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[SOLVED] How do I plug in a light bulb to the wall?

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vlor

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Hi, I want to hook some wires up to a small light bulb (LWSA301) and plug it into the wall. The light bulb was originally in a Maglite flashlight that took 3 D batteries. Can anyone help me out? What wires do I need and where do I attach them on the light bulb? I don't want to get shocked.

Thanks
Evan
 

You can not plug the bulb directly into a wall outlet, because the bulb works with 3.6 volts instead of 110 or 220 volts! You would need either a transformer or a DC power supply to interface between the bulb and the wall outlet. Looks like this:
Digi-Key - T1022-P5P-ND (Manufacturer - EPS050250UPS-P5P-KH)
 

When I look on my D batteries, they all say 1.5V, which adds up to 4.5V. How come you said it takes 3.6 volts?
 

Hi,
I think, he was assuming 1.2v instead of 1.5v, as there are many batteries rated at 1.2v especially rechargeable ones.

---------- Post added at 07:47 ---------- Previous post was at 07:45 ----------

What you need to do, is step down 220v/110v to 4.5v. This can be done very easily. Step down the voltage using a transformer. 220-6v. Rectify the output, you'll get around 9v. Add an LM317 circuit and you have 3.6v. If you could find a 3v transformer, then you can just rectify the AC and run it without regulator like LM317, but 3v isn't very common.
Another alternative, is use wall-warts that come with adjustable output, so that you can adjust the output. These are dirt-cheap and will do the job.
 

Hey Tahmid,

Would using this work?:

**broken link removed**

If it will work, where do I place each wire on the bulb after cutting it?

If that won't work, can you recommend a cheap wall-wart that is adjustable?
 

Hi,
This is perfect. The 4.5v output will light the bulb. The bulb has 2 wires and so does the adapter output. Just connect the outputs to the bulb, doesn't matter which way.

Hope this helps.
Tahmid
 
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    vlor

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Thanks!

Can I touch the wire/s while it is plugged in, or is that a no-no?
 

Yes, the two flexible wires coming off of the wall wart are low voltage. It is safe to touch them with your fingers. You should not let the two wires touch each other though, as that may blow out the wall wart.

In general it is safe to touch voltages below 30 volts. 60 volts and above are an electrocution hazard.
 

Yea, you can. Usually in a circuit if the output is low-voltage and isolated from the primary you can. Here the wall wart contains a transformer, so you can, but why take a risk? You should always take protective measures. If for some reason the transformer is damaged and becomes shorted to the primary, then you'll receive a nasty shock.

Hope this helps.
Tahmid.
 
Last edited:

Thanks guys! This was really helpful.
Also thanks for the tip about not touching the wires together, never would have thought of that.
 

While setting it up and while the wires are bare etc - DO NOT plug it in.

Simples.
 

Yea, have everything set up, check it twice or more if necessary, then only connect the adaptor to the mains. Don't leave any wires or connections bare, just tape it up.

Hope this helps.
Tahmid.
 

I did a quick test a few days ago - i plugged the adapter into the wall (while the wires were bare) and then held the rubber part of the wire while placing both of them onto the light bulb, and it lit fine. The wires were bare for a few seconds while I was getting ready to place them onto the bulb, why is this bad? Nothing bad seemed to happen.

Also, one more question, is it fine to just tape the wires to the bulb with electrical tape if I have nothing else to work with?
 

Hi,
Imagine if the wire mistakenly touches something else, maybe something connected to the mains, or if the transformer somehow gets damaged and shorted, it may give you a shock. Always stay away from touching bare wires when they carry current.
You can tape it if you have nothing else, but make sure it's tightly connected and isn't loose at all.

Hope this helps.
Tahmid.
 

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