RE: [CAD_CAM_EDM_DRO] L297/L298 board concern

Thanks to all who responded, I'll check it out when I get home but I think
that's the problem.

Gary

> -----Original Message-----
> From: JJ [mailto:jj5412@...]
> Sent: Friday, November 15, 2002 12:50 PM
> To: CAD_CAM_EDM_DRO@yahoogroups.com
> Subject: RE: [CAD_CAM_EDM_DRO] L297/L298 board concern
>
>
> If unconnected, the current to the motor is maxed out, that's your
> problem.
> Figure Vref by calculating the voltage drop across your sense resistor
> at the current you want. Ie. I have 0.5 ohm resistors, and I want 1.5
> amperes, so:
>
> I x R = V
> 1.5 x 0.5 = 0.750
>
> So that's what I set Vref to. I measure from ground to pin 15 on the
> L297, while turning the pot I connected to it.
>
> Regards,
> JJ
>
> Be Kind, Be Careful, Be Yourself
>
>
>
> > -----Original Message-----
> > From: Rose, Gary [mailto:Gary.Rose@...]
> > Sent: Friday, November 15, 2002 9:23 AM
> > To: 'CAD_CAM_EDM_DRO@yahoogroups.com'
> > Subject: RE: [CAD_CAM_EDM_DRO] L297/L298 board concern
> >
> >
> > Yes, I was just looking at the board and there's a connection
> > for Vref and I
> > mistakenly left it unconnected. Just out of curiosity, what
> > should Vref be
> > for what current? If it's unconnected, what would the current be?
> >
> > Thanks again guys!
> >
> > Gary
> >
> >
> > > -----Original Message-----
> > > From: James Cullins [mailto:jcullins@...]
> > > Sent: Friday, November 15, 2002 9:03 AM
> > > To: CAD_CAM_EDM_DRO@yahoogroups.com
> > > Subject: Re: [CAD_CAM_EDM_DRO] L297/L298 board concern
> > >
> > >
> > > I believe it limits the current during run as well.
> > > Jim
> > > ----- Original Message -----
> > > From: "Rose, Gary" <Gary.Rose@...>
> > > To: <CAD_CAM_EDM_DRO@yahoogroups.com>
> > > Sent: Friday, November 15, 2002 7:46 AM
> > > Subject: RE: [CAD_CAM_EDM_DRO] L297/L298 board concern
> > >
> > >
> > > > Thanks for the good information on the Vref, I'm definitely
> > > going to look
> > > > into it.
> > > >
> > > > I'm not sure if that's my problem though. I was running
> > > the motor on the
> > > > bench using a clock generator and a power supply. The
> > > motor was turning
> > > > continuously, so I don't think the Vref circuit that lowers
> > > the current
> > > > after 100ms would even kick in there.
> > > >
> > > > I'm going to try lowering it anyway and see what I get,
> > > anybody got any
> > > > other suggestions?
> > > >
> > > > Thanks
> > > >
> > > > Gary
> > > >
> > > >
> > > > > -----Original Message-----
> > > > > From: JJ [mailto:jj5412@...]
> > > > > Sent: Friday, November 15, 2002 7:41 AM
> > > > > To: CAD_CAM_EDM_DRO@yahoogroups.com
> > > > > Subject: RE: [CAD_CAM_EDM_DRO] L297/L298 board concern
> > > > >
> > > > >
> > > > > I think the suggestion that the Vref is to high is
> > > probably correct. I
> > > > > checked my L298s yesterday after a 4 hour run, and they were
> > > > > cool, close
> > > > > to ambient. I have multiwatt-15 heatsinks clipped on
> > with thermal
> > > > > grease, and they're in an enclosure with a 100cfm fan
> > > blowing directly
> > > > > on them.
> > > > >
> > > > > Regards,
> > > > > JJ
> > > > >
> > > > > Be Kind, Be Careful, Be Yourself
> > > > >
> > > > >
> > > > >
> > > > > > -----Original Message-----
> > > > > > From: B Snowden [mailto:bsnowde@...]
> > > > > > Sent: Friday, November 15, 2002 12:46 AM
> > > > > > To: CAD_CAM_EDM_DRO@yahoogroups.com
> > > > > > Subject: Re: [CAD_CAM_EDM_DRO] L297/L298 board concern
> > > > > >
> > > > > >
> > > > > > Gary,
> > > > > >
> > > > > > I let the smoke out of one of my L298 also awhile
> back. Mine
> > > > > > had a heat sink on it. What I have now done, cut angle
> > > > > > aluminum to 6.75 in long. I have three L298's in a row. I
> > > > > > connected the aluminum
> > > > > > to the heat sinks of all three L298's. So what I
> end up with
> > > > > > is a heat sink attached to the heat sink of the
> three L298's.
> > > > > > When I get the board installed into a case, I
> plan to use
> > > > > > a fan to draw
> > > > > > air over the L298's. By adding the extra heat sink, I
> > > > > > dropped the temp from about 230+ F to around 160 - 205 F. I
> > > > > > do not know what the temp was when one of them smoked. The
> > > > > > fan should cool it even
> > > > > > more. I think you can get by without the extra heat sink,
> > > > > > but it would need to be installed in a case where a
> fan would
> > > > > > draw air over the L298's in a proper way. The extra heat
> > > > > > sink allows me to run
> > > > > > outside a case, and when I do install it, it should allow me
> > > > > > more margin, provided I have proper air flow.
> > > > > >
> > > > > > Bruce
> > > > > >
> > > > > >
> > > > > >
> > > > > > stirlinguy wrote:
> > > > > >
> > > > > > > Guys,
> > > > > > >
> > > > > > > I have a L297/L298 board that seems to be getting
> > > REAL hot. It's
> > > > > > > basically just the circuit from the L297 datasheet. A
> > > > > > friend of mine
> > > > > > > had the board made up with another order. I built it
> > > a few months
> > > > > > > ago, got a motor spinning (I think I was only using about
> > > > > 12v supply
> > > > > > > then), then put in on the shelf. I was playing
> > with it today.
> > > > > > >
> > > > > > > When I run it, the L298 gets really hot. In fact, I
> > > didn't have a
> > > > > > > heatsink on it and the smoke got let out. After
> > > > > replacing the L298
> > > > > > > (and adding a heatsink), it seems to work OK, but
> > > still gets very
> > > > > > > hot. I don't want to run it too much for fear more smoke
> > > > > > may ruin my
> > > > > > > day.
> > > > > > >
> > > > > > > I am using a 24V power supply, the motor is a size 23
> > > > > that is rated
> > > > > > > for 3A, but should work fine with 2. It is stone cold
> > > > > when running
> > > > > > > at low speed from the driver. The L298 on the other hand
> > > > > could cook
> > > > > > > dinner.
> > > > > > >
> > > > > > > Anybody else have this problem? I'm not sure if
> > > there's something
> > > > > > > else screwy with the board, but the amount of heat I'm
> > > > > getting makes
> > > > > > > me wonder.
> > > > > > >
> > > > > > > Thanks in advance
> > > > > > >
> > > > > > > Gary
> > > > > > >
> > > > > > > Addresses:
> > > > > > > FAQ: http://www.ktmarketing.com/faq.html
> > > > > > > FILES:
> http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/
> > > > > > > Post Messages: CAD_CAM_EDM_DRO@yahoogroups.com
> > > > > > >
> > > > > > > Subscribe: CAD_CAM_EDM_DRO-subscribe@yahoogroups.com
> > > > > > > Unsubscribe: CAD_CAM_EDM_DRO-unsubscribe@yahoogroups.com
> > > > > > > List owner: CAD_CAM_EDM_DRO-owner@yahoogroups.com,
> > > > > > wanliker@...
> > > > > > > Moderator: jmelson@... timg@...
> > > > > > [Moderator]
> > > > > > > URL to this group:
> > > http://groups.yahoo.com/group/CAD_CAM_EDM_DRO
> > > > > > >
> > > > > > > OFF Topic POSTS: General Machining
> > > > > > > If you wish to post on unlimited OT subjects goto:
> > > > > > aol://5863:126/rec.crafts.metalworking or go thru Google.com
> > > > > > to reach it if you have trouble.
> > > > > > > http://www.metalworking.com/news_servers.html
> > > > > > >
> > > > > > > http://groups.yahoo.com/group/jobshophomeshop I consider
> > > > > > this to be a sister site to the CCED group, as many of the
> > > > > > same members are there, for OT subjects, that are
> not allowed
> > > > > > on the CCED list.
> > > > > > >
> > > > > > > NOTICE: ALL POSTINGS TO THIS GROUP BECOME PUBLIC DOMAIN BY
> > > > > > POSTING THEM. DON'T POST IF YOU CAN NOT ACCEPT THIS.....NO
> > > > > > EXCEPTIONS........
> > > > > > > bill
> > > > > > > List Mom
> > > > > > > List Owner
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > > Your use of Yahoo! Groups is subject to
> > > > > > http://docs.yahoo.com/info/terms/
> > > > > >
> > > > > >
> > > > > > Addresses:
> > > > > > FAQ:
> > > > > > http://www.ktmarketing.com/faq.html
> > > > > > FILES: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/
> > > > > > Post Messages: CAD_CAM_EDM_DRO@yahoogroups.com
> > > > > >
> > > > > > Subscribe: CAD_CAM_EDM_DRO-subscribe@yahoogroups.com
> > > > > > Unsubscribe: CAD_CAM_EDM_DRO-unsubscribe@yahoogroups.com
> > > > > > List owner: CAD_CAM_EDM_DRO-owner@yahoogroups.com,
> > > > > wanliker@...
> > > > > > Moderator: jmelson@... timg@...
> > > > > > [Moderator]
> > > > > > URL to this group:
> > http://groups.yahoo.com/group/CAD_CAM_EDM_DRO
> > > > > >
> > > > > > OFF Topic POSTS: General Machining
> > > > > > If you wish to post on unlimited OT subjects goto:
> > > > > > aol://5863:126/rec.crafts.metalworking or go thru Google.com
> > > > > > to reach it if you have trouble.
> > > > > > http://www.metalworking.com/news_servers.html
> > > > > >
> > > > > http://groups.yahoo.com/group/jobshophomeshop I consider
> > > > > this to be a
> > > > > sister site to the CCED group, as many of the same
> > > members are there,
> > > > > for OT subjects, that are not allowed on the CCED list.
> > > > >
> > > > > NOTICE: ALL POSTINGS TO THIS GROUP BECOME PUBLIC DOMAIN BY
> > > > > POSTING THEM.
> > > > > DON'T POST IF YOU CAN NOT ACCEPT THIS.....NO
> EXCEPTIONS........
> > > > > bill
> > > > > List Mom
> > > > > List Owner
> > > > >
> > > > >
> > > > >
> > > > > Your use of Yahoo! Groups is subject to
> > > > > http://docs.yahoo.com/info/terms/
> > > > >
> > > > >
> > > > >
> > > > > Addresses:
> > > > > FAQ: http://www.ktmarketing.com/faq.html
> > > > > FILES: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/
> > > > > Post Messages: CAD_CAM_EDM_DRO@yahoogroups.com
> > > > >
> > > > > Subscribe: CAD_CAM_EDM_DRO-subscribe@yahoogroups.com
> > > > > Unsubscribe: CAD_CAM_EDM_DRO-unsubscribe@yahoogroups.com
> > > > > List owner: CAD_CAM_EDM_DRO-owner@yahoogroups.com,
> > > wanliker@...
> > > > > Moderator: jmelson@... timg@...
> > > > > [Moderator]
> > > > > URL to this group:
> http://groups.yahoo.com/group/CAD_CAM_EDM_DRO
> > > > >
> > > > > OFF Topic POSTS: General Machining
> > > > > If you wish to post on unlimited OT subjects goto:
> > > > > aol://5863:126/rec.crafts.metalworking or go thru Google.com
> > > > > to reach it if you have trouble.
> > > > > http://www.metalworking.com/news_servers.html
> > > > >
> > > > > http://groups.yahoo.com/group/jobshophomeshop I consider
> > > > > this to be a sister site to the CCED group, as many of the
> > > > > same members are there, for OT subjects, that are not allowed
> > > > > on the CCED list.
> > > > >
> > > > > NOTICE: ALL POSTINGS TO THIS GROUP BECOME PUBLIC DOMAIN BY
> > > > > POSTING THEM. DON'T POST IF YOU CAN NOT ACCEPT THIS.....NO
> > > > > EXCEPTIONS........
> > > > > bill
> > > > > List Mom
> > > > > List Owner
> > > > >
> > > > >
> > > > >
> > > > > Your use of Yahoo! Groups is subject to
> > > > > http://docs.yahoo.com/info/terms/
> > > > >
> > > > >
> > > >
> > > > Addresses:
> > > > FAQ: http://www.ktmarketing.com/faq.html
> > > > FILES: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/
> > > > Post Messages: CAD_CAM_EDM_DRO@yahoogroups.com
> > > >
> > > > Subscribe: CAD_CAM_EDM_DRO-subscribe@yahoogroups.com
> > > > Unsubscribe: CAD_CAM_EDM_DRO-unsubscribe@yahoogroups.com
> > > > List owner: CAD_CAM_EDM_DRO-owner@yahoogroups.com,
> > > wanliker@...
> > > > Moderator: jmelson@... timg@...
> > > [Moderator]
> > > > URL to this group: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO
> > > >
> > > > OFF Topic POSTS: General Machining
> > > > If you wish to post on unlimited OT subjects goto:
> > > aol://5863:126/rec.crafts.metalworking or go thru Google.com
> > > to reach it if
> > > you have trouble.
> > > > http://www.metalworking.com/news_servers.html
> > > >
> > > > http://groups.yahoo.com/group/jobshophomeshop I consider
> > > this to be a
> > > sister site to the CCED group, as many of the same members
> > > are there, for OT
> > > subjects, that are not allowed on the CCED list.
> > > >
> > > > NOTICE: ALL POSTINGS TO THIS GROUP BECOME PUBLIC DOMAIN BY
> > > POSTING THEM.
> > > DON'T POST IF YOU CAN NOT ACCEPT THIS.....NO EXCEPTIONS........
> > > > bill
> > > > List Mom
> > > > List Owner
> > > >
> > > >
> > > >
> > > > Your use of Yahoo! Groups is subject to
> > > http://docs.yahoo.com/info/terms/
> > > >
> > > >
> > > >
> > >
> > >
> > >
> > > Addresses:
> > > FAQ: http://www.ktmarketing.com/faq.html
> > > FILES: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/
> > > Post Messages: CAD_CAM_EDM_DRO@yahoogroups.com
> > >
> > > Subscribe: CAD_CAM_EDM_DRO-subscribe@yahoogroups.com
> > > Unsubscribe: CAD_CAM_EDM_DRO-unsubscribe@yahoogroups.com
> > > List owner: CAD_CAM_EDM_DRO-owner@yahoogroups.com,
> > wanliker@...
> > > Moderator: jmelson@... timg@...
> > > [Moderator]
> > > URL to this group: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO
> > >
> > > OFF Topic POSTS: General Machining
> > > If you wish to post on unlimited OT subjects goto:
> > > aol://5863:126/rec.crafts.metalworking or go thru Google.com
> > > to reach it if you have trouble.
> > > http://www.metalworking.com/news_servers.html
> > >
> > > http://groups.yahoo.com/group/jobshophomeshop I consider
> > > this to be a sister site to the CCED group, as many of the
> > > same members are there, for OT subjects, that are not allowed
> > > on the CCED list.
> > >
> > > NOTICE: ALL POSTINGS TO THIS GROUP BECOME PUBLIC DOMAIN BY
> > > POSTING THEM. DON'T POST IF YOU CAN NOT ACCEPT THIS.....NO
> > > EXCEPTIONS........
> > > bill
> > > List Mom
> > > List Owner
> > >
> > >
> > >
> > > Your use of Yahoo! Groups is subject to
> > > http://docs.yahoo.com/info/terms/
> > >
> > >
> >
> > Addresses:
> > FAQ: http://www.ktmarketing.com/faq.html
> > FILES: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/
> > Post Messages: CAD_CAM_EDM_DRO@yahoogroups.com
> >
> > Subscribe: CAD_CAM_EDM_DRO-subscribe@yahoogroups.com
> > Unsubscribe: CAD_CAM_EDM_DRO-unsubscribe@yahoogroups.com
> > List owner: CAD_CAM_EDM_DRO-owner@yahoogroups.com,
> wanliker@...
> > Moderator: jmelson@... timg@...
> > [Moderator]
> > URL to this group: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO
> >
> > OFF Topic POSTS: General Machining
> > If you wish to post on unlimited OT subjects goto:
> > aol://5863:126/rec.crafts.metalworking or go thru Google.com
> > to reach it if you have trouble.
> > http://www.metalworking.com/news_servers.html
> >
> http://groups.yahoo.com/group/jobshophomeshop I consider
> this to be a
> sister site to the CCED group, as many of the same members are there,
> for OT subjects, that are not allowed on the CCED list.
>
> NOTICE: ALL POSTINGS TO THIS GROUP BECOME PUBLIC DOMAIN BY
> POSTING THEM.
> DON'T POST IF YOU CAN NOT ACCEPT THIS.....NO EXCEPTIONS........
> bill
> List Mom
> List Owner
>
>
>
> Your use of Yahoo! Groups is subject to
> http://docs.yahoo.com/info/terms/
>
>
>
> Addresses:
> FAQ: http://www.ktmarketing.com/faq.html
> FILES: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/
> Post Messages: CAD_CAM_EDM_DRO@yahoogroups.com
>
> Subscribe: CAD_CAM_EDM_DRO-subscribe@yahoogroups.com
> Unsubscribe: CAD_CAM_EDM_DRO-unsubscribe@yahoogroups.com
> List owner: CAD_CAM_EDM_DRO-owner@yahoogroups.com, wanliker@...
> Moderator: jmelson@... timg@...
> [Moderator]
> URL to this group: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO
>
> OFF Topic POSTS: General Machining
> If you wish to post on unlimited OT subjects goto:
> aol://5863:126/rec.crafts.metalworking or go thru Google.com
> to reach it if you have trouble.
> http://www.metalworking.com/news_servers.html
>
> http://groups.yahoo.com/group/jobshophomeshop I consider
> this to be a sister site to the CCED group, as many of the
> same members are there, for OT subjects, that are not allowed
> on the CCED list.
>
> NOTICE: ALL POSTINGS TO THIS GROUP BECOME PUBLIC DOMAIN BY
> POSTING THEM. DON'T POST IF YOU CAN NOT ACCEPT THIS.....NO
> EXCEPTIONS........
> bill
> List Mom
> List Owner
>
>
>
> Your use of Yahoo! Groups is subject to
> http://docs.yahoo.com/info/terms/
>
>