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How to reduce noise from a DC motor?
I am designing a circuit with a DC motor 12V DC Reversible Gearhead Motors – 70RPM and some other stuff including a MCU and a LASER, all driven from a single 12V source and am concerned about big HF noise ripple from the motor (electrical rather than radiative but no harm in reducing both).
What kind of current does a DC motor have?
Another concern is the current spike and voltage dip that occurs when starting the motor. This motor has a stall current of only 390mA, so provided your 12V supply can handle that you shouldn’t have to worry about it.
How many capacitors are in a DC motor?
Small capacitors (1 or 10nF) connected across the terminals in a variety of combinations including between Vcc/Gnd, two between Vcc/Gnd with the middle connected to the case exterior, and a combination of the above two. Non-polarised if the motor needs to run both ways.
Why do you need capacitors at the motor terminals?
You should always put a capacitor across the motor terminals even if your circuit is not affected, because brush arcing creates rf noise that can interfere with other equipment (eg. AM radios). The usual recommendation is to install two 0.1uF ceramic capacitors, one connected from each motor terminal to the case.
How do we reduce sparking at the brushes of DC motors?
As you interrupt current in an inductive circuit, high inductive spike is generated at the gap of interruption，thus, sparking is generated, the sparking is due to air molecules being ionised by the high voltage. The only way to eliminate sparking is to have no inductance in the winding, which is not possible. 3. The Solution of Solving the Spark 3.
How are capacitors used to reduce the noise?
Regarding your points to reduce the noise: That’s correct, except of the mention of capacitor polarity: anyways the capacitors must be ceramic, designed for working under high frequency, not electrolytic or paper even if motor will work only in one direction.
Why are carbon brushes used in a DC motor or a DC generator?
Carbon is used rather than metal, because it is better to have a soft material rubbing against the commutator. In that way, the easily replaced brushes are worn away rather than the much harder to replace copper alloy commutator. Carbon is a reasonably good conductor.