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Sizing a diode — Parallax Forums

Sizing a diode

jdoleckijdolecki Posts: 717
edited 2022-09-29 02:43 in General Discussion

My Scorbot arm has these limit switches with didoes to stop the arm from over travel.

( see drawing)

I building a gripper and would like to do the same for the travel limits.

How do I size the diodes. 24v dc I don’t know the amperage draw but the motor power supply is 2A.

Comments

  • jmgjmg Posts: 14,980

    @jdolecki said:
    How do I size the diodes. 24v dc I don’t know the amperage draw but the motor power supply is 2A.

    What package will suit ? You should check the inrush current for the motor, and size based on that.
    A 3A axial diode as above will work, or you may prefer less voltage drop with a Schottky diode ?

    Axial Schottky diodes come up to 15A, and TO-220 can do up to 45A, and you can get dual diodes in the 3 legged packages.
    The fully encapsulated parts can be easier to mount, like SB2045FCT_T0_00001

  • ercoerco Posts: 20,207

    Most any 2+ amp rectifier diode should work. A few years ago you could have breezed into any Radio Shack and bought a 50-diode assortment for $3, and grab the two biggest barrel diodes in the pack. These days you gotta plan ahead to source them. You should test your motor's actual current draw. For this application I'd say as long as your diodes can handle double the no-load current, you're good.

    As wired, these diodes are only used briefly to reverse away from a limit switch, so I don't think voltage drop is a driving factor.

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