230v to (around) 12v in smallest/simplest form

[MikusP]

Hi!

Working on a simple project using resistance wire in varying lengths. At the moment I'm directly connecting this to a 9v battery and it heats up pretty well! Looking for a way to run this directly off the mains. I know energy saving CFL bulbs use tiny transformers to reduce the voltage. Would it be safe to rip one of these appart, remove the transformer and connect it directly from the mains to the wire?
Recipe for disaster?

Thanks for any help.

MikusP

 

[Maverick]

NO, that simple, if your not sure what your doing then don't do it whenever mains potential is involved.

CFL transformers actually step the voltage UP not down to ionise the gas inside them, so it sounds like your heading for a world of hurt.

I suggest you get a voltage and current limited bench-top power supply from maplin or somewhere if your a beginner.

I am a fully qualified EE and have worked on everything for 0 volts to 66,000 volts (and were talking power-line switchgear 66KV) and still prefer to stick to 12v or below.

 

[MikusP]

Thanks a lot Maverick.

Not the answer I was hoping for but definitely some sound advice. Think I'll have to do a bit more research on this one.

Thanks again.

 

[jackorocko]

Well what are your current requirements and what is 'small'?

As maverick says though, you are playing with a serious shock hazard with mains voltage. It can be a deadly game. Know what you are getting yourself into.

 

[MikusP]

Hey jackorocko,

Honestly not sure about current requirements. I'm using hand cut lengths of wire so I guess it might vary between each cut.

And as for small, I was hoping for something around the size of a film can. Might not be realistic tho.

And thanks again for the warning. My academic knowledge of electronics is fairly basic but, if it puts your mind at rest, I'd never come close to touching anything mains whilst powered.

 

[Maverick]

If your upto what i think you might be upto (my guess is a hot wire for cutting through polystyrene n stuff) your not going to get the currents required from something as small as a film can. Your best bet is a bench supply with a decent current capability. Or the cheap hacked PC PSU which can usually supply 25amps on the 12v rail but that output is fixed you will need to limit the current with a suitable power resistor.

If you explain what your doing exactly it might be easier to make safe suggestions

 

[MikusP]

Hi Maverick!

Thanks for the reply. Its actually for an experimental art project and all I need is for the wire to give off a small glow. Although its definitely generating some heat its not too important and its not being used in an environment where this could pose a danger. So far the 9v batteries have been giving me enough power to create the effect I'm looking for and I'm just looking to replicate this on an easily repeatable scale.

 

[Maverick]

What for can you describe what it is there are alternatives to a length of red hot wire to produce a glow that don't have the inherent fire risks.

For example have you considered electroluminescent wire ? this can be run off a battery or small wall adapter with a suitable inverter easily and although it's high voltage it is high frequency and very low current so pretty safe and doesn't get hot at all.

If your determined on hot wire and your getting the effect at 9v then a high current switch-mode psu will do what you want.

If its just a glow your after the EL wire is a safer all round and easier to implement bet

 

[CocaCola]

In addition to the EL wire suggestion...

May I suggest side light (make sure it's side light not end light they are differnt) fiber optics instead of the huge power drains of a resistance wire? Get a section of stranded fiber cable (note diameter of strands you want) Using a single strand of side light fiber optic, you can take some clear epoxy and glue the end of the optic strand to the head of an amber LED, paint the LED and connection point black so that there is no light leaking and you get a glowing amber strand... Is a hot knife to cut the ends of the strand to get a clean 'clear' cut that will better transfer the light from the LED to the strand... No heat, no worries and low power consumption...

Link to a random Google hit...

http://www.fiberopticproducts.com/Sideglow.htm

Pull down to the stranded stuff on that page and you can see you get a bundle of .75mm strands for $3.85 ft