According to Walthers the bulbs use 30 ma but they recommend strongly that I NOT use a 16V power supply as it will "Cook the bulbs" so I guess I'll do what several have suggested and use a 12V supply
I agree with the 75 percent suggestion. I have used that for many years and stayed out of trouble.
Rich
If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.
The 200ma (marked 200m) on the HF meter will be sufficient to measure a single street light. There is a 10A range that requires moving the test lead to a different socket on the front fo the meter, but it won;t be accurate enough for just oen street light that is 30ma or less.
Once you figure out the current for one, if you wire them in parallel, the total current will be the sum of each one - so if one light is 25ma, and you connect 10 of them, youw ill need 250ma total power to drive them all.
Good rule of thumb, similar to house wiring, is never go above 75% load on the power source. So to supply 250ma you would want a power supply rated at around 330ma. But anything larger is fine - 250ma worth of lights will draw 250ma regardless if connected to a 300ma, 750ma, or 2 amp power supply. You can;t 'push' amps. Voltage matters, for incandescent bulbs. If the street lights are rated for 16V, you would bet better off runnign them at 12V, they will not be so glaringly bright plus the lights will last signficiantly longer than if run at their rated voltage.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
MisterBeasley Pretty much every meter I've ever seen will read Volts, Amps and Ohms. They have knobs to select the scale, so you can set it to read hundreds of volts or fractions of a volt. To measure current, you must put the meter in series with bulb. That is, power supply to meter, meter to bulb, other side of bulb back to the power supply. For voltage, you would connect the bulb to the power supply normally, and then measure the voltage between the two bulb wires.
Pretty much every meter I've ever seen will read Volts, Amps and Ohms. They have knobs to select the scale, so you can set it to read hundreds of volts or fractions of a volt.
To measure current, you must put the meter in series with bulb. That is, power supply to meter, meter to bulb, other side of bulb back to the power supply. For voltage, you would connect the bulb to the power supply normally, and then measure the voltage between the two bulb wires.
Since you might be new at using a multimeter, start out at the max current scale and work your way down.
Too much current on a low scale and a small fuse in the meter will blow. You can get the replacement fuse from Radio Shack. Two screws to open the meter and they use a common 9 volt battery.
One down side of these cheap meter is the fact they do not measure AC current. Only DC current. I never use AC current for lighting, only DC.
I have three of these meters for sometime.
Harbor Freight also has a nice clip lead set. Just don't let the clip lead tips short against another clip lead.
Hello Mister Beasley, thank you for the infos.
Serge
It takes an iron man to play with a toy iron horse.
Hello Randy, thank you for the infos, it's greatly appreciated.
The cheapest one. It's listed on the site for $9.99 but is usually available on sale for $4-$5.
For anything but precision electronics, it's plenty adequate, and that's comming from an electrical engineer. These thigns are great for basic model railroad and most any other use the average person would have for a meter.
Hello Mister Beasley, in your reply to Dadret you mentioned using a Meter.
Can you elaborate a bit on that subject, I went on "Harbor Freight Tools" web Site and I'll be honest with you I wouldn't know which model to buy.
Thank you.
I don't have a rating for these, but typical 16-volt incandescent bulbs (Miniatronics) run about 30 milliamps. If you don't have a meter, by the way, it's a very good investment. Harbor Freight and similar stores have them very cheap.
I also would recommend running these at a lower voltage. I have a lot of Walthers Cornerstone streetlights, which are rated at 16 volts. I run them at 12 volts. I prefer the lower level of light anyway, and by running them at well below their rated voltage I hope to greatly extend the bulb life.
I thought about that and may end up doing it - I like the wall warts because they don't take up much room and I don't have to find a place to put the power pack.
Just a suggestion: Instead of using a wall transformer to light your street lamps, you could use the DC terminals of a spare power pack. This will allow you to "adjust" the lighting and, thereby, extend the life of your street lamp bulbs dramatically. You then don't have to know what the amperage of the bulbs are.
I typically operate my interior and exterior incandescent bulbs @ 55-60% capacity with a MRC 1370 Railpower power pack. At that level they still emit a very nice glow but it's not too bright:
dadret, if you are intent on using the wall transformer, I would contact Walthers directly and ask them how much current those particular street lamps draw.
Tom
https://tstage9.wixsite.com/nyc-modeling
Time...It marches on...without ever turning around to see if anyone is even keeping in step.
So thats what happened. I did upgrade to IE9 and this isn't the first problem I've had since I did. What the original post should have said: "Does anyone know how many milliamps each of the Life Life Street Lights (Walthers Catalog 433-1254) draws? I'm going to hook up several to a 16VDC 900ma wall transformer and need to know how many I can safely hook up to each transofrmer. The lamps are 14-16V AC or DC but I can't find the ma rating of each bulb."
Not sure what you're asking, dadret. However, I can probably guess that you've upgraded to Internet Explorer (IE)9 recently.
In order for your post to become visible, you need to click on the torn paper icon up at the top of the page and to the right of the URL (web address) box. This will run a compatible version of IE8 so that your browser and the forum software can play nice together. You'll also need to re-post your inquiry either in your original post or as a reply in this thread.