Re: [CAD_CAM_EDM_DRO] 48V 10A! Mauch 2A board?

Hi Randy,

Nice find! If you find another one, give me a call! I've come across a
source of 28v, 6A transformers; I'm going to run them in parallel, and
maybe even series-parallel. Now to find a bigger cap, I have a 40K, 50v
cap, but would need a higher voltage for for series, and more C for
parallel.

Your supply sounds like too much for the L298's, IMO. You might examine
the primary taps, I assume it's regulated, you could lower the taps, and
pull off voltage directly across the filter cap. That might possibly
lower your voltage to an acceptable value.


Alan KM6VV


Randy Gordon-Gilmore wrote:

>
> I was cleaning up some in the garage/shop (what else do you do with a day
> off work anyway? :-) and ran across a 48V 10A linear supply (an Elpac
> BFS500-48) that I didn't know I had! It was in a piece of equipment thrown
> away at work a while back, that I dumpster-dove.
>
> I've been having random intermittent dropouts (where an axis will stall and
> whine instead of moving) on my Sherline (Mauch 2A board, 24V 8A switching
> supply) and remember reading that switching supplies will sometimes not
> have a tolerance for the spiky voltages produced by a chopper driver. I do
> have a 4700ufd 50V cap across the output terminals of the supply.
>
> So far, my response has been to set G0 moves at 20ipm from 30ipm and lower
> the acceleration to where it audibly ramps. But then, on finish profiling
> moves at 12ipm an axis (usually X) will still sometimes stall. It's
> frustrating, since 99% of the time 30ipm rapid and 12ipm profiling are
> fine.
>
> I'm tempted to wire in the linear supply, but Dan has only mentioned trying
> the board at 38V. I do have a little switching regulator feeding the 5V
> logic input, and have a regulated 5V linear supply that I could also use
> there. Make that would also use, since I just saw that the 78SR105V
> regulator has a 30V maximum input.
>
> Has anyone used a 2A board on 48V? The L298 datasheet says 46V working
> voltage, with 50V absolute maximum. Would I be pushing things too far with
> 48V? Dan, what would be the next component I should beef up? :-) The
> L298's are on a big finned extruded heatsink with a fan blowing down its
> length.
>
> Best regards,
>
> Randy