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  • AC Power Adapter Polarity

    I was given this link https://www.amazon.com/DIKOO-Adapter...s%2C217&sr=8-5 as an alternative to using 6 volt lantern batteries by the manufacturer of the device. (a battery powered photocell controlled door for chicken house) The good batteries are 15+ bucks a piece. Anyway, I'm trying to determine the polarity of the output. I thought I could use a volt meter, and verify polarity as in house line voltage, where voltage will read whether the ground is neutral or ground, but this doesn't. The plugs on this adapter are not polarity specific as most things are now with line voltage. So how would I determine the polarity before connecting?

    The device has 2 alligator clips that are black and red, and you simply clip to the right "spring". But I have to cut off the male end and strip back the insulation to expose the wires on this adapter, so how would I know which is which?

  • #2
    The red clip is the positive, the black the negative.

    I don't know what male connector you're talking about, but if you mean the tubular thing on the end of the wire on the supply, it's actually a female. The hollow centre is the positive, the sleeve the negative. Look at the second picture down on that Amazon listing. (That way around is the common convention, by the way.)

    Instead of just cutting off the female plug and then wondering which wire does what, why not just buy the matching male plug and solder it in place of the red and black clips on the other gadget's lead? Obviously, the wire that had the red clip on it would go to the centre pin, and the black to the other.
    Last edited by Mike Burch; 10-23-2021, 08:16 PM.

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    • #3
      It looks like a standard transformer based power supply. The transformer doesn't care which side of the outlet it is plugged in to, so just plug it in and go.

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      • #4
        Originally posted by SLK001 View Post
        It looks like a standard transformer based power supply. The transformer doesn't care which side of the outlet it is plugged in to, so just plug it in and go.
        I don't think that's his problem. It's the DC side of things that has him baffled, not the AC.

        Last edited by Mike Burch; 10-23-2021, 08:16 PM.

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        • #5
          I understand the center is the positive, and the outside is ground. The "fitting/plug" I need to cut off is the MALE end of the connection. I know all this. Once I cut the male connection off to strip the wires back, I was looking for a way to determine which is positive. The manufacturers info was specific to make sure the polarity was correct so not to damage the circuit board.

          Mike, your link doesn't work for me.

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          • #6
            Originally posted by Mike Burch View Post
            I don't think that's his problem. It's the DC side of things that has him baffled, not the AC.
            Actually, it looks to me like he's concerned about both input and output. Both questions have been answered. I might pay to note that I have seen factory power supplies with polarity reversed; the center was ground and the shell positive. Not common though.

            Southwest Utah

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            • #7
              Originally posted by rws View Post
              I understand the center is the positive, and the outside is ground. The "fitting/plug" I need to cut off is the MALE end of the connection. I know all this. Once I cut the male connection off to strip the wires back, I was looking for a way to determine which is positive. The manufacturers info was specific to make sure the polarity was correct so not to damage the circuit board.

              Mike, your link doesn't work for me.
              Cut it and odds are about 99% that the internal wires are red and either black or white. Red, as said, is positive. You can take a sharp knife and skim off a bit of the outer casing without cutting through the inside insulation and see for yourself.
              Southwest Utah

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              • #8
                Click image for larger version

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                It's all mind over matter.
                If you don't mind, it don't matter.

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                • #9
                  If you have this device, check the output with a voltmeter before using it. One of the Amazon reviews with images shows that the one he tried to use put out almost 28 volts and fried his appliance.
                  http://pauleschoen.com/pix/PM08_P76_P54.png
                  Paul , P S Technology, Inc. and MrTibbs
                  USA Maryland 21030

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                  • #10
                    If you want to know what the polarity of each of the two wires, then use your volt meter. If this fails, then read the volt meter manual. Your original problem may stem from your leads not being able to contact the center conductor. If you cut and strip the wires, this won't be an issue.

                    And further examination of the device itself, it is a switching power supply and NOT a transformer supply. Neither one of them care how they are hooked up to the AC line.

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                    • #11
                      OK, if I understand you correctly, you intend to keep the alligator clips on the alarm device but you need to cut the connector off the wire from the wall wart (adapter) and strip the wires so you can clip those alligator clips to them. And you want to know how you can know which wire is which after cutting them.

                      And you DO have a VOM (Volt-Ohm Meter).

                      First, you seemed to be talking about the connection to the house wall socket and the fact that it is not polarized. That does not make any difference in the polarity of the 6V DC output of the adapter. You can plug it in either way and the polarity of the output will not change. And this also has nothing to do with ground and neutral. If you plug it in either way, you will be connected to the hot and neutral of the house wiring and there will be NO connection to the safety ground. The adapter has sufficient protection that the ground connection is not needed.

                      After you cut the output wire on the adapter and strip the wires, you can use your VOM to check the polarity. Simply set the meter for "DC Volts" and if there is a range switch, set it for a 10 Volt range or higher. That should give you a reading with the 6 Volts the adapter produces. When the two test leads are connected so that the meter reads +6 Volts then they will indicate the polarity of the adapter wires. Assuming the black lead is connected to the "Common" on the meter and the red lead is connected to the DC input jack, then the red lead will be connected to the positive wire and the black lead to the negative.

                      If the meter leads are connected to the opposite polarity the meter will either read -6 Volts if it is a digital meter or if it is an analog meter the needle will move as far below zero as the movement allows. If this occurs, just reverse the meter leads.

                      I will add this: using the alligator clips on the stripped wire is close to the worst possible way to connect these two items together. In an outdoor environment, like a chicken coop, corrosion is sure to set in and you will be repairing it in short order. A much better way would be to strip both the wires from the adopter and the wires to the alarm device and splicing them. It would be best to solder them together and insulate that with some heat shrink tubing. I would use a double layer of the heat shrink tubing with the outer pieces both larger in diameter and longer than the inner ones. This would do a good job of keeping the moisture out of the joint for a fairly long time. If you can not solder them, then crimp splices would be my second choice but they would make sealing against moisture much harder: a liquid insulating compound could be brushed on. A simple twisted wire splice would be my last choice. If you can not use heat shrink for the insulation, electrical tape could be wrapped tight with multiple layers. Since this if for outdoor use, I would not recommend getting a socket to match the plug on the adapter: corrosion would rapidly get to that too.



                      Originally posted by rws View Post
                      I understand the center is the positive, and the outside is ground. The "fitting/plug" I need to cut off is the MALE end of the connection. I know all this. Once I cut the male connection off to strip the wires back, I was looking for a way to determine which is positive. The manufacturers info was specific to make sure the polarity was correct so not to damage the circuit board.

                      Mike, your link doesn't work for me.
                      Paul A.
                      SE Texas

                      And if you look REAL close at an analog signal,
                      You will find that it has discrete steps.

                      Comment


                      • #12
                        Originally posted by rws View Post
                        I understand the center is the positive, and the outside is ground. The "fitting/plug" I need to cut off is the MALE end of the connection. I know all this. Once I cut the male connection off to strip the wires back, I was looking for a way to determine which is positive. The manufacturers info was specific to make sure the polarity was correct so not to damage the circuit board.

                        Mike, your link doesn't work for me.
                        I didn't post a link.

                        The only male bit I can see on the adapter is the pins that go into the mains power socket on the wall.

                        The DC output cable appears to be permanently attached to the adapter. I see no male connector on that cable.

                        Paul's response is, as always, bullet-proof. Read, learn and inwardly digest. I'm sure he won't mind my adding that the best insulation for outdoor connections is self-amalgamating tape wound tightly over the heat-shrink. It's weather-proof, lasts for years and is relatively easily removed without leaving any residue. Brilliant stuff!

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                        • #13
                          If the meter leads are connected to the opposite polarity the meter will either read -6 Volts if it is a digital meter or if it is an analog meter the needle will move as far below zero as the movement allows. If this occurs, just reverse the meter leads.
                          Paul, you are correct. I stripped back both wires, and the voltage read with a negative when the polarity was reversed. I have it marked and will go forward. Thank you!

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                          • #14
                            Great suggestion on the tape. Thanks for improving my suggestion.

                            And I don't know about that bullet-proof thing. I think I have a flesh wound or two from past mistakes.



                            Originally posted by Mike Burch View Post

                            I didn't post a link.

                            The only male bit I can see on the adapter is the pins that go into the mains power socket on the wall.

                            The DC output cable appears to be permanently attached to the adapter. I see no male connector on that cable.

                            Paul's response is, as always, bullet-proof. Read, learn and inwardly digest. I'm sure he won't mind my adding that the best insulation for outdoor connections is self-amalgamating tape wound tightly over the heat-shrink. It's weather-proof, lasts for years and is relatively easily removed without leaving any residue. Brilliant stuff!
                            Last edited by Paul Alciatore; 10-24-2021, 08:32 PM.
                            Paul A.
                            SE Texas

                            And if you look REAL close at an analog signal,
                            You will find that it has discrete steps.

                            Comment


                            • #15
                              Great! Keep those chickens fed. Nothing like farm-fresh eggs. And the occasional Sunday chicken dinner. I had three sets of grandparents who kept chickens, one in the middle of the city.



                              Originally posted by rws View Post

                              Paul, you are correct. I stripped back both wires, and the voltage read with a negative when the polarity was reversed. I have it marked and will go forward. Thank you!
                              Paul A.
                              SE Texas

                              And if you look REAL close at an analog signal,
                              You will find that it has discrete steps.

                              Comment

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