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Wiring 1.5v lights

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Wiring 1.5v lights
Posted by Santa Fe all the way! on Tuesday, April 6, 2010 6:32 PM

How do you wire 1.5v lights to the accessory side of a cheap transformer from a train set. I have several of the old cheapo train set transformers, so I thought Id use them for my lighting. If you know a better way, let me know.

Come on CMW, make a '41-'46 Chevy school bus!
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Posted by jerryl on Tuesday, April 6, 2010 6:43 PM

 You are probably going to get at least 16 volts from the acc. output. You would have to wire them in series to keep them from burning out. I would wire at least 16 in series to give each bulb about 1 volt. They will be a little dimmer  but will last a lot longer. I put a 14 volt bulb rated at 6hrs in a 12 volt aquarium light & it's been burning continuously for almost 2 years so far.    Jerry

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Posted by superbe on Tuesday, April 6, 2010 7:10 PM

I have the same question as the poster. I can understand your answer, but what if you are just starting out and only have 1 or two lights which is my situation?

Bob

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Posted by Medina1128 on Tuesday, April 6, 2010 7:39 PM

jerryl

 You are probably going to get at least 16 volts from the acc. output. You would have to wire them in series to keep them from burning out. I would wire at least 16 in series to give each bulb about 1 volt. They will be a little dimmer  but will last a lot longer. I put a 14 volt bulb rated at 6hrs in a 12 volt aquarium light & it's been burning continuously for almost 2 years so far.    Jerry

 

The problem with wiring bulbs in series is the same with the old Christmas lights wired in series; when one burns out, it's a real pain to find out which one it is. I'd put a heavy duty resistor in the circuit to drop the voltage down to 1.5 volts, then run the bulbs in parallel. You will have a resulting drop in current (amperage), but it's better than pulling your hair out finding one bulb. Personally, I agree with Jerry; use a higher voltage bulb and keep the voltage below that rating.

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Posted by steemtrayn on Tuesday, April 6, 2010 7:47 PM

If you need the power supply to run trains, then get another cheapo and connect the lights to the variable DC terminals. Turn up the dial, stopping just before the bulbs burn out.

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Posted by Texas Zepher on Tuesday, April 6, 2010 8:19 PM

Santa Fe all the way!
How do you wire 1.5v lights to the accessory side of a cheap transformer from a train set.

Several things.  The first thing you need to know is how much voltage the transformer is putting out.  Then there are several ways to do it.

1.  Wire them in series to consume all the voltage.  That is if it is producing 16V then you would need 11 lamps wired in series 1.5V * 11 = 16.5V.   Or better yet throw in another one and run the bulbs at less voltage than they are rated at.  That will make them last much longer.  1.5V * 12 = 18V.   I try to run 1.5V bulbs at 1.2V each.

2.  Measure the current draw of each bulb and put a resistor in series with it.

Using the same 16V example.   16V - 1.5V = 14.5V.   If the bulbs are drawing 30ma. Then R=E/I  or R = 14.5V / 0.03A =  484 ohms.   Since I run bulbs lower 16V - 1.2V = 14.8V.  or 493 ohms.   In this instance I would get 500 ohm resistors.   Just remember this ohm value  is dependent on the current draw of the light bulb.

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Posted by PRRT1MAN on Wednesday, April 7, 2010 3:48 PM

Texas Zepher

Santa Fe all the way!
How do you wire 1.5v lights to the accessory side of a cheap transformer from a train set.

Several things.  The first thing you need to know is how much voltage the transformer is putting out.  Then there are several ways to do it.

1.  Wire them in series to consume all the voltage.  That is if it is producing 16V then you would need 11 lamps wired in series 1.5V * 11 = 16.5V.   Or better yet throw in another one and run the bulbs at less voltage than they are rated at.  That will make them last much longer.  1.5V * 12 = 18V.   I try to run 1.5V bulbs at 1.2V each.

2.  Measure the current draw of each bulb and put a resistor in series with it.

Using the same 16V example.   16V - 1.5V = 14.5V.   If the bulbs are drawing 30ma. Then R=E/I  or R = 14.5V / 0.03A =  484 ohms.   Since I run bulbs lower 16V - 1.2V = 14.8V.  or 493 ohms.   In this instance I would get 500 ohm resistors.   Just remember this ohm value  is dependent on the current draw of the light bulb.

This is the best way to do what you asked. IMHO

Sam

Sam Vastano
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Posted by steamnut on Wednesday, April 7, 2010 8:49 PM

Buy a full wave bridge rectifier,a variable voltage regulator, and the appropriate resistors and capacitors from Radio Shack. The variable voltage regulator package has instructions on how to calculate values and wire them. This will give you a steady 1.5V DC from your pack for a total cost of about $5.

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