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Discussion in 'Power Electronics' started by Goldhelmeth, Apr 15, 2020.

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  1. Goldhelmeth

    Goldhelmeth

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    Apr 8, 2020
    Hello,

    I am a bit confused by relays... I want to power a 12v actuator with a 12v 4 channels bluetooth relay that is powered by a 12v battery...

    Can I do that and if yes can I direcly plug the 12v battery into the relay and when a channel is activated, will it deliver 12v ?
     
  2. Nanren888

    Nanren888

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    Nov 8, 2015
    Does the actuator specify a current? Does the 12v 4 channel relay specify a maximum current?
     
  3. Bluejets

    Bluejets

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    Show details of all of the above.
    Links will be fine as long as it shows their specs.
     
  4. Goldhelmeth

    Goldhelmeth

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    Apr 8, 2020
    the battery is 12v dc 7ah
     
  5. Bluejets

    Bluejets

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    Oct 5, 2014
    Relays can handle 10 amp.
    Actuator is 3 amp.
    No problem there......with the 12v 7ah battery, how long do you intend to run it..??

    Bit of daja vous here...could swear I've seen this query just recently.
     
  6. Goldhelmeth

    Goldhelmeth

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    Apr 8, 2020
    But how do I link all of it because on another forum how do I link the battery to the relay ?
     
  7. Goldhelmeth

    Goldhelmeth

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    Apr 8, 2020
    Because on another forum they told me it was not possible... Yes I have made a similar question but it was a bit different so I decided to make a nrw one
     
  8. hevans1944

    hevans1944 Hop - AC8NS

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    You have to create a circuit, consisting of the 12 volt battery, contacts on one of the four relays, and the actuator. If you are going to use all four relays (for whatever purpose), you need a circuit for each relay. A circuit is a closed conductive path from one terminal of the battery, then through a pair of contacts on the relay to one terminal on the actuator. The circuit is completed by connecting the other terminal of the actuator to the other terminal of the battery. If you are having difficulty understanding what a circuit is, please visit this Google result page to learn about circuits. The battery can supply power to four (or more) circuits simultaneously, said circuits being in parallel with the battery terminals.
     
  9. Goldhelmeth

    Goldhelmeth

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    Apr 8, 2020
    And what powers the relay ?
     
  10. Harald Kapp

    Harald Kapp Moderator Moderator

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    See the 2 pin connector at the lower left side of the PCB where it states VIN and GND? That is where you connect 12 V (the "technical data" - not really worth that denomination - specifies 9 V ... 13 V. That would be the power supply for the board, the relays on it and the radio module).

    The contact side of the relays is suitable for "control voltage:AC 85-265V 10A; DC 1-48V 10A" as stated in the technical data. The contact side is available on the blue connectors next to the relays, opposite the radio module.
     
  11. hevans1944

    hevans1944 Hop - AC8NS

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    I will repeat what I said earlier: learn about circuits.

    You can share the 12 V DC power provided to the Bluetooth relay module with the power supplied to its switched relay contacts to operate your actuator. The Bluetooth module is one circuit. The relay(s) and actuator(s) are another circuit(s). The 12 volt battery is common to both circuits.

    Except for the price, the links you provided for the Bluetooth relay module and the Battery both point to the same wireless Bluetooth module. Probably doesn't make any difference as long as the 12 V battery has enough current capability to power both the module and the acutator at the same time.

    Draw us a schematic (connection diagram) on a piece of paper, photograph it with your cell phone, then upload it with you next comment. Members here will look at it and advise you of any changes, if any, you need to make. Make sure your picture is in focus and that what you drew on paper is clearly visible in the photograph.

    Also, please do not "fork" your thread by posting the same subject twice (or more) using different titles. Moderators, if they catch this, will combine the threads, but why waste their time when you can do it yourself?
     
    Last edited: Apr 16, 2020
  12. hevans1944

    hevans1944 Hop - AC8NS

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    Jun 21, 2012
    You did. This thread is a fork of a previous thread started by @Goldhelmeth.
     
  13. Goldhelmeth

    Goldhelmeth

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    Apr 8, 2020
    Thank you for your answers,

    I will make a draw of the circuit I have in mind... Yes had started a thread were I was asking questions about powering an actuator, so they are quite different
     
  14. Harald Kapp

    Harald Kapp Moderator Moderator

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    @hevans1944 ; Hop, in my view these two threads are related, well observed, but different in content so a new thread is acceptable in this case.
     
    davenn likes this.
  15. hevans1944

    hevans1944 Hop - AC8NS

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    Okay, fine with me. Below are my thoughts on why I thought this thread is a fork of the previous thread.

    I thought this thread and the previous thread was about a project. My bad. @Bluejets comment in post #6 about deja vu led me to find the previous post from which I thought this thread was forked. @Goldhelmeth in post #14 maintains the two threads are quite different because different questions are asked. It is true the questions are different, but I still believe the questions in both threads concern the same project, which of course the OP hasn't bothered to discuss. We still don't know what he (or she) is trying to DO!

    In this thread the question is asked: how to connect an actuator, a relay, and a battery together. The previous thread asked if the battery (now updated to more Ah capacity) could power the same actuator for (presumably) the same project. Therefore, it seemed to me that this thread was just a continuation of the previous thread on the same project, except now we have a 4-channel Bluetooth remotely operated relay thrown into the picture and more questions. A dialog about the project in other words.

    Perhaps @Goldhelmeth could start a third thread where he asks how to reverse the actuator...? Maybe a fourth thread on how to install limit switches? And so on, never mind this is may all be about the same project. Threads sometimes do wander off-topic, but it is nice to have some continuity in the dialog. There is no evidence yet that @Goldhelmeth has learned anything about circuits, whether that is about "Powering a linear actuator with a battery" or simply "Relays" as this thread title appears to concern.

    Oh well, I can easily follow wherever this goes and however many threads are started by @Goldhelmeth. Looking forward to some nice photographs and perhaps some schematic drawings further along this path. It's fun to help beginners, and @Goldhelmeth does seem willing to learn.

    Backing into my cave now.
     
    Goldhelmeth likes this.
  16. Goldhelmeth

    Goldhelmeth

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    Apr 8, 2020
    Correct it is for the same project, yet if the questions are differents so will the answers be... I feel sorry that you felt it was necessary to start an argument, quite involved for a caveman if I may... Reverse an actuator ? Now now do not tempt the devil my friend. Evidence ? I hope the prime minister isn't concerned about my knowledge of circuits, as a matter of fact (you seem to enjoy them)why would I make such a simple query if I knew anything about circuits ! Yet I do understand your reaction and I would be delighted to join these poor threads, but once again ignorance is the enemy... How do I combine two thread ?

    Thanks I will provide the schematic soon (excuse my orthograph, I am french)
     
  17. hevans1944

    hevans1944 Hop - AC8NS

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    You don't, only a moderator or the owner of this forum (either one) can do that.

    If you were to ask a moderator to do combine two or more threads, you would need a NEW subject or title that is representative of the project the combined threads discuss. For example, let us just suppose that the reason you want to have a remote-controlled, battery operated, actuator is because you want to DO this: build an remote controlled door. If so, maybe a suitably descriptive (although not very informative) title could be: "Please help with my project to build a battery-operated, Bluetooth remote-controlled, door." A moderator might shorten that to: "Remote-controlled door."

    During the discussion thread, more details will (hopefully) be revealed. However, it is generally a good idea to supply as much information up front instead of doling it out in small pieces later, as if grudgingly guarding state secrets.

    That should be broad enough to cover a wide ranging dialog of HOW to do it. The purpose of such a dialog is to exchange ideas and come up with possible "solutions" that you may not have considered yet. Keeping everything in one thread allows a new visitor to the thread to go back and "come up to speed" on what has been previously discussed and to see where the discussion is going. This new visitor might even join into the discussion. It was not unusual in the past to have such threads exceed two hundred or more posts before finally being resolved, or dying for lack of interest. Unfortunately, I don't see much of that anymore. Drive-by posters seeking quick fixes seem to be increasing. Please don't be one of them!

    So, ask to have your threads joined, or not, for your project. Makes no difference to me, now that moderator @Harald Kapp has spoken. And I was not arguing. I was simply stating my point of view. Take it or leave it. C'est la vie.

    I suspected that French, rather than English, was your native tongue. I believe Harald's native tongue is German, and at least two other moderators speak a recognizable version of English, bastardized in Australia in much that same way that my English was bastardized in America. Even the British sometimes speak idiomatic English, perhaps more so than either the Aussies or us Yanks. The Canadians probably speak the purist form of English, isolated as they are between the Arctic Circle and the northern border of the USA. I see a LOT of Canadian license plates on cars here in Florida during the winter months (we call them Snowbirds), and their occupants speak English quite well. This forum is conducted in English and your English is more than passable, but there may be still be some misunderstanding with regard to idioms and context. Time will tell.

    The important thing is to have FUN!

    If you learn some electronics along the way, and this new-found knowledge encourages you to take it up as a hobby, you too will have lots of FUN.
     
    Last edited: Apr 17, 2020
    Harald Kapp likes this.
  18. Harald Kapp

    Harald Kapp Moderator Moderator

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    No argument here, all is well. No need to worry ;)
    I can do this, if you request it. But it is imho not necessary.

    Salut

    Harald
     
  19. hevans1944

    hevans1944 Hop - AC8NS

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    Jun 21, 2012
    "Relays" is always a good topic for beginners. They do come in handy for controlling all sorts of things. There are basically two types of relays available to the hobbyist today: electro-mechanical and solid-state. These both come in a variety of operating voltages used to actuate or energize the relay, a variety of switching voltage capability and a variety of switching current capability. In addition, electro-mechanical relays offer a variety of contact configurations. Solid-state relays typically only offer one switching configuration and one contact configuration.

    The 4-channel Bluetooth remote-controlled relay module that @Goldhelmeth has selected for this project uses four electro-mechanical relays, each independently actuated (energized) by means of a specific remote channel of a Bluetooth data communications radio-frequency link to either a four-button key-fob or another device (such as a cell phone) "paired" to the Bluetooth module. The details of how this works are complicated, but the knowledge required to use the module does not require knowing all about Bluetooth. All that is required is a cell phone with Bluetooth capability and an app (application program) that provides the user with a human-machine-interface (HMI) to the relay module.

    Each relay on the module has one set of Form C contacts, the most common contact implementation. Form C contacts have a common contact that the electro-mechanical relay can physically move with an electromagnetic coil to close a conductive path between the common contact and one of the other two contacts. When the relay is not actuated (energized), the moving contact rests on the normally closed or NC contact. When the relay is actuated (energized), the moving contact moves to rest on the normally open or NO contact.

    A circuit can be completed with either the moving contact and the normally-open contact (typical usage) or with the moving contact and the normally-closed contact. It is possible to connect both the NO and the NC contacts to separate circuits, but both cannot be closed simultaneously by the common moving contact, except in the special case of a relay constructed with "make before break" contacts, which is not the case here. I mention it only for completeness, and perhaps to forestall any comment by overly pedantic readers who might comment that I forgot about make before break relay contacts.

    Relays have a long history with the switched telephone networks, sometimes affectionately called POTS (Plain Old Telephone System). Telephone relays typically have long, slender, electromagnetic coils that attract a moving armature when the coil is energized. The armature then simultaneously moves many thin, flat, conductive metal springs mounted adjacent to the coil with contacts attached to their ends, and sometimes with contacts attached at other places along the flat spring. It is the unique mechanical construction of this stack of flat springs and their contacts that allows some really strange contact behavior when the relay is energized and de-energized. We will not further discuss this here because such relays are obsolete and not used anywhere except in developing countries that cannot afford a POTS network with solid-state relays... and also maybe used by few die-hard electronics enthusiasts who just happen to like them and who, with the aid of steering diodes, managed to design and build complicated logic machines using diode-relay logic late in the previous century, before changing over to TTL, CMOS, and microprocessor designs.

    So, your actuator will use one or more of the relays on your Bluetooth remote-operated relay module to connect to the battery that will supply power to the actuator. You could directly connect the two wires on the actuator to the two terminals of the battery and the actuator motor would run, but where is the fun in that? The actuator would extend (or retract) until it reached a mechanical limit, whereupon it would stop and the motor would stall, drawing its "locked rotor" current, which is generally much higher than the current required to move the actuator rod under its maximum-rated load. Some actuator circuits can sense the increase in current when their motor stalls and use this information to perform some corrective action, such as reversing the motor direction or shutting off current to the motor until its direction is reversed. Your actuator has a DC motor, likely a permanent magnet DC motor with brushes to carry current to its rotating armature. The motor is reversed by reversing the polarity of the voltage applied to the two motor leads by the battery. I don't see that you have purchased or specified any components that would allow you to sense actuator motor current or actuator limit positions, so you will just have to accept whatever consequences occur when the actuator reaches an extension or retraction mechanical limit stop.

    There is a simple switching (relay) circuit that you can interpose between the battery power source and the motor leads to effect a polarity reversal when the relay changes state, from energized to de-energized or vice versa. Unfortunately this switching circuit requires two sets of Form C contacts that operate in unison on a single relay. I suspect your Bluetooth module cannot guarantee this will happen when two sets of Form C contacts on two separate relays are used. There will be a slight delay upon energizing or de-energizing the two relays, and one set of relay contacts will open or close before the other set. This could lead to a short-circuit of your battery and that is never a good idea.

    So, the simple circuit probably won't work for you. However, since you have four independent Form C contacts available on four relays, it is a relatively trivial matter to connect the contacts in such a manner that energizing two relays in sequence will power the actuator in one direction, while de-energizing those two relays and energizing the other two relays in sequence will power the actuator in the opposite direction. Of course, all four relays are never actuated simultaneously. And when all four relays are de-actuated, power is completely removed from the motor and it stops.

    Perhaps @Goldhelmeth can draw and post a schematic of how this will work...
     
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