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| Time to do manure again and as usual I've changed something (motor driving gearbox to linear actuator to run the 6" ball valve). It wasn't working at first and after talking to agleader I decided to pull the raven boost box out of the system (AL says they can handle 15 amps). Right now I have a too big actuator in place that doesn't have limit switches. I think it will get me by until the correct actuator shows up (new one is a little less force, 10A max and has fixed limit switches). In the long run I'd still like to boost the current with another device to give me more 'headroom' and not damage the actuator (I can get a flow error if I run the current actuator too long manually). The boost circuit ends up being a little complicated since it has to switch polarities. The Raven box was quite complex and really not large enough. Anyone have a circuit diagram for a booster/amplifier that can change polarities?
thanks,
Pat
PS: another option would be a couple of relays like this:
http://www.firgelliauto.com/product_info.php?cPath=101&products_id=...
One relay would be for the reversing function - wire one lead from the module to the relay coil and the other side of the coil to ground/negative so when the module lead turns positive it energizes the relay and changes power polarity to the actuator and if the module lead is negative nothing happens. I'd still need a 2nd relay wired before the reversing relay that would be the main on/off switch (it's coil would be energized by the module output which could be reversed polarity or not and it shouldn't matter).
Edited by Pat H 11/6/2011 15:54
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 relay 1.png (26KB - 683 downloads)
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Manitoba, Canada | You can wire up 2 common 30 amp automotive relay's to act as DPDT relay like your schematic above. Does the same thing but the automotive relays are alot more common on the shelf.
Any linear actuators i have got from Firgelli have had internal limit switches, so when i have used 2 relays to reverse polarity all i need is a low current + or - to activation to either retract or extend the actuator all the way. And it dosnt matter if its a constant power because it slides all the way then the internal switch cuts power.
Do you get what im saying? |
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Near Intersection of I-35 & I-90 Southern Mn. | Our guys make a polarity reversing relay box that follows you reasoning for manure situations. Your drawing shows using a DPDT relay for the polarity reversing scheme. This can be done with SPDT relays but the DPDT amounts to the same thing in one relay.
I disagree with one of your statrments about the relay not doing anything but I may not understand you completely. With the drawing that you have the output to the actuator might be +/- with the coil engergized and would be -/+ when the coil is not energized. The leads leading to the motor would always be "hot" but of one polarity or the other. This is why limit switches on the actuator are necessary.
When the Master is in the OFF, position you would want this relay to send a full constant decrease to the actuator so that it closes the ball. It would be the limit switches job to break this connection when the actuator reaches the fully closed position.
The other limit switch on the actuator would break the increase action so that once the actuator is fully open the motor on the actuator would stop. Again a limt switch is needed on each end of the stroke.
Edited by tedbear 11/6/2011 16:14
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| I should have scanned my schematic with the 2 relays - the diagram pic I show is just the mfr's for the reversing function (power to the relay causes it to reverse). To make it so the reversing relay only switches when it needs to, it would be connected to just one of the module's signal lines and the other to ground/-12volts. When the module switches polarity it would either energize the relay or do nothing (if the module lead is at -12v - nothing happens). btw - the relay has NC/NO connections so unenergized is one direction and energized would be the opposite.
Anyway, I just need to get this thing going and hopefully the firgelli actuator will be exactly what I need - I'll still need to make some sort of cover to keep the manure off it. In the mean time I just hope the surplus center actuator draws few amps (and not the 50amp maximum it shows in the specs) and I'll probably run it in manual when I get close to empty to avoid it going to full open and running against the slip clutch.
thanks,
Pat |
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Manitoba, Canada | I agree with everything ted said. You have mentioned several times that your concerned about draw of the actuator. Unless im missing something as long as your using either the dpdt relay like you posted or two spdt relay's your amperage draw of your linear actuator wont really matter as far as your rate controller goes. You are basically creating a low amperage "trigger" with the relay's and the motor current just goes through the relay's to a good battery connection. It wont take much more than a couple milliamps to energize the linear actuators which will be no problem with your rate control system. Just make sure if your going to use the internal limit switches in the actuator that the valve is allowed to fully open and fully close in the stroke.
I have used the rubber boots that go over those firgelli linear actuators and they seal the unit up pretty good, something to consider maybe.
Clear as mud?
Edited by nevinstobbe 11/7/2011 10:03
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Manitoba, Canada | http://www.facebook.com/photo.php?fbid=10150367450203250&set=a.1015...
Not sure if this works for you but i drew up a fancy schematic of how Id wire it, as i said earlier the only reason I use 2 relays is because i always have a few in the toolbox. On your rate controller what is the trigger to close the valve? a positive or a negative? i forgot to ask so thats why i just put both the pos and neg wires to your rate controller, if its only one or the other just put the unused one to battery. The power wires need to go to battery and you will want to keep the smoke inside the wires so put in a fuse, 10a should be fine unless you have a really big actuator.
The grey thing in the center is your linear actuator. If it is working backwards to how you want it to run, just flip the wires.
Edited by nevinstobbe 11/7/2011 10:22
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| Facebook says the link doesn't work. Anyway, right now I don't have any relays and I'm running direct (if it would stop raining) from the liq control module. The actuator I have coming is a 10amp max so maybe I don't need anything between the module and actuator - though it might be the safe play. Also, I don't actually close the valve to shut it off. Generally when the tank empties the flow rate gets wacky and I raise the tool bar (which has a switch to stop acre counting) and disengage the pto.
I think I'll try putting a rubber boot over the actuator - that might work really well.
As far as the schematic/relay wiring I think I need one relay to turn the power on to the actuator and another to change polarity. Whenever the module sends a signal it would turn on the power relay (module wired to relay coil, 12v from battery wired to contacts). From the on/off relay power would go to the reversing relay. It's all kind of relative so I just have to pick one of the module leads to wire to the reverse relay with the other side of the relay coil to -12volts. If it reacts backwards I'll change module leads.
Update: I tried it out and my current actuator takes too much current and it's causing over current errors. I think I'm going to order a couple of the firgelli relays unless you guys know of a better source for a dpdt relay.
thanks,
Pat |
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Manitoba, Canada | This will take care of you without ordering relay's from firgelli. You can get 30 amp spdt relays anywhere
Edited by nevinstobbe 11/7/2011 19:52
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376359_10150367450203250_512268249_8607523_145973320_n.jpg (37KB - 240 downloads)
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| Thanks, that's much easier and will do what I need to do. It looks like we'll have enough rain tonight to slow things down for tomorrow, so I'll try out the relays on my current actuator.
thanks,
Pat |
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Manitoba, Canada | My email is in my profile if you need any clarification |
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Running a linear actuator from the agleader liq module
