PCB transformer from 5 to 350

[dkace]

circuit for double voltage

Hi,
I want to use a transformer from 5V to 350V. I know just a few things about transformers in PCBs. So, can somebody explain the basics around transformers and suggest how can I build or find one to fit my specifications? The output current is small, the transformer drives a UV sensor.
D.

 

[suromenggolo]

german pcb transformer

for small current, use diode circuit for double voltage, it can step up to high voltage.

 

[dkace]

Ok, current is smal, but I don't want double voltage I want 350/5 == 70 times more. The current is 10-30mAs. The question is how can I build a circuit with a transforer to give me this output.
D.

 

[vdaniel]

The best solution is to use CCFL transformer from

**broken link removed**

For a schematic you can search MAXIM or Linear sites. There are schematics for the CCFL backlight lamps. But you do not need to use their chips. Just make a current driven converter, powered trough inductor.
The output voltage is a function of the input voltage. Besides this converter has a sinusoidal output and makes less noise.

Varuzhan

 

[IanP]

Another option is to use a standard low-power transformer (5V/230V) and drive the secondary with a typical 50Hz square wave. On the HV output you will have 230Vac which after rectification should give you something about 336Vdc ..
Small mains transformers are off-the-shelf and not expencive ..

 

[vdaniel]

The best solution is to use CCFL transformer from

**broken link removed**

For a schematic you can search MAXIM or Linear sites. There are schematics for the CCFL backlight lamps. But you do not need to use their chips. Just make a current driven converter, powered trough inductor.
The output voltage is a function of the input voltage. Besides this converter has a sinusoidal output and makes less noise.

Varuzhan

 

[dkace]

Thanks Varuzhan, nice links but still I am lost.
I need a transformer with one secondary to drive a low current UV lamp, not a back light. What I have in mind is to build a transformer of my own, but I don't know the basics. So , still, if someone can give me specific guidence, is more than welcome.
D.

 

[vdaniel]

You can make in the secondary a bridge from fast 1kV or 600V diodes.
I do not recommend you to make a such transformer yourself,
you will get a lot of problems with it.

Varuzhan

 

[dkace]

Ok, you opened new horizons with your link my friend. I found several interesting applications in Linear that I am working on right now.
When I say I want to make it by my own, I mean in the case that such a transformer doesn't exist allready.
The bridge you are suggesting isn't it for rectifing the output? My original thought was to take a 350 to 5 and reverse it, but this would be quite huge wouldn't be?
I am still looking for some initial info on transformers, cores etc to guide me.
D.

 

[haymeron]

Thanks Varuzhan, nice links but still I am lost.
I need a transformer with one secondary to drive a low current UV lamp, not a back light. What I have in mind is to build a transformer of my own, but I don't know the basics. So , still, if someone can give me specific guidence, is more than welcome.
D.

+++++++++++++++++++++++++++++++++++++++++++++++++++

Get from the manufacturer the parameters for the UV lamp.
Use the following circuit to drive the lamp.
**broken link removed**
Attached MathCad file to calculate the circuit including the transformer.

Added after 9 minutes:

Thanks Varuzhan, nice links but still I am lost.
I need a transformer with one secondary to drive a low current UV lamp, not a back light. What I have in mind is to build a transformer of my own, but I don't know the basics. So , still, if someone can give me specific guidence, is more than welcome.
D.

+++++++++++++++++++++++++++++++++++++++++++++++++++

Get from the manufacturer the parameters for the UV lamp.
Use the following circuit to drive the lamp.
h**p://www.st.com/stonline/prodpres/discrete/powebipo/stsa851.htm
Attached MathCad file to calculate the circuit including the transformer.