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Linear Actuator — Parallax Forums

Linear Actuator

JavaJava Posts: 12
edited 2011-10-14 11:19 in BASIC Stamp
Hi. Im very new to working with the basic stamp. I would like to know if i can connect and control a Linear Actuator w/ feedback using the BOE. The actuator is 12v (500ma running, 10A stall). I have a 12v power supply connected to the BOE so i was hoping i could use the unrequlated 12v power directly from the BOE. If that is true do i need some kind of driver? Finnaly, can i program the actuator using Pbasic. Any help would be much appreciated, even if it is just direction to more information. Thanks

Comments

  • ercoerco Posts: 20,256
    edited 2011-10-11 16:21
    Some Firgelli LAs operate just like a servo from their internal feedback mechanism: http://www.firgelli.com/pdf/Servos.pdf

    Others just move to their limits based on applied power polarity, they can be controlled using a DPDT switch or relay: http://www.firgelli.com/pdf/DPDT_Switch.pdf

    What brand are you using?
  • JavaJava Posts: 12
    edited 2011-10-11 16:32
    erco. Thanks. I found the acuator at pololu's website. here is the link http://www.pololu.com/catalog/product/2313. I have not purchased let. This one has position feedback
  • ercoerco Posts: 20,256
    edited 2011-10-11 19:46
    It has a built-in feedback pot of unspecified value. Hopefully it's 5-10K or thereabouts. You can measure the pot with the Stamp's RCTIME command and switch it with a few relays.
  • JavaJava Posts: 12
    edited 2011-10-12 09:15
    Thanks. Since it says it automatically reverses itself once its internal limit switch is activated, do i still need relays to reverse polarity? Do i need a driver that will work with the Stamp. I have a 12v stepper motor that required a driver.
  • ercoerco Posts: 20,256
    edited 2011-10-12 10:54
    It does not auto-reverse after tripping the limit switches, it just disables further motion in that direction by switching in a diode, which only allows you to drive it in the opposite direction.

    So yes, you still need 2 relays. You can either use one SPST (on/off) and one DPDT (reversing) relay, or use two SPDT relays, a little slicker IMHO. You can use the circuit attached with 5V relays, but leave out the red diodes and make a wired connection in their place. Your actuator goes where the motor (M) is.
    bmp
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    Relay H-Bridge.bmp
    234K
  • bsnutbsnut Posts: 521
    edited 2011-10-14 01:35
    Erco circuit will work perfectly for what you are wanting to do. But, what you will need to do is find out what the feedback pot value is. You can either get this actuator that you are talking about to find out what the feedback value is or you find out from the company itself what value is of the feedback pot. Remember, the Basic Stamp can read resistor up to 50Kohm using the RCTIME command.
  • JavaJava Posts: 12
    edited 2011-10-14 11:19
    Much thanks for all the input. I think i will buy the acutator
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