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Hi David,
I put together a PWM motor control kit & in its
instructions a capacitor & diode
are wired between the positive lead to the motor
& the negative lead from the motor
(the right way round) these reduce motor hash &
voltage spikes significantly.
I won't give you the values as this motor controller is only rated for 20 AMPS.
I don't know if this is done with Minnkota motors &
controllers. Maybe someone will know.
but I have heard people on site
complaining about motor hash from these units interfering with
other sensitive equipment.
Alan
----- Original Message -----
Sent: Wednesday, May 12, 2010 12:20
PM
Subject: [PSUBS-MAILIST] sonar self
generated noise
To all:
Jens Laland found
this information during research and I felt with past discussion about
motor controllers and other devices causing sonar issues, this should be
shared with the group.
"One of the common errors
incurred with the use of hydrophones is to use a power source that is powering
other (noisy) equipment. For example, the inverter on some boats may produce
noise because of the modified AC waveform it produces. If a battery is being
used to power the hydrophone/preamp combination, one of the worst mistakes
(and easiest to rectify) is the powering of recording devices or other
equipment off of the same battery. This should never be done as the motor
noise from a recorder will be passed through the battery into the hydrophone
and back to you (the battery acts like a capacitor, passing noise back through
the circuit). If you must use the same battery, employ an automotive RF
interference filtering line to your hydrophone's power (e.g. Radio Shack's
#270-051)."
"A good rule of thumb is to always use a
separate battery just for your hydrophones." "With pre-amplified,
battery-operated hydrophones, occasionally electrical noise will also be
introduced due to a difference in potential between seawater ground and the
hydrophone preamp's ground (this type of noise sounds like a hum). One
solution to this dilemma may be to run a wire from your battery's negative
terminal into the seawater."
I have
picked up radio stations without proper shielding in place and interior
lighting when testing indoors as
well!
David
Bartsch for Jens
Laland
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