Re: low voltage contorl circuit

--- In CAD_CAM_EDM_DRO@yahoogroups.com, Harvey White <madyn@i...>
wrote:

> On Mon, 26 May 2003 18:08:48 -0000, you wrote:
>
> >Hi,
> >
> >has anyone made the low voltage regulator from the

mosfet/transistor

> >design in the files section ?
> >
> >/CIRCUITS/HIGHINPUTVOLTAGEREGULATOR.pdf
> >
> >I need to get 5 VDC from the secondary of a 48V transformer, may

need

> >to use the center tap to get 24VAC for this.
> >
> >just wanted to know how noisy this DC voltage will be.
> >
> >or, if anyone has a circuit to drop higher voltage to 5VDC without
> >adding huge heat sinks to the voltage regulator.
>
> One idea would be to go get either a small regulated 5 volt supply

and

> use it independently, or get a cheap 9 volt dc supply and run it
> through a 5 volt 7805 regulator.
>
> In a CNC setup, this would give you good isolation between the
> voltages and keep the switching noise from the chopper drives

down. I

> plan to do much the same with an isolated board driver (CNC setup)
> being driven from a printer port. I will have a separate power

supply

> for some of the logic circuits, which will be completely isolated.
>
> Harvey
>
>
> >
> >Dave

Hi Harvey,

I am planning on using 5V logic for the EDM and it seems the MOSFETs
for the EDM and the circuit driving them need to have a common
ground. I was hoping to run the 5V off the main power source and
that way keep some of the problems to a minium.

I thought that using a seperate power source does not offer very much
isolation when you need to tie the grounds together.

Dave