--===============2135350663== Content-Type: text/plain; format=flowed; charset="gb2312"; reply-type=original Content-Transfer-Encoding: quoted-printable X-MIME-Autoconverted: from 8bit to quoted-printable by pch.mit.edu id m2PN9TQ1014702 Were you able to open the schematic? ----- Original Message -----=20 From: "gardenyu" To: "Microcontroller discussion list - Public." Sent: Tuesday, March 25, 2008 4:48 PM Subject: RE: [EE] question on a motor noise problem 2: motor > > > > Yes, I would say this is really a problem that goes with money issue.=20 > Please forgive me, I'm just an entry level person and my boss will=20 > certainly not pay me any bonus for fixing the problem caused by previou= s=20 > designers. > Thank you both for writing these mails. I appreciate it very much, sorr= y=20 > it's just spiritually. > > > >> From: cc@nope9.com> Subject: Re: [EE] question on a motor noise proble= m=20 >> 2: motor> Date: Tue, 25 Mar 2008 12:41:28 -0600> To: piclist@mit.edu> = >=20 >> It appears you are asking someone to fix your circuit without any >=20 >> compensation. Perhaps you should offer someone on this list some $$$ >= to=20 >> walk you through the whole process.> cc> > > On Mar 25, 2008, at 10:34= =20 >> AM, gardenyu wrote:> > Hi:> > > This sounds interesting to me. Could=20 >> please show a little drawing > of how the zener and diodes are put acr= oss=20 >> the relay? Thank you very > much.> > This application is for DC=20 >> motor,actually the problem never > happened on a small motor, but the=20 >> controller is just bad on a big one.> > > > > From:=20 >> rgrazia1@rochester.rr.com> To: piclist@mit.edu> Subject: Re: > > [EE]=20 >> question on a motor noise problem 2: motor> Date: Tue, 25 Mar > > 2008= =20 >> 00:26:30 -0400> > I'm sorry I have not followed this thread so > > I m= ay=20 >> be talking out of turn > here. But what is the picking > > voltage of = the=20 >> relay? Can you > try tacking a > zener across the coil > > of the relay? Or a zener and= a=20 > fast switching free > wheeling > > diode? If the transient is very fast= ,=20 > the zener will not work > but > > if it is slow enough it might work. T= he=20 > reversed diodes with the > > zener > in parallel might work. Varistors = can=20 > sometimes shunt motor > > noise, but > they must be carefully selected.= Is=20 > it a DC motor? Is > > it a servo or > stepper? If it is a DC motor I am= =20 > not sure that a > > varistor is a good > choice. I have only used them = on=20 > AC motors. > > But someone else on the list > would know. I have had go= od=20 > success > > with diodes to shunt transients and > back emf. I would be = > >=20 > interested to know how you solve the problem.> > > ----- Original Mess>= =20 > age ----- > From: "Cedric Chang" > To: > "Microcontroller= =20 > discussion list - Public." > Sent: > Monday, March 24,= =20 > 2008 11:42 PM> Subject: Re: [EE] question on a > motor noise problem 2:= =20 > motor> > > > >> >> On Mar 24, 2008, > at 5:56 > PM, gardenyu wrote:> >>> >> Thanks a lot for your kind reply= .>=20 > >>> >> > I would look at D2 tomorrow, if this is really an issue, do y= ou>=20 > >> > have any suggestion on cutting this surge off? RV2 is supposed to= > >>=20 > > be a surge protector, maybe it's not strong enough.> >>> >> It's som= e >=20 > new version that I have, for some reason the designer> >> didn't like >= =20 > the snubber,> >>> >> the relay is certainly a problem, I noticed > befo= re=20 > that when it's> >> turned off and not yet turned on, the > voltage can=20 > rise quite high> >> that causes the relay to click back > and forth for= =20 > times. Do you> >> have any suggestion on related > problem? Thank you s= o=20 > much.> >>> >>> >>> From: cc@nope9.com> Subject: > Re: [EE] question on = a=20 > motor noise> >>> problem 2: motor>> Date: Mon, 24 Mar 2008 15:49:53 -06= 00>=20 > To:> >>> piclist@mit.edu> > > I would resume that circuitry not shown (= =20 > some> >>> form of logic ) > gets > a surge of voltage applied to it and= =20 > that> >>> it enters some > unexpected > > state. My recommendation is to measure> >>> the voltage > at pin 2 of= =20 > > D2. > If you are getting drive voltage at> >>> pin 2 > after the "sto= p"=20 > > is pushed, > then your logic is getting> >>> > hammered by a voltage=20 > > spike.> > Are Q4 and Q? ( the Q below Q4 )> >>> > acting as an active= =20 > > motor brake ? > The circuitry shown does not> >>> > seem to offer any= =20 > > snubbing of the > voltage spike you would get> >>> > from the motor. = The=20 > > relay is going to > allow the motor to be> >>> > disconnected for=20 > > several milliseconds, > certainly long enough to> > >>> allow voltage= =20 > > spiking to occur. I am > assuming the relay is a> > >>> "break before= =20 > > make" variety, otherwise I > don't see how the > relay> >>> contacts=20 > > would survive.> > This design seems a bit strange > to me.> >>> I awa= it=20 > > the commen> >> ts of o> ther > PLs. The fact that R25 is missing rend= ers=20 > > C20 as> >> > useless.> > cc> -- > http://www.piclist.com PIC/SX FAQ &= =20 > > list> >> > archive> View/change your membership options at> http://> = >>=20 > > > > mailman.mit.edu/mailman/listinfo/piclist> >>> >> > Without seeing the = >=20 > rest of your circuit, i cannot suggest a "best> > solution". I can >=20 > suggest that you put a voltage snubber on the DRIVE> > + line. The >=20 > maximum voltage you apply to the DRIVE+ line dictates> > the voltage >=20 > rating of the parts you use for the voltage snubber. Try> > first >=20 > putting an MOV ( metal oxide varistor ) across DRIVE+ to> > ground. >=20 > Multiply the maximum voltage for DRIVE+ by 1.1 and select an> > MOV > t= hat=20 > has that voltage rating. Without knowing how much current> > > your mot= or=20 > draws and it's inductance, I would say start with an MOV> > > that abso= rbs=20 > about 5 Joules. I also don't know where you buy > parts,> > so I cannot= =20 > suggest a source for the MOV.> >> > cc> > -- > > > http://www.piclist.c= om=20 > PIC/SX FAQ & list archive> > View/c> hange your membership options at> = >=20 > http://mailman.mit.edu/mailman/ > listinfo/piclist > > -- >=20 > http://www.piclist.com PIC/SX FAQ & list > archive> View/change yo > ur membership options at> http:// >=20 > mailman.mit.edu/mailman/listinfo/piclist>=20 > _________________________________________________________________> =D3=C3= =CA=D6=BB=FAMSN=C1=C4=CC=EC=D0=B4=D3=CA=BC=FE=BF=B4=BF=D5=BC=E4=A3=AC=CE=DE= =CF=DE=B9=B5=CD=A8=A3=AC=B7=D6=CF=ED=BE=AB=B2=CA=A3=A1> http://mobile.msn= .com.cn/--> http://www.piclist.com=20 > PIC/SX FAQ & list archive> View/change your membership options at>=20 > http://mailman.mit.edu/mailman/listinfo/piclist> > > -- >=20 > http://www.piclist.com PIC/SX FAQ & list archive> View/change your=20 > membership options at> http://mailman.mit.edu/mailman/listinfo/piclist > _________________________________________________________________ > MSN =D6=D0=CE=C4=CD=F8=A3=AC=D7=EE=D0=C2=CA=B1=C9=D0=C9=FA=BB=EE=D7=CA=D1= =B6=A3=AC=B0=D7=C1=EC=BE=DB=BC=AF=C3=C5=BB=A7=A1=A3 > http://cn.msn.com -------------------------------------------------------------------------= ------- > --=20 > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist >=20 --===============2135350663== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Disposition: inline Content-Transfer-Encoding: 7bit -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist --===============2135350663==--