Gecko 5V supply

Hi Jesse, Brian, Mariss,

I just might have to disagree a little with that statement! Most U.S.
cars have the negative side of power connected to the frame of the car!
The negative side of a PC's power supply is connected to the chassis
ground (probably at one point). On the other hand, the series connected
120 or so lead-acid cells in the battery wells on the submarine I was on
WAS floated from "chassis" ground! The electricians were VERY careful
not to short out one of THOSE cells!

(and on Brian's post)
The PC's 5v power available through the joystick connector PROBABLY has
a fuze (The better boards), just like the keyboard port is supposed to.
As the traces on a PCB are quite thin, I doubt if you'd be able to pull
25A anyway. But a good warning!

NOT that I consider PC power the best choice. Several years ago, I was
rigging up a driver for a stepper motor system (wires strung all over
the office), and had one external open frame power supply driving the
stepper fall into another (where's that cat). When I came in the next
day, flipping on the power gave me a big flash! :>( I fried the driver
module, the CY525 controller, and the parallel port board. The PC
finally came up after I removed the fried parallel board. It limped
along, and really didn't run right after that (it was subsequently
retired).

The lesson: you NEED isolation from the PC! I suggest a 5v wall wart,
and leave the PC's 5v for things like joysticks, mice, hand scanners and
keyboards.

Yes, I'd have to agree with Mariss! Not much electrocution danger from
5v. And I must say, the Gecko's are GREAT DRIVES! I just wired up my
first pair of 201's, and found them to be VERY easy to use! Much easier
then the SD200's I had seen in the past. Although I mounted the pair on
a 6x6x1.5" finned heatsink, they run perfectly cool (37v, 2A)! I did
find out that I'll need a LOT more steps to make them spin FAST! Guess
I'll be going to EMC on a Pentium faster then I thought! (But how does
one get the little covers off? Even after pulling off the terminal
blocks, it only slides back so far. Wouldn't want to bend it!). Again,
I am greatly impressed by these drives! Thank you Mariss!

(An idea)
Did you know, "Surplus" 24v linear power supplies, with "fried"
regulators, are available cheap, and with the regulation stripped out,
can provide about 37v for a stepper driver! Try to find one with a 6A
rating, 4A might get by.

Alan KM6VV


jesse wrote:

>
> On DC power circuits neither side is grounded. So both the + or - buss has zero potential to ground. Years ago when I was running
> diesels generating DC power for electrolytic hydrogen it was normal to feel the bolted buss connections looking for hot spots.
> It took watching someone else doing this a few times before starting to do it. Just don't grab both busses at the same time.
> I would have to do some checking before I did this on electronic systems.
> Jesse
>
> mariss92705@... wrote:
>
> > Hi,
> >
> > Most PCs have a game port. The +5VDC is available on pin of the game
> > port. You cannot electrocute yourself off of 5 volts even if you put
> > the wires in your mouth and stand in a tub of salt water. Haven't
> > tried it myself but I am sure.
> >
> > Mariss