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Below is an actuator that I am considering. I am not sure on the stroke length that I will need, but that should not play a factor as all of them are 12V DC. They have limit switches that are already built in to them that are non adjustable. That isn't a huge deal, but will make it harder on me to ensure I have the correct stroke length and geometry when mounting. Although, I am sure we could still wire in some limit switches to have it stop before it reaches the internal. For now, let's say I will rely on the the internal limit switches. I still would like to use two Wildgame timers to activate the open and close times.
When you have a free moment could you possibly draw a wire diagram for this? I have a Wildgame timer at home and when I get off work I could take some pictures of it if that would help??
http://www.progressiveautomations.c...stroke-size-force-lbs-speed-118sec-p-228.aspx
When you have a free moment could you possibly draw a wire diagram for this? I have a Wildgame timer at home and when I get off work I could take some pictures of it if that would help??
http://www.progressiveautomations.c...stroke-size-force-lbs-speed-118sec-p-228.aspx
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Hi Bob. Sorry for the slow reply - I just realised that I'm supposed to be doing something on this thread!
Here's the diagram I suggest. It uses two timers. The left one opens the door in the morning; the right one closes it at night.
I have assumed that:
Fully extended actuator = door fully open;
Fully retracted actuator = door fully closed.
The 12V battery is shown at the top left. The symbol at the negative end is a "0V" rail, and all of those symbols in the diagram need to be connected together.
Everything (two timers, two relay coils, and the actuator) are powered from the +12V rail.
The timers must have a relay contact output, which closes (completes the circuit) for a short length of time - long enough for the door to fully open or close, at the appropriate time of day.
These timers drive two relays, K1 and K2, which are needed because (a) multiple contacts are needed for the required switching action, and (b) the extender draws up to 5 amps, so you need good solid relays to drive them.
Each of these relays contains a coil, which is energised by the associated timer, and two sets of "changeover" contacts, with three connections each, called NO (normally open), COM (common) and NC (normally closed).
While the relay coil is not energised, the COM contact touches the NC contact. While the relay coil is energised, it acts as an electromagnet and pulls the COM contact so it touches the NO contact. Therefore, when the coil is energised, the COM contact "changes over" (hence the name) from the NC contact to the NO contact.
Diodes D1 and D2 suppress "back EMF" from the relay coils - a large voltage spike that the coils generate when the current flow is interrupted. Without them, this voltage spike will cause arcing and damage to the relay contacts inside the timers.
The contacts direct the 12V supply from the battery to the actuator. Here's how it works.
In the morning, when you want the door to open, the first timer activates K1. Current flows from the +12V rail into the top COM pin on K1, out the NO pin, and down to the "fully extended" limit switch.
When the door is not fully open yet, this limit switch is closed, i.e. it completes the circuit. So the positive supply is connected to the black wire of the actuator.
I believe (but can't be sure) that positive to black wire makes the actuator extend.
The rest of the circuit is completed by the bottom contact of K1, which connects the actuator's red wire to the 0V rail (back to battery negative).
So the actuator sees 12V DC from the battery, with positive to black and negative to red. As I said, I believe this polarity makes it extend, but the documentation on the PA-14 actuator is very poor and this information is not stated anywhere! (Not even in the limit switch wiring diagram that they supply, which is also very poor quality.)
When the actuator is fully extended and the door is fully open, the "fully extended" limit switch becomes open-circuit and the power to the actuator is cut off.
Diode D3 conducts in the direction of the arrow, so in this situation, current will not flow through it. (This assumes that current flows from positive to negative, aka "conventional current".)
The door close circuit is a similar arrangement using K2. But K2 gets its +12V and 0V feeds from the NC contacts of K1. This ensures that if, for some reason, the timers both activate at the same time, K2 cannot feed current to the actuator while K1 is already driving it in the opposite direction. If that happened, the battery would be shorted out.
So when K1 is not energised, +12V and 0V emerge on the two NC terminals, and feed the COM terminals of K2. When the second timer activates in the evening, K2 activates, and supplies this voltage to the actuator, but with the opposite polarity.
The polarity of the voltage across the two wires in the morning and evening is marked on the diagram, just below K2.
In this case, the actuator receives positive on the red wire and negative on the black wire, which I believe will make it retract.
D3 now conducts, because current is flowing through it in the direction of the arrow. This means that the "fully extended" limit switch has no effect on the supply to the actuator. Since the full actuator current flows through D3 I have recommended a diode rated for 10 amps.
I am assuming that the actuator contains its own limit switch and will stop automatically when it is fully retracted. This is not stated anywhere in the description for the actuator, so you'd better check it!
D4 and D5 are two back-to-back 18 volt, 5 watt zener diodes. These are intended to suppress the "back EMF" that is generated by the motor when the supply to it is turned off. This back EMF could reduce the lifetime of the K1 and K2 contacts by causing arcing. C1 is also for noise and spike suppression.
I hope that's clear enough for you to follow.
There are a few unknowns related to the PA-14 actuator, which is very poorly documented. My main questions are:
1. What polarity is correct for extend, and for retract? I have assumed that red positive, black negative makes it retract, and the opposite makes it extend. This is based on the limit switch wiring diagram on the manufacturer's web site, which is also very short on information, so it could be wrong. If it turns out to be wrong, just swap the wires to the actuator.
2. Does the actuator include a limit switch for the retraction direction? I assume it does, but this is not stated anywhere in the documentation.
Here is a description of the parts needed.
K1,2: relays (socketable, with bases if necessary), with: Coil 12V DC; Contacts DPDT (double pole, double throw) (also called DPCO, double pole changeover), rated for 10A at 24V DC.
D1,2: 1N4007 http://www.digikey.com/product-detail/en/1N4007/1N4007FSCT-ND/965481 USD 0.18 x2
D3: 10A02T http://www.digikey.com/product-detail/en/10A02-T/10A02-TDICT-ND/2242770 USD 0.70
D4,5: 1N5355B http://www.digikey.com/product-detail/en/1N5355BG/1N5355BGOS-ND/1474101 USD 0.53 x2
C1: 4.7 µF 63V film capacitor http://www.digikey.com/product-detail/en/R82CC4470AA30J/399-6028-ND/2704682 USD 2.30
Any questions, ask away
Here's the diagram I suggest. It uses two timers. The left one opens the door in the morning; the right one closes it at night.
I have assumed that:
Fully extended actuator = door fully open;
Fully retracted actuator = door fully closed.
The 12V battery is shown at the top left. The symbol at the negative end is a "0V" rail, and all of those symbols in the diagram need to be connected together.
Everything (two timers, two relay coils, and the actuator) are powered from the +12V rail.
The timers must have a relay contact output, which closes (completes the circuit) for a short length of time - long enough for the door to fully open or close, at the appropriate time of day.
These timers drive two relays, K1 and K2, which are needed because (a) multiple contacts are needed for the required switching action, and (b) the extender draws up to 5 amps, so you need good solid relays to drive them.
Each of these relays contains a coil, which is energised by the associated timer, and two sets of "changeover" contacts, with three connections each, called NO (normally open), COM (common) and NC (normally closed).
While the relay coil is not energised, the COM contact touches the NC contact. While the relay coil is energised, it acts as an electromagnet and pulls the COM contact so it touches the NO contact. Therefore, when the coil is energised, the COM contact "changes over" (hence the name) from the NC contact to the NO contact.
Diodes D1 and D2 suppress "back EMF" from the relay coils - a large voltage spike that the coils generate when the current flow is interrupted. Without them, this voltage spike will cause arcing and damage to the relay contacts inside the timers.
The contacts direct the 12V supply from the battery to the actuator. Here's how it works.
In the morning, when you want the door to open, the first timer activates K1. Current flows from the +12V rail into the top COM pin on K1, out the NO pin, and down to the "fully extended" limit switch.
When the door is not fully open yet, this limit switch is closed, i.e. it completes the circuit. So the positive supply is connected to the black wire of the actuator.
I believe (but can't be sure) that positive to black wire makes the actuator extend.
The rest of the circuit is completed by the bottom contact of K1, which connects the actuator's red wire to the 0V rail (back to battery negative).
So the actuator sees 12V DC from the battery, with positive to black and negative to red. As I said, I believe this polarity makes it extend, but the documentation on the PA-14 actuator is very poor and this information is not stated anywhere! (Not even in the limit switch wiring diagram that they supply, which is also very poor quality.)
When the actuator is fully extended and the door is fully open, the "fully extended" limit switch becomes open-circuit and the power to the actuator is cut off.
Diode D3 conducts in the direction of the arrow, so in this situation, current will not flow through it. (This assumes that current flows from positive to negative, aka "conventional current".)
The door close circuit is a similar arrangement using K2. But K2 gets its +12V and 0V feeds from the NC contacts of K1. This ensures that if, for some reason, the timers both activate at the same time, K2 cannot feed current to the actuator while K1 is already driving it in the opposite direction. If that happened, the battery would be shorted out.
So when K1 is not energised, +12V and 0V emerge on the two NC terminals, and feed the COM terminals of K2. When the second timer activates in the evening, K2 activates, and supplies this voltage to the actuator, but with the opposite polarity.
The polarity of the voltage across the two wires in the morning and evening is marked on the diagram, just below K2.
In this case, the actuator receives positive on the red wire and negative on the black wire, which I believe will make it retract.
D3 now conducts, because current is flowing through it in the direction of the arrow. This means that the "fully extended" limit switch has no effect on the supply to the actuator. Since the full actuator current flows through D3 I have recommended a diode rated for 10 amps.
I am assuming that the actuator contains its own limit switch and will stop automatically when it is fully retracted. This is not stated anywhere in the description for the actuator, so you'd better check it!
D4 and D5 are two back-to-back 18 volt, 5 watt zener diodes. These are intended to suppress the "back EMF" that is generated by the motor when the supply to it is turned off. This back EMF could reduce the lifetime of the K1 and K2 contacts by causing arcing. C1 is also for noise and spike suppression.
I hope that's clear enough for you to follow.
There are a few unknowns related to the PA-14 actuator, which is very poorly documented. My main questions are:
1. What polarity is correct for extend, and for retract? I have assumed that red positive, black negative makes it retract, and the opposite makes it extend. This is based on the limit switch wiring diagram on the manufacturer's web site, which is also very short on information, so it could be wrong. If it turns out to be wrong, just swap the wires to the actuator.
2. Does the actuator include a limit switch for the retraction direction? I assume it does, but this is not stated anywhere in the documentation.
Here is a description of the parts needed.
K1,2: relays (socketable, with bases if necessary), with: Coil 12V DC; Contacts DPDT (double pole, double throw) (also called DPCO, double pole changeover), rated for 10A at 24V DC.
D1,2: 1N4007 http://www.digikey.com/product-detail/en/1N4007/1N4007FSCT-ND/965481 USD 0.18 x2
D3: 10A02T http://www.digikey.com/product-detail/en/10A02-T/10A02-TDICT-ND/2242770 USD 0.70
D4,5: 1N5355B http://www.digikey.com/product-detail/en/1N5355BG/1N5355BGOS-ND/1474101 USD 0.53 x2
C1: 4.7 µF 63V film capacitor http://www.digikey.com/product-detail/en/R82CC4470AA30J/399-6028-ND/2704682 USD 2.30
Any questions, ask away
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Thanks Kris!!
I have ordered the actuator and parts from DigiKey. Still need to find the relays and get them ordered. I am getting hung up on the "rails". If I'm not mistaken I am going to need a 12v rail and a 0v rail? Do you have recommendations on what type I should purchase? I have never dealt with anything regarding rails before.
I also have a question on the limit switch that you have in the diagram. Is this switch external from the actuator itself? If so will this cause issues with the fully open limit switch in the actuator. The tech for the actuator told me that the stroke will fully extend and then when i reverse the polarity it will retract. Not sure if that helps much.
I have ordered the actuator and parts from DigiKey. Still need to find the relays and get them ordered. I am getting hung up on the "rails". If I'm not mistaken I am going to need a 12v rail and a 0v rail? Do you have recommendations on what type I should purchase? I have never dealt with anything regarding rails before.
I also have a question on the limit switch that you have in the diagram. Is this switch external from the actuator itself? If so will this cause issues with the fully open limit switch in the actuator. The tech for the actuator told me that the stroke will fully extend and then when i reverse the polarity it will retract. Not sure if that helps much.
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"Rails" are just a way of describing parts of a circuit that have multiple connections between them. They aren't necessarily physical things! Sorry for the confusion.
More complicated circuits, shown as schematic diagrams, usually have the positive and 0V rails drawn horizontally across the top and bottom of the diagram, so they look like rails on the diagram.
But when components are connected to the 0V rail or the 12V rail, it just means that they all need to be connected together somehow.
The exact way you construct the circuit is up to you. Since the relays have bases with screw terminals, you could use these as connection points for wires and components.
For general ways of connecting things together, you can use "chocolate block" connectors (http://www.jaycar.com/productView.asp?ID=HM3196) or www.jaycar.com/productView.asp?ID=HM3169. There are other systems as well. If you have an electrical supply shop with knowledgeable, experienced staff (in other words, not Radio Shack or similar), tell them what you want to build, show them the diagram, and see what they suggest.
You need a limit switch for each direction. You need a "fully extended" limit switch, and a "fully retracted" limit switch. These are needed to stop the motor when the actuator reaches its limit. I had assumed that the "fully retracted" limit switch was built into the actuator.
The limit switch in my diagram is to detect when the actuator is fully extended, so that it doesn't extend too far, and (presumably) fall out, or do something else bad. I assume that the limit switch in the actuator detects when it's fully retracted.
If the actuator has two limit switches built into it, so the motor will turn off if it tries to extend too far, or retract too far, then you don't need the external limit switch at all. I assumed one was needed because the web site has a wiring diagram for one. But if both limit switches are built into the actuator, that simplifies things. In that case, just delete D3 and the switch, and join the wire straight through.
More complicated circuits, shown as schematic diagrams, usually have the positive and 0V rails drawn horizontally across the top and bottom of the diagram, so they look like rails on the diagram.
But when components are connected to the 0V rail or the 12V rail, it just means that they all need to be connected together somehow.
The exact way you construct the circuit is up to you. Since the relays have bases with screw terminals, you could use these as connection points for wires and components.
For general ways of connecting things together, you can use "chocolate block" connectors (http://www.jaycar.com/productView.asp?ID=HM3196) or www.jaycar.com/productView.asp?ID=HM3169. There are other systems as well. If you have an electrical supply shop with knowledgeable, experienced staff (in other words, not Radio Shack or similar), tell them what you want to build, show them the diagram, and see what they suggest.
You need a limit switch for each direction. You need a "fully extended" limit switch, and a "fully retracted" limit switch. These are needed to stop the motor when the actuator reaches its limit. I had assumed that the "fully retracted" limit switch was built into the actuator.
The limit switch in my diagram is to detect when the actuator is fully extended, so that it doesn't extend too far, and (presumably) fall out, or do something else bad. I assume that the limit switch in the actuator detects when it's fully retracted.
If the actuator has two limit switches built into it, so the motor will turn off if it tries to extend too far, or retract too far, then you don't need the external limit switch at all. I assumed one was needed because the web site has a wiring diagram for one. But if both limit switches are built into the actuator, that simplifies things. In that case, just delete D3 and the switch, and join the wire straight through.
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I follow now. I was thinking this was the case, but when I typed in 12v rails into google it started spitting out physical PSU's. I figured it was time for me to start asking the question before purchasing things that I don't need. I am going to call the tech on the actuator again to make certain that it does have a "open/close" limit switch that will kill the actuator when it is reached.
I didn't think about using those types of connectors. That will definitely make it easier on me.
I didn't think about using those types of connectors. That will definitely make it easier on me.
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When you call the tech, you could suggest that they should mention the limit switches somewhere in their documentation! The quality of their documentation is pretty poor.
Here is the response that I got back from the tech. Looks like I should be all set with eliminating the external limit switch, unless I need it to travel less than 12".
"HI Bob,
Yes you are correct, when the actuator reaches 12" of stroke it will cut the power automatically. The same will happen when it is fully retracted. These built in limit switches are non adjustable.
What you probably saw was a wiring diagram that shows how to wire an external limit switch."
"HI Bob,
Yes you are correct, when the actuator reaches 12" of stroke it will cut the power automatically. The same will happen when it is fully retracted. These built in limit switches are non adjustable.
What you probably saw was a wiring diagram that shows how to wire an external limit switch."
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Right. If you want to use the full stroke length, you don't need an external limit switch. Is 12" enough? Don't you need the door to open wider than that?
I have purchased one that has a longer stroke length. That just happened to be the one that I had opened in my browser when emailing the tech. Just received confirmation from digikey that my order has been shipped. Should be receiving all the parts next week and hopefully start wiring it up for a test run. I'm getting excited, but at the same time nervous of wiring this up and possibly wrecking something.
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Cool! I'm looking forward to hearing how it goes. Good luck!
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See
1. http://www.powerstream.com/Wire_Size.htm
2. http://www.amplepower.com/primer/gauge/
3. http://www.engineeringtoolbox.com/amps-wire-gauge-d_730.html
The maximum expected current is 5A. In this case I would design for at least twice that. According to (1), 20 AWG can carry 11A but based on voltage loss for a total circuit length of 10 feet or less, (2) recommends 14 AWG. So assuming the total length of each circuit is 10 feet or less, I recommend 14 AWG or thicker.
1. http://www.powerstream.com/Wire_Size.htm
2. http://www.amplepower.com/primer/gauge/
3. http://www.engineeringtoolbox.com/amps-wire-gauge-d_730.html
The maximum expected current is 5A. In this case I would design for at least twice that. According to (1), 20 AWG can carry 11A but based on voltage loss for a total circuit length of 10 feet or less, (2) recommends 14 AWG. So assuming the total length of each circuit is 10 feet or less, I recommend 14 AWG or thicker.
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All of the points in the diagram that have the 0V symbol (the symbol at the bottom of the negative wire from the battery) need to be connected together. This includes the negative terminal of the battery. Whether or not they are also connected to "ground" (i.e. the soil) is not important.
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Yes, both of the normally closed contacts on K2 are "no connection" (hence the "NC" marking).
Well spent some time and got it all hooked up per the diagram. At least that is what I think. Plug in the battery and could hear a relay click. Set the timer and hit test. The timer is displaying "short". Going to sleep on it and try again tomrrow. Maybe I over looked something.
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If you don't get anywhere, uploading some photos would be a good next step.
Small image, but should work for my question. I just want to make sure that I am looking at the contacts correctly. I know that the bottom contacts 7 and 8 are for the coil. Looking at the left side does it go...
1. NC
3. NO
5. COM
Then the right side....
2. NC
4. NO
5. COM
I threw all this together last night just to try and make it work. I did not solder in the diodes. I just stripped back some of the wire and then wrapped and crimped the diodes to the wire. I did try and solder in the capacitor and it is holding strong to the wire, but I will admit, my soldering skills are terrible. The zenger diodes I did the same by twisting the middle of them together and then twisting them into the two wires at the ends. Do you think that this could be causing the "short" since I did not take the time to make solid connections?
1. NC
3. NO
5. COM
Then the right side....
2. NC
4. NO
5. COM
I threw all this together last night just to try and make it work. I did not solder in the diodes. I just stripped back some of the wire and then wrapped and crimped the diodes to the wire. I did try and solder in the capacitor and it is holding strong to the wire, but I will admit, my soldering skills are terrible. The zenger diodes I did the same by twisting the middle of them together and then twisting them into the two wires at the ends. Do you think that this could be causing the "short" since I did not take the time to make solid connections?
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