How to light 220v bulbs on from low Vac

[Freaktron]

New newbie (electrondummie) here:

How can I can turn a 220v light bulb on from a low Vac. My guess is by using relays. Can anyone share a circuit?

Thanks!

 

[Willbe]

My guess is by using relays

Or a step-up transformer.

 

[silvarblade]

there are a lot of relays available that work on 110Avc and can switch 220v ac.it would be more easy to answer if you specified the voltage that is going to switch it.

 

[Hero999]

What do you mean by low voltage AC?

220VAC is a low voltage.

 

[Freaktron]

there are a lot of relays available that work on 110Avc and can switch 220v ac.it would be more easy to answer if you specified the voltage that is going to switch it.

I have a device wich has a terminal barrier where I connect the 110v pair. The other terminals are to connect the light bulbs - when a certain switch is turned on - through the already existing relays the bulbs lighten on. What I want to do is avoid the use of 110v and replace them with low Vac to trigger an outside relay - instead of bulbs - and then place the bulbs. What relay should I use for this purpose?

 

[Freaktron]

What do you mean by low voltage AC?

220VAC is a low voltage.

Lower than that... up to 30 Vac

 

[Hero999]

Do you want to power it from 30VAC or control a 220VAC using a 30VAC signal?

To power it you need a step-up transformer which can be a normal mains transformer connected backwards.

To control a 220VAC circuit, you need a relay.

 

[Willbe]

I have a device wich has a terminal barrier where I connect the 110v pair. The other terminals are to connect the light bulbs - when a certain switch is turned on - through the already existing relays the bulbs lighten on. What I want to do is avoid the use of 110v and replace them with low Vac to trigger an outside relay - instead of bulbs - and then place the bulbs. What relay should I use for this purpose?

Can you post simplified before-and-after schematics? English is an OK language but "schematic" is a perfect language.

 

[Freaktron]

Here they are

 

[Phasor]

Here they are

Ok, so what you need is (as has been mentioned already) a step-up transformer, as you need to generate the higher 220V from your 30V supply.

Something like this, wired in reverse, should work.
**broken link removed**

 

[Willbe]

Ok, so what you need is (as has been mentioned already) a step-up transformer, as you need to generate the higher 220V from your 30V supply.

But
first check that the 30 V source can put out enough power for the 220 V bulb,
and
if the bulb does not pull rated output current from the transformer the voltage will climb above 220 V
and
then incand. lamp life of a 220 V bulb at 250 V = (100%)(220/250)^12 = ~20% of normal. Brightness will be 100%(250/220)^(3.5) = ~160%.

If any of the above is not true, it's relay time!

 

[silvarblade]

sorry didnt sign in regularly!

a stepup Xformer would work as advised by many if you have got enough power in your source(thanks willbe).i said relay because i thought that a 220v lamp means a 220v mains and that would be feasible to use with a relay cause he can get 220v easily!

By the way what currents are we talking about?

 

[Freaktron]

Thank you guys!

I found an easier way... I got an old 220-10v ac/ac transformer and hooked it to the relays. I joined 4 leds in series and connected them as I would do with the light bulbs. It worked fine!

 

[Hero999]

if the bulb does not pull rated output current from the transformer the voltage will climb above 220 V
and
then incand. lamp life of a 220 V bulb at 250 V = (100%)(220/250)^12 = ~20% of normal. Brightness will be 100%(250/220)^(3.5) = ~160%.

If any of the above is not true, it's relay time!

If it's a 220V mains transformer being used in reverse, that won't happen.

The voltage will be lower than the rated primary voltage. For example I have a 230V to 230V isolation transformer. When 230V is connected to the primary, the secondary voltage is about 250V but when 230V is connected to the secondary, the output voltage is just 210V. I haven't tried operating the transformer with a load in reverse but I think the output voltage will drop to around 190V.

If he wants the transformer to outpur 220V when connected to a 30V load, then he needs to use a transformer that outputs just under 30V when unloaded, a 24V transformer will probably do the job.

 

[Willbe]

When 230V is connected to the primary, the secondary voltage is about 250V
when 230V is connected to the secondary, the output voltage is just 210V.

250/230 = 1.087
230/210 = 1.095
If you only consider two significant figures (1.1) these numbers are equal. So far, no blatant violation of the laws of physics.

So, what I said is true half the time!? Those odds are lousy. If this keeps up I"ll have to run for political office. . .

 

[Hero999]

That's true, isolation transformers normally have more turns on the secondary than primary so the secondary voltage approximately equals the primary voltage at full load.

In this case the turns ratio is 1:1.1.

You might think a 240V to 24V transformer would have a turns ratio of 10:1 but it doesn't, it more likely to be 10:1.1.

 

[Ubergeek63]

or 10:1.2 if it is small since most smaller transformers have a 20% regulation rating