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Discussion Starter · #1 ·
I picked up these lights but cannot figure out what the voltage is. The amperage is indicated as 20mA as a set, but that's all I can find. All I had was a 18v out from my transformer and while testing one of the lights, it instantly blew.

Are these typically 12v? Less? Thank you.

ALSO, unrelated question: once I figure out the correct voltage, should lights be wired in series or parallel?

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Discussion Starter · #2 ·
I took a second look at the transformer. Seem the accessory output I used was AC 18v. The output for the trains is 4-18v DC. I put the other (working) light on the DC side and it lit up fine.

Are these lights DC only?
 

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Yard Master & Research
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The product is from Woodland Scenic. They make a light Hub and a Power supply. From reading, it should all just plug in together. The Hub would be in parallel. The Power supply said 16 volts AC. WIth that information they should work on AC accessory power. I have no idea why the light set blew up, 2 volts over must have been too much. Also the light hub each port is adjustable. Try a three volt battery combination for one light set.
 

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Bulbs don't care if they are fed AC or DC, only that they aren't over-volted. 12-16v is what I would guess their working voltage is. They are only going to draw whatever current they need.
 

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I was wondering if all of the resistance was in the Hub connection. This is a buy and plug in setup. They are LEDs.

It would not hurt to run them on DC. You could dismantle the broken one to see if it contains any resistors or diodes?
 

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Discussion Starter · #9 ·
The lights with battery packs are easier. Two batteries 3 volt or three for 4.5 volts. 12 to 14 volts should work.
I have a box of old wall warts downstairs. I'm sure I have a 12V one. How many amps do you think is enough? I may plan to run about a dozen-ish lights. Also, should the lights be ran in series or parallel? Thanks again.
 

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It has to be parallel. If the voltage was 24 volts then two could be placed in series. If they are wired for AC polarity will not matter. If the adapter is rated at 1 amp, technically it can run 50 LEDs. Like anything else there is a voltage drop. I have not pushed an adapter to the max.
 

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Did you read the package? It has right on front "20mA SET".
To supply the 20mA, divide 18 volts by .020 amps yielding 900 ohms.
Connect a 900 ohm resistor to each bulb.

Does the plug have two leads or three?
You need to open up the burned out light and find if they are two bulbs in series or parallel.
 

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Too much guessing and speculation...need to test.

T-man has the best suggestion for safest testing for
the voltage of your lights. Notice that there
are two 'bulbs' per lamp post. Possibly 1.5 or 2 volts each.
Use 1 Battery (AA or AAA or C or D)=1.5 volts.
and see how the lights glow...reverse battery terminals
to change polarity...if low glow...use 2 Batteries in
series = 3 volts...if glow is bright...3 volts is appx. the DC voltage
you need for EACH lamp post...if you connect two
lamp posts in series you would need 6 volts...etc.
Two connected parallel you would need 3 volts.
Observe polarity.

Don
 

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It plugs into what and what the output of the thing it plugs into. Seems like that would answer the question. Or is whatever it plugs into not have any public specs?
If it is a "wall wart" then there SHOULD be a label stating input voltage (110VAC) and output voltage (maybe 4.5VDC). Not sure if this labeling is a UL and international requirement but every wall wart I have gives a clue to output voltage type and sometimes amperage. My two pennies.
 

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People who use the product do not look at specs. LED and plug in . It is made to be a stand alone system you can add with no fuss or worry. It depends on what you want to spend your time on. I remember 20 years ago it was hard to find information on an LED and figure out how to use it.

You always replace the LEDs for the broken lamp. Heck with some brass tubing you can roll your own.
 

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LEDs are current sensitive which is why the 20mA (0.020A) rating. Resistors provide current limiting. If, say, a 2.6 volt LED is connected without a resistor across just 3 volts they can burn out quickly if no resistor.
A 1,000 ohm potentiometer (pot) would be handy as well as a resistor assortment. If it's connected as drawn (9 volt battery is fine, series a 100 ohm resistor to pot (center "wiper" to either end), then through a multimeter on current range you can turn on led, adjust pot for 20mA. Disconnect pot, measure that resistance then add in the 100 ohms. Say it's 500 ohms total...then use a resistor that value or close...measure current again to verify 20mA. Lower current LED isn't as bright but will last longer.
If LED doesn't light, reverse it...it only lights one way, reversed won't harm it.
PS= power supply
M= meter
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