Connecting 1.5v bulbs together

[MichaelT]

Morning,

Hope everyone had a wonderful Christmas.

I'm working on a scratch built small engine house for my shortline railroad, and I came across some 1.5 bulbs and thought it would be good to place them over the entrance doors for some outside lighting.

Is it possible to wire multiple bulbs together in series or should each set of wires go directly to the power source?

And speaking of power, what kind of power source should I use to illuminate these bulbs; I'm figuring with them being 1.5v will have to have a low powered source??

michael

[John]

if I remember my rules -

you will need around 3 volts to power them if you connect in series .. if you connect in parallel - you only need the 1.5v source ..

[DKS]

These bulbs are highly prone to burnout when fed with their rated voltage. I recommend placing several in series and powering them with a lower voltage, preferably pure DC.

Example: Use four in series, total of 6 volts at rated voltage. Power them at 4.5 volts.

A set of batteries makes a good power supply for these bulbs. 3 AA batteries in series will deliver 4.5 volts and they will last a long time. So will the bulbs.

As an alternative, consider using warm white 0603 SMD LEDs ("nano" LEDs) instead. They will out-survive the micro bulbs by many years. You can get them pre-wired with leads to save you the trouble of soldering very tiny parts.

Ngineering is an excellent source for parts and lighting kits: http://www.ngineering.com/n_lighting_kits.htm

[MichaelT]

Ok, so here is where I am with the lighting progress.

I have six total bulbs, each at 1.5v; I test wired them in series and connected the leads to a 9v battery. I have three bright lights, two very dim lights, and one light is not on at all.

So I connected the leads to a train controller, and got the same.

On a thought, I just took six leads from the bulbs and twisted them together, six other leads from the bulbs and twisted them together, hooked on bunch to one controller wire, the other to the other controller wire, and running the voltage up I have six bright shining lights.

So what am I missing? Seems when they're wired in series they're not pushing the power all the way through the circuit?

Thoughts?

[DKS]

Ok, so here is where I am with the lighting progress.

I have six total bulbs, each at 1.5v; I test wired them in series and connected the leads to a 9v battery. I have three bright lights, two very dim lights, and one light is not on at all.

So I connected the leads to a train controller, and got the same.

On a thought, I just took six leads from the bulbs and twisted them together, six other leads from the bulbs and twisted them together, hooked on bunch to one controller wire, the other to the other controller wire, and running the voltage up I have six bright shining lights.

So what am I missing? Seems when they're wired in series they're not pushing the power all the way through the circuit?

Thoughts?

Because of the way they are made, there will be variations in the performance of each bulb, which will tend to show up more when powered below their rated voltage. When you connected them to the train supply, you probably started pushing them over their rated voltage. At this point the variations in brightness will tend to even out; however, they also won't last very long.

You might try different combinations of bulbs with other power sources. Or, just use LEDs--they'll outlast the bulbs.

[MichaelT]

Because of the way they are made, there will be variations in the performance of each bulb, which will tend to show up more when powered below their rated voltage. When you connected them to the train supply, you probably started pushing them over their rated voltage. At this point the variations in brightness will tend to even out; however, they also won't last very long.

You might try different combinations of bulbs with other power sources. Or, just use LEDs--they'll outlast the bulbs.

Thanks David.

When you say different combinations of bulbs, do you mean connecting them together in different order?
LED's are on the list, but I wanted to use what I had on hand for now.

[DKS]

When you say different combinations of bulbs, do you mean connecting them together in different order?

No, the order doesn't matter. Just group them in bunches that behave similarly. For example, put the three brighter ones together in series and try powering them with 3 volts. Put the dimmer three together in series and try them on 4.5. You may need to try different combinations. You might also try powering the dimmer ones in parallel with 1.5 volts. They won't last quite as long, but avoid using your train transformer, as that's a sure way to burn them out fast.

[MichaelT]

No, the order doesn't matter. Just group them in bunches that behave similarly. For example, put the three brighter ones together in series and try powering them with 3 volts. Put the dimmer three together in series and try them on 4.5. You may need to try different combinations. You might also try powering the dimmer ones in parallel with 1.5 volts. They won't last quite as long, but avoid using your train transformer, as that's a sure way to burn them out fast.

OK I understand now. I guess I could just connect them all in parallel and run them off a AA battery for now.