making diy transformer

[muhammad59]

i want to built a step down tr (230v to 12v) by high pressure sodium fixture chock buy combining 2 of them one for primary and one for secondary
note: chock has about (250-300)turn
but how i can connect primary coil to main(230v 50hz)and not happen short circuit ??????

 

[MikeMl]

chock = choke? Choke has a single winding.

To make a transformer, you need two isolated windings on the same iron core. The primary needs to have a few hundred turns of small dia. wire. The secondary needs fewer turns of large dia. wire.

Turns ratio = nS/nP = Vs/Vp = 12/230 = 0.0522, where nS is the number of turns on the secondary, nP is the number of turns on the primary winding.

So nP = nS/0.0522 = 19.2*nS. If the secondary winding has nS=25 turns, the primary nP would require 479 turns.

It is all about fitting the required number of turns on the existing bobbin so that it still fits the core.

 

[muhammad59]

chock = choke? Choke has a single winding.

To make a transformer, you need two isolated windings on the same iron core. The primary needs to have a few hundred turns of small dia. wire. The secondary needs fewer turns of large dia. wire.

Turns ratio = nS/nP = Vs/Vp = 12/230 = 0.0522, where nS is the number of turns on the secondary, nP is the number of turns on the primary winding.

So nP = nS/0.0522 = 19.2*nS. If the secondary winding has nS=25 turns, the primary nP would require 479 turns.

It is all about fitting the required number of turns on the existing bobbin so that it still fits the core.

thank you for good explanation ... in my case i gave main 230v 50hz directely to choke it made short cct ..i just connect primary (250-300)turn
is that happend coz choke has less 479 turns ????

 

[tcmtech]

What did the HID lighting ballast (More correct term for such devices) originally use for a line voltage and how many turns were on the original primary coil set?

Whatever those numbers worked out to be that's the turns per volt value you would want to use for the new windings.

 

[muhammad59]

What did the HID lighting ballast (More correct term for such devices) originally use for a line voltage and how many turns were on the original primary coil set?

Whatever those numbers worked out to be that's the turns per volt value you would want to use for the new windings.

as i mentioned HID lighting ballas has about (250-300)turn for 400w balbs ...it has originaly primary coil only
and light fixture has starter (ignitor )prevent choke from short cct when conduct only for short while using diac thyristor ..but when i use without starter for creating transformer it will be short cct .it seem to be this amount of turns not enough for main 230v 50hz .and also hpsv bulb resistance will decrease to zero after conducting...

 

[tcmtech]

Okay?
This might help you define things in a way that we can better understand being I am getting a strong feeling that English is a second language for you.

**broken link removed**

I suspect that what you have is a ballast similar to the design shown on page 25.

If that is the design you have but for a 400 watt HPS type bulb then yes running the ballast directly off of your 230 volt mains voltage would not work being in the normal working circuit the 400W HPS bulb is producing a 90 - 130 volt drop leaving the ballast coils to only have to work with 100 - 140 volts instead of the full 230 volts.

So if that's what you have you would need to double the present number of coils fo the primary you are designing to work properly on 230 VAC. So basically, you would need to stack two of the ballast coils you have in series to work with your 230 VAC line voltage.

 

[tvtech]

Okay?
This might help you define things in a way that we can better understand being I am getting a strong feeling that English is a second language for you.

**broken link removed**

I suspect that what you have is a ballast similar to the design shown on page 25.

If that is the design you have but for a 400 watt HPS type bulb then yes running the ballast directly off of your 230 volt mains voltage would not work being in the normal working circuit the 400W HPS bulb is producing a 90 - 130 volt drop leaving the ballast coils to only have to work with 100 - 140 volts instead of the full 230 volts.

So if that's what you have you would need to double the present number of coils fo the primary you are designing to work properly on 230 VAC. So basically, you would need to stack two of the ballast coils you have in series to work with your 230 VAC line voltage.

I need a wife with a stack of two huge ballast coils that work in parallel with my primary Nuclear Reactor. Edit...Never mind

 

[large_ghostman]

I need a wife with a stack of two huge ballast coils that work in parallel with my primary Nuclear Reactor. Edit...Never mind

Look up half life TV, you might be disappointing to learn its likely your reactor is running old fuel and not...............what is was. I have the best version which was built about 15 years ago .

.............yeah ok I am shutting up as well..................................

 

[dr pepper]

Tellytech your reactor is a magnox and is now out of date.

As for the lighting ballast I wouldnt take the original windings into account, a better approach would be to use the universal transformer equation and calculate the primary turns based on the material (iron, or it could be silicon steel), frequency, cross sectional area and voltage.

One thing to bear in mind is the contruction of the ballast, I see all the I's and E's are aligned, this is a high magnetic leakage core, meaning saturation and switch on surge could be an issue, maybe not a problem if it is switched on under load and not on for long periods.

This is an interesting vid for transformer design, ok its for torroids, but it gives a non mathematical approach to transformer design.

Wikipedia has a good article, the universal transformer equation is about 1/4 the way down, laminated transformers usually saturate at 1.o Tesla, so that would be your Bpeak.
Adding 30% extra winding turns is a good idea.

https://en.wikipedia.org/wiki/Transformer

Just a semi calculated rough guess I'd say you need around 800 turns primary (based on a core 3x5cm centre), so the secondary would be around 40 turns.
You could join both transformers together, and wind the windings around them both as if they were one, however there would be a lot of leakage unless you bolted or welded them together very tight, so I wouldnt reccomend this, just use the one.

 

[tcmtech]

Unfortunately, that's the problem with using a very low grade and quality single tapped coil type HID lighting chokes. They are not easily adaptable to being rewound and configured for other applications being they don't have a dedicated full line voltage driven primary coil side to them.

Personally, I never knew they made such a choke unit for 400 watt HPS applications. The power factor and line noise from one that size must be horrific, especially on the HV striking start up, by typical modern power system standards.

 

[dr pepper]

They have 30 or so 400w hqi metal halide high bays in the main hall where I work, they have a ignitor unit to strike the tube at 4kv, the units have a power factor correction cap, I'm unaware of any noise issues, that doesnt mean to say they are quiet though.