I'm trying to determine how many watts of lites I have on my layout to install the appropriate wiring and switches. Manufacturers don't seem very helpful when describing the lites in their accessories. For example, the Lionel highway lite, 6-12804 is described as an 18 volt bulb even when I ask Customer Support, that is all they know...no mili amps, watts ...nada. Same with the bulb in the Microwave tower, a 12Volt bulb.
I sure there is a convesion table out there that lets me convert volts and amps to watts, but I have not been able to locate one.
When I try to use the formulae and calculate that pertain to the Watt calculation, I get ?? results.
A 12 Volt bulb at 10 Amps [the equivelant of a PW ZW] yields a Resistance of 1.2 ohms
When the amps are multiplied by the resistance, I get 12 watts, the equivelant of the volt rating. Same for 18 volt bulbs.
Does this mean that a Volt rating is a Watt rating? or have I misapplied the formula or used the incorrect ones?
thanks for helping
Ralph
ONE way of finding an answer would be to use the "Search our Community" function to the right of your post. Try this:
1. Enter anything, such as 'lamp" and hit Search.
2. Ignore results for the moment, but scroll to bottom of page.
3. Hit "More Search Options"
4. In "the Find results with all the words" field type in "watts" without the quotation marks.
5 In "Matching all tags" type "lamp" without the quotation marks
6. In "Written by" type "lionelsoni" without the quotation marks.
7. In "Date" field select all.
8. In "Sorted by: select "Relevance"
9. Hit the "Search" prompt and browse the results.
There are many, many variations on this technique, including different authors, but if you can't find what you need under "lionelsoni" I'll be surprised. He continues to monitor this forum, so you can always direct a specific question to him.
One thing to keep in mind is that operating a lamp at a voltage higher than its rating will quickly burn it out. Some modern train-power systems put out a constant 18 volts or so. These may require that you exchange a lamp for one with a higher rating.
Sometimes you can get useful information simply by keying-in a lamp's number into Google.
We tend to call them "bulbs," technically they are generally referred to as "lamps."
Remember also that pre- and post-war transformers were usually rated at their input power. The power that they could deliver continuously was typically about 60% of the value at which they were rated. Many modern transformers will deliver their rated power. Quick and dirty: If you can ascertain the current-draw (In AMPS) of each of your lamps (under your operating conditions) you can simply add them up and compare the total to the rated amperage that your power source can pass through before its fuse or good-working circuit breaker pops.
The amount of power required to illuminate a layout is frequently greater than one might suspect.
Due to their lower power draw, you can drive a whole lot more LEDs with a given transformer than you can incandescent lamps.
.
Ralph, I think your problem is that you are multiplying the lamp voltage by the transformer's rated current (or what you think its rated current is--the ZW's circuit breaker trips at 15 amperes). The power that a lamp consumes is the voltage across it multiplied by the current through it.
A toy train transformer acts (approximately) as a constant-voltage source. The current that flows is determined by the load(s). So, a transformer set to 14.4 volts but without any load connected puts out 0 amperes of current. 14.4 times 0 is 0; so it is putting out 0 watts of power. Now suppose you connect a number 53 lamp to the transformer. That lamp is rated to draw 120 milliamperes of current at 14.4 volts, and it will. Now the power put out by the transformer and consumed by the lamp is 14.4 * .12 or 1.728 watts, even though the transformer is capable of putting out much more power than that.
Each load that you connect draws a current that depends on its own characteristics, while the transformer supplies the sum of those currents. Each load consumes an amount of power that is the product of the transformer voltage, which is also the voltage across the load, and the current that the load draws at that voltage. So you can add up the load currents and multiply by the voltage to get the power that the transformer is called upon to supply. Or you can multiply each individual load's current by the voltage to get the power that it consumes, then add these up. You should get the same answer either way.
Let me warn you not to assume that Ohm's law applies to every load. It applies only to resistors, which is kind of like saying that it applies only to those things that it applies to. In particular, don't use it with incandescent lamps. The current that they draw is not proportional to the voltage across them, which is the definition of a resistor. For a lamp, you either have to run it at its rated voltage in order to know what current it will draw, that is, its rated current, or you can use an approximation to estimate what current it will draw at some other voltage. But you can't assume that the current will be proportional to the voltage, as Ohm's law would tell you.
Bob Nelson
Ralph,
Volts and watts are two differant things. Basically volts is the applied electricity(like 12 or 18 volts), watts is the amount of power used by something, amps is a type of power rating(measures the flow of electrons or potential output), usually applied to circuit breakers or fuses, and wire sizes. The term miliamp means a milionth of an amp, usually used in electronic work.
It is probally more complicated but at least you can get a better understanding of electrical work and terms.
Lee F.
Voltage is also called "electromotive force" or "EMF" or "potential". It is like electrical pressure. Current, measured in amperes, is, as Lee says, the flow of electrical charge (not necessarily but usually electrons), but I would avoid calling it "potential", which, as you see, is used for voltage. A milliampere is one thousandth of an ampere, not one millionth.
Do you guy's know if you can wire up a strand of those small christmas tree lights to a transformer, such as you may string out along a christmas village, especially the LED type chrismas lights??
The reason I ask that is, often we all wind up with way too many of those left over around the house, and for those of us who like to build stuff, you could make a whole lot of street lights out of a set of those. But would it run off of a transformer, if you stripped the end off it, and hooked it to the transformer??
You can; but you need to adapt the string to the transformer voltage. Those strings are meant to be run at 120 volts; so you have to chop the original string into chunks suitable for your transformer voltage. For example, if a series string has 50 lamps, each lamp is getting 120/50 = 2.4 volts. If you want to run from a 12-volt transformer, you need to use a series string that is 12/2.4 = 5 lamps long.
LEDs are more problematical than incandescent lamps. If they have a ballast in series with the string, all bets are off. But otherwise you can probably divide them up the same way. However, since they conduct current in only one direction, you should have as many (smaller) strings conducting in one direction as in the other, so as not to saturate the transformer. That may be tricky for an electrical novice to get right.
When figuring out how many lamps are in a series string, keep in mind that a single set may have more than one series string; and an LED set will almost certainly have an even number of strings. You'll have to trace the wiring carefully to be sure you're counting the lamps correctly.
I would also assume you would not want to run the string of lights on your train platform plugged directly into the outlet because you really don’t want 120 volts running because of the risk of fire and shock potential?
Harold
magnum2230b Do you guy's know if you can wire up a strand of those small christmas tree lights to a transformer, such as you may string out along a christmas village, especially the LED type chrismas lights?? The reason I ask that is, often we all wind up with way too many of those left over around the house, and for those of us who like to build stuff, you could make a whole lot of street lights out of a set of those. But would it run off of a transformer, if you stripped the end off it, and hooked it to the transformer??
The only problem with having something in series; like lighting is when one bulb burns out, unless this problem has been overcome with small electronics, all the others go out as well. Sometimes those little christmas lights will burn quickly, you have to know what voltage to use with them!
What I have done is to use small light bulb sockets(RS part # 272-357) from Radio Shack with light bulbs from either Radio Shack(RS part # 272-1127, 14.4 volt) or your local hobby shop and use an older Lionel small watt transformer to power them with. Then I connect them with AWG 16 wire in parallel, you can run about 8 to 10 lightss on one transformer.
One thing that wasn't mentioned for the LED lighting is current limiting! You MUST limit the current with either a constant current source or usually a simple resistor, or those LED's will have a very short life, like about half a second!
That would be the ballast that I mentioned. It is possible to operate LEDs without a ballast if their voltage and the like voltage are carefully matched. Some LEDs are also packaged with individual ballasts.
Well, the knee between max current and meltdown of an LED is very small, so operating them with no current limiting is foolhardy IMO. I wasn't sure what you meant by ballast, not a normal term for me when dealing with LED's.
I agree with you that constant-voltage operation of LEDs is flaky; but I've seen it in consumer electronics like flashlights and Christmas-tree lights.
http://en.wikipedia.org/wiki/Electrical_ballast
Note that your ballast reference speaks primarily to florescent lamps, which is where the term is normally used. I agree it's technically correct for LED's, just not a term in general usage in that context.
As far as constant voltage operation of LED's in the train environment, not much is "constant" as far as voltage in the train world, so I still say that's a really bad idea.
Wow, a lot of good input on this post. I thought it might be a good idea at the time, but I guess I will stick to some other form of layout lighting in the future for my project. In light of all the good information here, it just sounds a little too iffy to work with any real confidence, and all the wiring may leave time better invested in something else that is at least tried and proven to work.
Thanks for all the replies, and all the good input......dave.
Well, LED's are proven to work and they work very well. They have a huge benefit, they use very little power for the light output. Normally incandescent bulbs are overkill for most lighting chores on a model RR layout.
I recently had a discussion about powering 30 022 switches on a layout with a KW 190 watt transformer. Turns out with conventional bulbs, that isn't possible! You actually will use more than the transformer can supply lighting the 60 bulbs, 30 in the switches, and 30 on the controllers!
Actually, using number 53 lamps, you would need 104 watts at 14.4 volts, 147 watts at 18 volts, or 77 percent of the transformer rating. That's not to say that LEDs aren't a better choice, although salvaging them from Christmas-tree lights as was proposed does require some engineering.
lionelsoni Actually, using number 53 lamps, you would need 104 watts at 14.4 volts, 147 watts at 18 volts, or 77 percent of the transformer rating. That's not to say that LEDs aren't a better choice, although salvaging them from Christmas-tree lights as was proposed does require some engineering.
The KW is rated "to supply continuously approximately 140 watts of useful power, or approximately 10 amperes of current, at normal operating voltage. The circuit breaker which protects the principal circuits is set to carry that amperage." If your breaker trips supplying 150 watts at any voltage over 15 volts, then your breaker is out of specification.
Well, in my test I cranked it up to 12 volts with two of the four of the 4 ohm resistors in parallel across it. So, I guess that was about 12A, I only have a 10A capability with my meter, so I was going on the resistance.
The bottom line here that has been missed in all the calculations is that it takes a lot of power just to drive the lamps of a bunch of switches. Also, the switch controllers don't use a #53 bulb, and the older 022's use a 1445.
I may have misunderstood the test you did, if so I apologize. As described there was two 4 ohm resistors in parallel across a 12v source; that is two ohms with I=E/R yielding 6A. If the resistance loads are accurate then it indicates the breaker in the transformer is tripping prematurely and may be defective. I wonder if the 60 Hz impedance of the audio test loads are actually 4 ohms. If the 4 ohm impedance rating is at a higher frequency then the current draw at 60HZ could be correspondingly higher.
Tom
Two 4-ohm resistors in parallel are 2 ohms. Twelve volts across 2 ohms is only 6 amperes. So I think your circuit breaker might need some attention.
I was responding to your assertion that it wasn't possible to power 30 turnouts with a KW, by giving an example of how it can be done. Number 53 lamps are an improvement over 1445s (which were used in later 022s, not earlier ones) as far as power consumed and heat generated are concerned. And their screw-base counterpart, number 52, is even better as a replacement for the 1447 or 432.
(I realize now that my numbers should be about 1/12 lower, since the 022C lamps at least would have to be replaced by the number 52, not the 53.)
I revisited my test, the breaker actually trips at 8A after about 10 seconds running at 12V. It does seem to have a small issue, I'll probably replace it with a 10A automotive type, much cheaper than the obsolete ones that come in those old transformers.
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