Resetting Target - Linear Actuator Circuit

Discussion in 'The Projects Forum' started by exd3686, Jul 19, 2012.

  1. exd3686

    Thread Starter New Member

    Jul 17, 2012
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    I’m a complete newbie to circuit design but I’ve done my share of soldering and electronic kits and projects. I’ve done a bit of searching and found some circuits that may work for my application. From other posts I’ve read, I’ll need a two switch latching reverse polarity circuit. Here is what I’m looking to do.
    I’d like to use a 12V linear actuator (http://progressiveautomations.com/l...oke-size-force-200-lbs-speed-094sec-p-36.html) to reset a hinged steel target when it is hit and falls. The actuator has two wires, using reverse polarity to change the direction, and built in limit switches.
    The idea is that the hinged steel target falls backwards and hits the N.O. momentary switch 1 which causes the linear actuator connected to the reset arm to extend pushing the steel target back up to the vertical position. The extended limit switch will make the actuator stop at the extended length and the reset arm hits the N.O. momentary switch 2. The polarity is switched and linear actuator retracts causing the reset arm to drop into the down position out of the way so the target can fall again. Once the actuator is completely retracted the retracted limit switch will stop the actuator. Now the target is ready to be dropped again which repeats the process.
    Here are some crude side-view drawings with the reset arm in the up and down position in case my description is not clear.
    I’d appreciate any help with a circuit that can accomplish this task. I’m looking to uses simple parts such as relays, switches, diodes, etc…. Thank You.
     
    Last edited by a moderator: Jul 19, 2012
  2. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    I found this post moderated (rendered invisible).
    (possibly the link was the cause of the moderation).
    I made it visible and reduced the fontsize, as large fonts are like shouting.
    Now others can see it and give replies.

    Bertus
     
  3. exd3686

    Thread Starter New Member

    Jul 17, 2012
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    Thank you for your assistance!
     
  4. exd3686

    Thread Starter New Member

    Jul 17, 2012
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  5. gerty

    AAC Fanatic!

    Aug 30, 2007
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    I build the steel targets for our range, on our falling plates we use a manual rope reset. What you propose looks like it'll work,BUT, you'll need some pretty tough limit switches. when the targets are hit, the plate slams backwards pretty hard which will hammer your switch.
    The heavier the bullet, the harder it'll slam it. If you make the target heavy (slower moving) than a .22 won't knock it over. Our falling plates are 8" diameter and 1/2" thick. Another thing, what about weather? If you leave it outdoors it'll rust and water might infiltrate the motor. If it's going home when you do, you won't have a problem.
     
  6. exd3686

    Thread Starter New Member

    Jul 17, 2012
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    Gerty,

    This is just a crude conceptual drawing. The switches will be offset with an adjustable "spring finger" to push the switch and it will not take the brute force of a heavy steel target falling.

    This target is intended for long-range high-power rifle and will be shot from 300 to 1200 yards. I appreciate your input. Basically, all I'm looking for is an automated pepper popper that I can set up, shoot, and take home. My major issue is getting the circuit right.

    Thanks,
    exd3686
     
  7. gerty

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    Aug 30, 2007
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    This will work with a few changes. I believe you'll want the actuator to return to the rear position after it stands the target up?
    I'm not at a computer that will allow me to make these changes, if nobody does it by the time I get back on tonight I'll change it. What kind of steel are you going to use for the target? We had some T1 donated once, it was the most durable but too expensive. We use ours for pistols ,and every so often some with a rifle will shoot'em.
     
  8. williamj

    Active Member

    Sep 3, 2009
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    exd3686,

    Read your post this morning and been thinking about it off and all day. Not too sure about how you want it to opperate. Did you want it to...

    Drop and automatically reset up?
    or
    Drop and wait for a manual reset up?

    At 300 to 1200 yards a radio remote manual reset up might be more desirable. If so, remote radio controlled kits (I believe) are available, some even preassembled.

    Will try to work out a simple (as possible) circuit for you.

    williamj
     
  9. strantor

    AAC Fanatic!

    Oct 3, 2010
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    IF the mechanics are designed in such a way that the actuator reaches it's full stroke and stops exactly at the same time as it hits momentary switch #2, then yes, that circuit will work exactly as drawn, minus the stop button.

    However, if it raises the target all the way up and still has 25% of it's stroke left to complete, then no, it won't work. You will have to do something to break the relay latch and then latch the other relay. It could be as simple as using a limit switch with 2 sets of contacts; one normally open and one normally closed. Like this:

    [​IMG]
     
  10. strantor

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    After a few minutes of thought, I realized that I'm wrong. you won't need the portion I drew in red. the circuit will work as is, minus the stop button.

    When you press the "retract" limit switch, it actuates RLY1, which removes the ground from RLY2, so RLY2 will switch off, providing ground for RLY1 to latch and for the motor to turn. So it doesn't matter if the actuator goes to 100% or 75% or anything else.
     
  11. SgtWookie

    Expert

    Jul 17, 2007
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    If you try using a high-power rifle on pepper popper targets, you will wind up with lots of holes punched right through the target.

    Your battery box is also problematic; if a round impacts anywhere on the box, a lead-acid battery will be very short-lived. If the round is still supersonic when passing over the box, the pressure wave will whack the top of the box; that'll also tend to kill a lead-acid battery. You will need to use a slanted front on the box to drive the round down into the dirt in case of impact, and it will need to be a gentle slant to move the round off-course; otherwise a secant round will dig right in and punch through.

    You'll need to keep the limit switches as low as possible to avoid hitting them with rounds. They should be protected from getting dirt/dust/mud in them; you should probably use sealed switches.

    Unfortunately, I'm about out of time for the evening.
     
  12. exd3686

    Thread Starter New Member

    Jul 17, 2012
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    Holy Cr@? guys.....thanks for all the input. The circuit is the major issue for me.....the design may have to change as I get into it.

    To answer a few questions and clear up a few things:

    The target steel is going to be a full sized IDPA target 30H x 18W made out of 3/8 inch AR500 steel. It weighs 55 pounds. I shoot 3/8 inch AR500 steel with 175 grain .308 Sierra MatchKing bullets traveling at 2700 fps all day with only lead splatter left on the target.

    I need to look at the leverage calculations but I'm assuming a 200 lbs. actuator can handle this. It's not a dead lift, just a push up.

    The battery and control box is going to be 8d x 8w x 6h so it will be completely hidden behind the 30H x 18W target in both the up and down position. The switches will also be hidden behind the target as well.

    Right now the idea is shoot the target, it drops, and automatically gets set back up. I've thought version 2 will have two modes...1) drop down and set up 2) press one button for the target to go up to be shot and/or press button two to make the target disappear.

    Thank you so much for all the help and input. I'll be ordering the circuit materials and metal here shortly. May have more questions as I get into it but I'll post some pics along the way.

    Thanks again,
    exd3696
     
  13. gerty

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    Aug 30, 2007
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    I see strantor has a drawing revision for you. I'm going to the range Sunday
    I'll take a few pics of ours, maybe they'll give you some ideas.
     
  14. strantor

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    my revision has been rescinded (see post #9). I say that OP's (Billb's) circuit should work as is, with only modification being to remove the stop switch. What reason makes you say it needs modifications?
     
  15. gerty

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    Once the actuator is extended it needs to hit sw 2 and retract .

    I believe it'll need a double pole switch (as you have drawn) to both stop it and reverse it. How is it going to "remove ground" without that switch.
    Or am I just blind..:eek:
     
  16. strantor

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    DOH! yeah I had it right the first time. :( Talked myself out of it. shoot.
     
  17. exd3686

    Thread Starter New Member

    Jul 17, 2012
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    Now I'm confused....once again I'm a total novice so please explain or tell me to sit back and let the pros handle this.

    My thought was, in theory, that once the actuator is fully extended the actuators internal limit switch would be hit causing the actuator to stop extending and make the circuit reverse it's polarity. At the same time, switch two would be hit by the reset arm causing the actuator to retract until the internal limit switch stops the actuator in the complete retracted position.

    My brain hurts!
     
  18. strantor

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    right, that's the basics of it, but there's 2 relays in the circuit which makes it a little more complicated (no, I don't think there's a way to make it simpler).

    The way the circuit works (original, as you posted it) is that:
    1. initial conditions: +12V comes in and stops at the 2 switches and at the 2 Normally Open (NO) contacts of RLY1 and RLY2.
    2: you press the "extend" switch:
    2.A: the incoming +12V current flows through RLY2 coil, which switches RLY2 (takes a < fraction of a second). Now RLY2 has switched, and the voltage that *was* waiting at the NO contact is allowed to flow through the Common (COM) terminal of RLY2.
    2.B: Now the current flowing through the COM terminal of RLY2 has 2 paths to take, and it takes both. One path is through the motor, through the COM and Normally Closed (NC) terminals of RLY1 to ground. The other path is up through the diode, over and down through the RLY2 coil again. So now the relay is feeding it's own coil and remain energized even once the "extend" switch is released. This what's called a relay latching circuit. This is what keeps your actuator going; otherwise it would stop as soon the switch was released.
    3. RLY2 is latched and the actuator is extending, heading toward it's limit. it hits the "retract" switch and, just as explained before, RLY1 energizes and latches. Well, now both relays are latched, meaning there is +12V present both sides of the motor, and no path to ground for the motor. It's not going anywhere. This is why you need the double pole switch for retract. The double pole switch does the same thing as the "stop" button in the original circuit. it removes the path to ground for RLY2 so that it will deenergize, and allow a path to ground for the motor, so the motor can retract.

    The limit switches in the actuator really don't have an effect on the latching and unlatching functions of the circuit, which I didn't realize at first. The statement I made about "IF the mechanics are designed in such a way..." was wrong. It doesn't matter if the actuator reaches it's limit, we will still need the double pole switch on "retract" to break the latch of RLY2. In fact, the only actuator internal limit switch that will likely be used is the retracted side.

    I've made a couple of erroneous statements in this thread and I apologize if I've added to your confusion.
     
  19. exd3686

    Thread Starter New Member

    Jul 17, 2012
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    Strantor, Gery, SgtWookiwe....thank you all for your help and input. Once the parts come in I'll breadboard the circuit and test it out.

    I was thinking last night in my confusion. My main goal is to have the reset arm push up the target when it falls and then immediately retract so it is out of the way so the target can be knocked down again.

    Can this circuit be made with just the N.O. momentary switch which gets triggered by the falling target.? When the switch is hit the actuator extends and retracts without the use of the second N.O momentary switch? Just a thought.

    exd3686
     
  20. strantor

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    You could eliminate the second switch and put it on a timer, but now you're going into more complicated stuff, not less complicated.
     
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