power regulator circuit

[shipto]

I am in need of a little help with a circuit to supply power to a 230vdc motor from a mini lathe (just to head of suggestions of using the origional controller its not a option as it blew through many tracks on the pcb due to a stray bit of swarf).
I am no great shakes at electronics but can follow a diagram pretty well and decided to give the circuit pictured below a try.
I have modified it slightly to suit parts I have rather than whats called for (this is mostly just slight changes in resisters and capacitors eg:22k where the 20k is needed) and even though I didnt get time to scope it tonight I think it is working well and the multimeter tells me its giving me 280vdc.
I can see 2 options now:
A) leave this circuit as is and regulate the 280vdc down to the required 230vdc
B) change the components of the circuit to get the required voltage which is what I would prefer to do but am not sure how best to achieve this, I am guessing I would need to replace D7 to give me a different reference voltage?
Any suggestions would be greatly appreciated.

[velocette]

 Hi
Here is a link to an excellent unit for up to 2 hp DC motors

http://www.surpluscenter.com/Electrical/Motor-Speed-Controllers/90-180-VDC-SPEED-CONTROL-W-POT-11-2269.axd

Or browse through

http://www.kbelectronics.com/kb_manuals.html

280 volts dc  on a 230 volts motor is straying into the sparks and smoke release arena

A commercial unit has provision to set speed torque and maximum current and is a much safer option.
The unit in the diagram is absolutely basic no means of tuning it to the motor.

Eric

[John Rudd]

Shipto,
I've sent you a private message.....

[Bluechip]

Shipto

What was that diagram from ?? Judging by the values of C1 - 4 ( ie. 39uF ) I doubt if it was intended to output any more than 200-odd mA ... ( 250VDC @ 200mA is typical for valve kit ??? Amp / Rx ?? )

Velo is right, forget it. It just won't work.

Dave

[shipto]

Its just a diagram I found from google when I put in "hv power regulator".
However it looks like John has a tidier solution so I am going to play with this and see what does what and if i end up blowing one of the transisters it wont be a big deal.
the capacitors I am using are bigger than 39uF and are from single phase motors.
The MJE13005 is able to handle 4 amps continuous 8 amps pulsed according to the spec sheet, which is why I thought this circuit would do my job but I am probably over simplifying things with my limited knowledge of this electronic wizardry.

[John Rudd]

Its just a diagram I found from google when I put in "hv power regulator".
 I am going to play with this and see what does what and if i end up blowing one of the transisters it wont be a big deal with my limited knowledge of this electronic wizardry.

Rather that than injuring yourself....

How did the existing controller die? Swarf in the box?
Is it the board with the mosfet(s) on it?
They can be troublesome....

[shipto]

Rather that than injuring yourself....

not too much worry of that I am playing with this with 3 rcds in place (house, workshop and a plug in one) not to mention a healthy respect of the electricity 

How did the existing controller die? Swarf in the box?
Is it the board with the mosfet(s) on it?
They can be troublesome....

I assume stray swarf was the culprit ( might not have been) the panel was out of the machine but still connected to the plastic board at the time just went pop and upon inspection I saw some of the tracks had blown around the relays.