're generally in the 1/2 to 1 amp range. So, as you add more lights, you rapidly fill up one and you need another, hence the outlet strips full of small units. The last time I looked, they are now selling 5-amp supplies instead of 4, for about the same price. Progress.
Most of my bulbs are 16 volt. So, I'm under-driving them, which gives a softer, more golden glow, and it greatly extends bulb life. I model the Transition Era, so that's the kind of lighting which is more prototypical. Modern-era lights would be brighter and LEDs would not be inappropriate. I would try putting 3 of those 6-volt bulbs in series and driving them at 12 volts to see how they look. If they're too dim, put 2 in series.
Finally, a word of caution: Wall-warts and even the nicer supplies I use do not have circuit breakers. To make them safe as household devices, they have internal fuses. Since these are sealed units, the fuses are not replaceable, so once you short or overdrive one of these, it's suitable only for recycling. So, it is good practice to install a fuse of your own in series with the line coming out of the supply. You can buy fuses and fuse holders at Radio $hack for a few dollars. Get fuses that are rated at less than the supply, so you've got some margin before that one-time internal fuse gets antsy.
It takes an iron man to play with a toy iron horse.
SilvertonRRI am buying some 6 volt street lamps for the layout. They come with my choice of a 12 volt (82 ohm) resistor or a 16 volt (150 ohm) resistor. The transformer that I will be using has a 12v variable DC, a 16v AC, and a 12v DC. Regardless of the choice of outlet, I do want to under power them and give them a softer, a dimmer look. - OR - should I just disregard the resistors and just hook the 6 volt street lamps in a series of 3 or 4 lamp posts per unit, and do it that way? And/Or use the variable DC to control the dimness.
I had this problem years ago with 9 volt bulbs. I never understood why the street lamps came in 9V when power was 12V. Anyway I connected two of them in series, then put the sets in parallel. It worked fine and was simple. The only disadvantage would have been if one burned out it would take its twin with it. Never happened but it could have.
In your case since they come with the resistor, it might be best to check the specs from the vendor to see if the resistor is already "matched" to run them at bit lower voltage and dimmer. Otherwise I might recommend to get the resistor for 16volts and run them on the 12 volt power supply. I mean we could speculate anything here only guessing what the real life brightness is going to be and what it looks like in your particular situation. You might have to trial and error the resistors vs. various series/parallel arrangements to get them to achieve the desired effect.
Given the supply you asked about, I would wire them in series sets of four and drive them with the 16VAC supply termini. That way, all of the output will be powering lamps. Putting a resistor in series simply wastes power to create heat.
The 12VDC termini have a full-wave rectifier, which simply wastes some AC voltage from the winding. Lamps are not polarized, but LEDs are, and Tortoise switch machines need DC.
Why four in series? That gives each lamp 2/3 rated voltage, which should yield that soft, yellowish light typical of ordinary street lights. It also extends lamp life. Then, if you switch the lamps on at `dusk' and off at `dawn' they will last longer still.
(I personally use 12.6VAC filament transformers, and put three 6V lamps in parallel.)
Chuck (Modeling Central Japan in September, 1964)
Using the variable output is perfectly safe, IF you do the following:
Measure the voltage at the full throttle position.
AND
Design the lighting to work on this voltage without exceeding the bulb rating.
This way, you can safely run at the full throttle position without the lights buring out, but you can also turn them down for a nicer glow and increased life. AN accidental turn of the knob won;t blow up anything this way.
--Randy
Modeling the Reading Railroad in the 1950's
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