Tranformer less power supply

[tech2000my]

I want to make 230AC to 110AC-180AC variable power supply without using step down transformer. how con i make it pls help


--
tech

 

[alec_t]

You must use an isolating transformer for safety's sake; either in a linear supply or in a SMPS. The transformer in a SMPS is relatively small because it operates at much higher frequency than the mains.

 

[crutschow]

What do you want this for?
How much current?

 

[kubeek]

Converting AC to AC without a transformer is quite complicated and if you don´t have the experience it really is not worth doing.

 

[throbscottle]

If the current draw is not too much, you could try to get a big old rheostat like they used to use for theatre lights. Expect a lot of heat though, and it's also far from safe. Variac is much better although it is a type of transformer. Why don't you want to use a transformer, and what do you want the power supply for?

 

[tech2000my]

Thanx all of you for your kind support,

I want to operate small solenoid (500mA) operating voltage is 110v - 180v. Our general electricity supply - 230v

Please send small simple circuit for 230AC to 110AC - 180AC variable power supply without using step down transformer

--
tech

 

[alec_t]

small simple circuit for 230AC to 110AC - 180AC variable power supply without using step down transformer

(1) I don't think such a thing exists.
(2) Why do you want it variable just to operate a solenoid?
(3) Why not a transformer?

 

[kubeek]

110V at 0.5A equals to 55W. That is NOT a small solenoid.

 

[throbscottle]

tech2000my, I think you may have misinterpreted the rated voltage for the solenoid - 110 to 180 volts looks like minimum and maximum voltages to operate, rather than a range over which the voltage must be varied. If that is so, any voltage in that range should work.

Correct me if I'm wrong folks, but I'm thinking, if the need to vary the voltage is actually bogus, won't a single series rectifier in the live wire do the job? Just means the waveform won't be sinusoidal, but a small snubber capacitor would take the corners off at least, and to operate a solenoid that shouldn't matter.

 

[alec_t]

won't a single series rectifier in the live wire do the job?

Probably not. If the solenoid current is limited to 500mA primarily by the coil's inductance rather than by its resistance then rectifying the AC voltage will increase the rms current and may well lead to overheating of the solenoid.

 

[ChrisP58]

If you don't mind wasting the heat, you could use a big power resistor equal to the solenoid resistance. Otherwise, a 25VA autotransformer should work.

 

[tcmtech]

I think the OP needs to supply far more information.

I have a 'solenoid' that draws about 500 ma at 230 VAC. Its better known as a 800 amp 1200 volt three phase industrial contractor and it takes up about 1 cubic foot of space!!

(Junk yard find off of a massive three phase air compressor motor control system)