Re: [CAD_CAM_EDM_DRO] Another Power Supply Question.

> In a message dated 21-Feb-01 18:39:28 Central Standard Time,
> prototype@... writes:
>
>
> > Does the negative pole of the 5V supply in a PC power supply tie to

chassis

> > ground or is the supply truly floating?

The motive for this question came about as I was pondering using the +5V
supply from the PC to pull up the opto inputs on Geckodrives. My current
breakout board (wonderboard) uses a dual output isolated supply on the
board. It requires too much board real estate and parts, running up the
cost.

My current thinking is to put a 4 pin mating connector (floppy drive power
type) and screw terms on the board. If the builder doesn't want to use PC
5V then a wall wart can be connected to the screw terms instead. The second
5V supply will come from a 1W DC/DC isolated converter. This is used to
power the optoisolators between the limit switches and status lines of the
parallel port. It also provides a source for status and indicator LEDs on
the operator console/pendant.

The above modifications to the wonderboard will reduce board size from 35 to
16 square inches. It will also reduce component cost to about half what it
was. The smaller size also allows me to mount the board in a DIN3 rail
bracket.

Doug