A 5V DC to 200V DC voltage step up circuit problems

[wf1318]

step up voltage circuit

Hello!

I have looking for a "low DC to high DC" voltage step up circuit long long time.

Fortunately, I found my "Cooler Master Musketeer III" Tube Headphone/Pre amp have this voltage step up design on the circuit board.
And I draw the whole diagram of this circuit.


As you see, a 5V DC step up to around 200V DC via a MC34063 with a few electronics parts and a little transformer.
The kind of transformer is not the general transformer like 220AC to 12AC transformer...

Here is my questions:
1.) What kind of this little transformer called?
2.) How to calculate (may be how to guess) the ratio between 1st & 2nd winding of that transformer?
Because I can't find any value mark on the transformer, only the product number mark on it.
3.) This kind of transformer is really hard to find......so, can I build it by myself? If yes, how to do it?
Or can I modify the general "AC to AC transformer" to do this job?

 

[svhb]

step up circuit

This kind of transformer is typically custom made depending of the application. I'm affraid you will not find it in the store.

The working principle of this circuit is a bit difference than like using a normal line AC (50-60Hertz) transformer. First of all it works on much higher frequency (severla kiloHertz to several 100KHerz), and like used in this schematic, the transformer stores the energy for a part of the switching period, and releases its energy to the secondary (200V side) for the rest of the period. The output voltage can be changed by changing the on-versus off time in a switching period.
A line transformer does not store energy, the power is directlyu transferred from primary to secondary (with some losses of course).

 

[eem2am]

voltage step up circuit

beware boost converter can have RHPZ problem especially with high step up ratios

 

[FvM]

5v to 200v

Some manufacturers have small flyback transformers for of-mains SMPS. They can be used by reversing primary and secondary windings. Generally a winding ratio between 1:10 and 1:40 should work. The 34063 maximum voltage sets an lower limit to the ratio.

 

[umery2k75]

dc step up circuit

Hi wf1318
These kinds of transformers are custom made, you first measure the gauge of the wire and then check the henry for every connection. I hope you can make an alternative to it,if you can't make an alternative, ask a person working on transformer winding, he might help you. They can be bought in simple plastic cases.

 

[max0412]

how to make a dc step up transformer

You can get a cheap ready made flyback transformer here (maybe even a free sample) and do as FVM suggested.

http://www.coilcraft.com/prod_flyback.cfm

Or just buy a Torrid and wrap your own,using magnet wire.I've done this a few times it's pretty tedious you need over a hundred turns on the primary in my case north America. Just beware the dot convention on flyback coupled inductors is inverted.