How can i have 450 Volts ?

[el156]

Hi all

I have a power transfo with 230-0-230 secundary, and i need 450 volts for my next project, now, is there a simple way for me to get 450 volts DC out of this transformer ? I was thinking using a 5R4 tube that i have, and paraleling the plates, so it would be a half wave rect. so, using the 460 v secundary to the plates, would it work to have more or less 450 V on the output ? I need about 300 ma

Thanks

 

[kmtang]

Use a bridge rectifier across the 230-230V winding and follow by C-L-C filtering. The first C should be very small of about 0.5uF. Change the value of the first C to get you the 450V B+.

Johnny

 

[el156]

Use a bridge rectifier across the 230-230V winding and follow by C-L-C filtering. The first C should be very small of about 0.5uF. Change the value of the first C to get you the 450V B+.

Johnny

Thanks Kmtang, i will make a test like that, but what i really would like is a 450 V regulated supply with Mosfets, but that is far more complicated for me...maybe you know a simple schematic to do that ?

Thanks

 

[M Gregg]

Why not take the simple option,

B+ reducer at the bottom of the page..
http://www.geofex.com/Article_Folders/mosfet_folly/mosfetfolly.htm

I guess it depends on how much current you are going to draw..
Heat dissipation in the FET..volt drop etc..

Regards
M. Gregg

 

[tomchr]

Thanks Kmtang, i will make a test like that, but what i really would like is a 450 V regulated supply with Mosfets, but that is far more complicated for me...maybe you know a simple schematic to do that ?

Have a look at my 21st Century Maida Regulator. It was designed for exactly that purpose. You'll find all the design documentation on my website (see link in my signature). I also sell PCBs for this circuit.

~Tom

 

[Tom Bavis]

What's the transformer current rating? A 230-0-230 @300 mA transformer can deliver about 200 mA with a full-wave bridge with cap input, about 300 mA with choke input. Don't even think about half-wave - it's not an efficient use of transformer and other components.

 

[el156]

What's the transformer current rating? A 230-0-230 @300 mA transformer can deliver about 200 mA with a full-wave bridge with cap input, about 300 mA with choke input. Don't even think about half-wave - it's not an efficient use of transformer and other components.

The transformer is 230-0-230 @ 500 Ma ,so is ok for what i need

 

[Elvee]

what i really would like is a 450 V regulated supply with Mosfets, but that is far more complicated for me...maybe you know a simple schematic to do that ?

Depends on your priorities, but if you look for decent performances and excellent resilience and survivability, this type of regulators might be an option.
http://www.diyaudio.com/forums/power-supplies/198986-simple-hv-series-regulators.html
With the right version and suitable components, they can be made to survive indefinite shorts, even with a smallish heatsink.
The general performance level is only that of a first gen maida, but this is sufficient for lots of applications, and unlike maida-type regulators, they can accept any arbitrary level of abuse (depends on your design options and components choices, of course)

 

[Eli Duttman]

If you bridge rectify the end to end 460 VAC and cap. I/P filter, you get (ignoring losses) approx. 650 VDC. Hybrid bridge rectify the 460 VAC with snubbed, series wired, pairs of UF4007s on the "cold" side and a 5R4 on the "hot" side. The forward drop at 250 mA. of a 5R4 is a whopping 67 V. That loss is favorable here, as the Maida regulator will have to dissipate less power.

Energize the 5R4's filament with a CT 5 VAC winding. Take the "raw" B+ from the CT. Insert a CL90 inrush current limiting thermistor between the CT and the PSU filter. Use a 22 μF. cap., at the filter's I/P.

 

[el156]

Thank you very much for the advises here, i will build the circuit and see how it behaves, and maybe order 2 boards for the Maida regulator ,wich seems to be very good for my needs