Electrical gurus please - neon question

[tbourner]

I heard that neons sap power unless you use a relay.

 

 

Is this true?

How would the relay be wired in?

 

I'm guessing battery through switch to relay terminal, then out to transformer, then back to battery.

Other side of relay cuts in the neon cabling somewhere.

????

 

Or is it 2 seperate circuits? ie:

Neon transformer constantly plugged onto battery, switch then connects to battery and relay, other side of relay is still on neon cabling somewhere?

????

 

Which relay to use?

 

 

 

 

No replies consisting of 'Why are you getting neons?' please! It's not what you think.

[Dragonball]

Dont get Neons - get LED's (Varad make the best!)

 

These have much less 'draw' and last longer / brighter etc

 

[tbourner]

Yeah I know, but I already got some Neons.

 

They're not for under car so it doesn't really matter, I'd definitely get LEDs under car if I ever did.

[merckx]

Using a relay won't make them use less power.

 

The relay is used to switch on high power circuits.

 

You can buy 40 amp automotive relays at most car accessory shops.

 

 

You do have 2 circuits.

 

Circuit 1. relay coil

 

Circuit 2. 40amp switch on relay

 

I could tell you exactly how to do it in detail. But If your not sure I think you would be better off asking someone who has done this sort of thing before.

 

You would't want to f*ck anything

[tbourner]

I thought that, I just heard from someone who had put neons in that the lights dimmed when he switched them on, and a relay would help.

 

 

Maybe I'll just plug 'em in first and see how it goes - I've only got 2 tubes so I'm guessing they'll draw less current than 4 tubes.

 

How come the instructions say to put all the tubes in series though? Are they rated for a large range of voltages? It won't matter if I've only got 2 and they're meant for 4 will it?

[merckx]

Don't know anything about neons.

 

But if it recommends 4 neons in series and you use only 2 you will be putting too many volts across them.

 

Had a quick look on Google, some have external transformers(must mean they don't use 12v dc).

 

You would have to see what the neons are rated at.

[tbourner]

It doesn't say, but surely you can put just 1 neon on a transformer? I've seen cas with 1, 2 3, and more neons on them.

 

The trasformer's O/P voltage is 9500 (30mA max).

 

Is voltage common in parallel? I can't really remember much from my HNC electronics (even though it was only 2 years ago - it's easily forgotten!!). So the 9500 volts is (roughly) split between how ever many neons you have in series? What a stupid system.

 

Surely they wouldn't be sold like that with minimal instructions if it wasn't safe to do? Why not just plug them in parallel (as long as the transformer can source enough current!!)?

[Digsy]

For loads in series, each load will have a proportion of the supply voltage dropped across it. For dissimilar loads the proportion of volts dropped will be the same as the proportion of the load impedance. The sum of the voltages dropped across all the loads will equal the supply voltage. All loads will see the same current.

 

For loads in parallel, all loads get the same supply voltage. Each time you add another load in parallel the overall load impedance drops and more current is drawn from the supply.

 

So if you keep adding loads in series they will just get dimmer and dimmer until they don't work because there simply aren't enough volts to "go around". But if you keep adding loads in parallel eventually you will blow up the transformer because you are asking it to supply too much current.

[Digsy]

I just realised. I'm giving advice on fitting neons

[Ian C]

 

-Ian