Re: [CAD_CAM_EDM_DRO] Chopper max voltage?

----- Original Message -----
From: "Chris Hellyar" <chris@...>
To: <CAD_CAM_EDM_DRO@egroups.com>
Sent: Thursday, October 05, 2000 11:42 AM
Subject: Re: [CAD_CAM_EDM_DRO] Chopper max voltage?


> Ay, that would sound right, I never actually tried them at the higher
> voltage without the current fall back. The L298 costs $15 NZ a shot here,
> so I wasn't all that prepared to experiment with them when I wasn't going
to
> produce more than five or six of the boards for myself...
>
> re: heatsinks for general info, mine is three bits of 1/16th alloy bolted
> together and spread out like a "fan". They are 2*3 inches (*3) for each
> driver, and there is a 80mm 12V PC fan blowing through the "valleys" on
the
> heatsink, and they still get quite warm to the touch. Where the plates
are
> in contact with each other, and where they press up against the driver
> heatsink tab I've used silicone heat conduction paste. Also the heatsink
is
> mechanically mounted to the PCB with alloys spacers to reduce mechanical
> stress on the driver legs etc.
>
> Had a look at the web site, the new board looks quite tidy, hope it does
> well for you...
>
> Cheers, Chris.
>
> * Design engineer, Assembly worker, Cleaner.
> * Ohmark Electronics. PO Box 5302, Christchurch, New Zealand.
> * http://www.ohmark.co.nz
>
> ----- Original Message -----
> > Without automatic reduced current the l298 doesn't last very long at
36VDC
> > @2A. even with a massive heatsink and fan. I changed the design to use
> > automatic reduced current and they seem to hold up very well. My new
3axis
> > 2A board has this feature. I recommend that beginners stay under 18V
> because
> > of their propensity to use an inadequate heatsink and or fans above
this
> > voltage.
> > Dan
>
>
>
>
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