halogen 12v, i never knew this and am now stuck

[rwalton1]

Have 2 mr11 halogens in parallel on circuit with transformers above each bulb. Neither are working, despite changing and testing bulbs in circuit nearby. With neon screwdriver i was surprised to see both the blue and brown wires out of transformer were live. (as they were on the working circuit) and then using a voltmeter got a negligible reading. I guess there could/ should be voltage in both and the potential is just minimal, Anyhow very strange to have both in same circuit and therefore very unlikely to be a transformer issue.

Any clues?

 

[Spark123]

Are GU10 lamps not mains voltage? Don't use a neon screwdriver to do any testing, use a volt meter / multimeter.

 

[rwalton1]

you are right mr 11 sorry

 

[Spark123]

If you test across the input to the transformer L&N with the power in with a multimeter set to VAC on a range in excess of 250v what reading do you get? Be carefull not to touch any live parts.

 

[rwalton1]

240ish

 

[ban-all-sheds]

I guess there could/ should be voltage in both and the potential is just minimal

Voltage and potential are the same thing...

What measured voltage do you get on the output?

 

[rwalton1]

Voltage on out put minimal <1v; i am no electrician obviously! but i always thought potential was difference between two voltages, one is normally zero, but does not have to be

 

[electronicsuk]

Voltage on out put minimal <1v; i am no electrician obviously! but i always thought potential was difference between two voltages, one is normally zero, but does not have to be

How else can you measure voltage without a point of reference? It always has to be between two points.

 

[ban-all-sheds]

Voltage on out put minimal <1v;

That'll be why the lamps aren't lighting up then.

i am no electrician obviously!

Even so, how hard is it to connect L&N to the input of a transformer?

Have 2 mr11 halogens in parallel

You are absolutely sure you've connected them in parallel?

 

[slup]

Hi

Most electronic transformers won't output anything meaningful without a load connected. Also, they are high frequency which a multimeter often cannot cope with.

Steve

 

[rwalton1]

Thanks steve, yes i read that output is 44khz vs normal 50hz. So that makes sense why i got no reading and perhaps why i picked up both were live with neon as that is a load? I will try changing both transformers just in case there was a systematic problem with the location that has damaged them.

 

[ban-all-sheds]

and perhaps why i picked up both were live with neon as that is a load?

No - it isn't a load - it lit up because they light up for all sorts of reasons.

You could probably make it glow by rubbing it on a nylon carpet.

 

[rwalton1]

anything that draws a current is a load aint it?

 

[Spark123]

In order for a current to flow you need a potential difference.
A neon is a load however it requires a very small current to flow through it to get it to illuminate. I can't remember the exact figure you need to get a neon to strike - think it is around 70v but after that to sustain it will be smaller.
This potential difference required to cause the current to flow through the neon can be created from a whole manner of different sources, once you start using yourself as part of the circuit there is a whole range of different paths.
As BAS says rubbing on a carpet may create enough static to enable a neon to light - never tried that one.
One thing I do know - using yourself as part of the circuit (which is how a neon screwdriver works) is not a good idea.

 

[rwalton1]

i see what you mean but these electronic transformers; how do you pick up a reading? have you tried? since the multimeters obv dont work