designing of high voltage power supply

[sush]

hi ,
i'm new to this forum. i want to design a regulated DC power supply having specifications as:


output voltage: 0 - 300 volts DC
current rating: 0 - 500 mA

input voltage: 220 volts AC

I would appreciate any help provided.

 

[IanP]

Here is a link to 0-300/100mA power supply:
http://www.geocities.com/tjacodesign/300vsup/300vsup.html
To increase current to 500mA you will need to change the current limiting power resistor (R2=1.4Ω), and I would add another 2 Mosfets in parallel with T1. Obviously you will need to mount all 3 mosfets on a reasonable size heatsink ..
You may also need to double or tripple the size of the smoothing capacitor ..
And the last thing, which I probably don't need to mantion, is this: be careful, 300V is a very dangerous stuff :!::!::!: ..
Regards,
IanP

 

[sush]

thanks for the great help. but how can i control the current and i think r3 is controlling the voltage.

Added after 6 minutes:

one thing more i wanted to ask you can i control this output voltage using microntroller.cause i have to control some other things also i am working on 89c 51 .

 

[IanP]

As far as the current control is concerned, this configuration allows you to adjust the current limit within certain range. For example, if R2=20Ω (rated for at least 20W) then the minimum current will be ≈35mA. To have the current limit adjustable, you will have to connect in parallel to this 20Ω resistor a 100Ω variable resistor in series with 1.3kΩ resistor. The VR will come at the T1 side, and the base of T2 will be fed from the middle pin of the 100Ω VR.
If you would like to control the output voltage by a microcontroller you will need to use an isolated opamp or an optically isolated linear optocoupler.
This can be done by replacing R3 (voltage control) with a transistor-based differential amplifier driven by that isolated circuit, and will require extensive modifications to the previously suggested circuit ..
Regards,
IanP

 

[mirofloripa]

How to do the high voltage 300vsup power supply posted at http://www.geocities.com/tjacodesign/300vsup/300vsup.html
symmetric (+/- 0-330V)? I am also would like to obtain a high negative voltage.