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=20
Thanks a lot for your kind reply.
=20
I would look at D2 tomorrow, if this is really an issue, do you have any =
suggestion on cutting this surge off? RV2 is supposed to be a surge prote=
ctor, maybe it's not strong enough.
=20
It's some new version that I have, for some reason the designer didn't li=
ke the snubber,
=20
the relay is certainly a problem, I noticed before that when it's turned =
off and not yet turned on, the voltage can rise quite high that causes th=
e relay to click back and forth for times. Do you have any suggestion on =
related problem? Thank you so much.


> From: cc@nope9.com> Subject: Re: [EE] question on a motor noise problem=
 2: motor> Date: Mon, 24 Mar 2008 15:49:53 -0600> To: piclist@mit.edu> > =
I would resume that circuitry not shown ( some form of logic ) gets > a s=
urge of voltage applied to it and that it enters some unexpected > state.=
 My recommendation is to measure the voltage at pin 2 of D2. > If you are=
 getting drive voltage at pin 2 after the "stop" is pushed, > then your l=
ogic is getting hammered by a voltage spike.> > Are Q4 and Q? ( the Q bel=
ow Q4 ) acting as an active motor brake ? > The circuitry shown does not =
seem to offer any snubbing of the > voltage spike you would get from the =
motor. The relay is going to > allow the motor to be disconnected for sev=
eral milliseconds, > certainly long enough to allow voltage spiking to oc=
cur. I am > assuming the relay is a "break before make" variety, otherwis=
e I > don't see how the relay contacts would survive.> > This design seem=
s a bit strange to me. I await the commen
 ts of other > PLs. The fact that R25 is missing renders C20 as useless.>=
 > cc> -- > http://www.piclist.com PIC/SX FAQ & list archive> View/change=
 your membership options at> http://mailman.mit.edu/mailman/listinfo/picl=
ist
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