Wireless 5 Volt relay off timer

Discussion in 'The Projects Forum' started by vincenix, Dec 1, 2015.

  1. vincenix

    Thread Starter New Member

    Dec 1, 2015
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    I have a radio frequency remote control pair using a 5 Volt DC relay to control a 6 Volt DC, 7mm throw, pull solenoid.
    I wish to add a mono-stable, one shot, off timer circuit in the wireless relay circuitry to control the on time of the pull solenoid.
    Solenoid on time is to be 10 seconds.
    Power is through a battery.
    Questions; does an RC circuit reset itself after one shot requiring another trigger to discharge again?
    I mean to say, if the remote receiver is triggered by the transmitter to put the relay into NC and energize he solenoid will the added RC circuit empty it's charge over time into the solenoid and when it is done and the solenoid relaxes back out will this action stop current flow through the remote control receiver from the battery allowing the wireless relay to relax back into NO ready for a separate trigger to empty the capacitor again or will it just oscillate?
    Summary: I need a wireless 6 Volt off after 10 seconds timed relay.
    The 6 Volt off timed relay units can be bought but are expensive so I wish to buy the un-timed remote pair and make a timer to fit it as simply as possible.
    12 Volt wireless timed relay systems are more common but too powerful, large and expensive for this project.
    Thanks for your ideas.
     
  2. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    Use a 555 timer circuit in monostable mode, you will need to retrigger it to get another delay pulse.
     
  3. MikeML

    AAC Fanatic!

    Oct 2, 2009
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    Is the relay inside the receiver? Or is it external to the receiver?

    Is the present connection such that you have to send one command to turn the relay on, and a different command to turn the relay off?
    If so, how do you propose to automatically clear the relay after a time delay?
     
  4. vincenix

    Thread Starter New Member

    Dec 1, 2015
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    Thank you for the reply.
    Would this 555 in mono-stable mode, RC circuit be wired in downstream of or after the remote relay or upstream of the relay?
    Do radio frequency remotes give a one shot square wave that ends after the relay is switched from NO to NC allowing the relay to reset back into NO or does current continue to flow through to the capacitor?
    I am hoping the remote switches the relay to NC which charges the capacitor which in turn slowly gives energy through a resistor to operate the solenoid then when depleted the capacitor is not charged again until the remote switches the relay to NC again repeating the cycle on demand. Is that how it can work?
     
  5. vincenix

    Thread Starter New Member

    Dec 1, 2015
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    The relay is integral to the receiver.
    The transmitter has 1 button the idea being to push the button, have the solenoid operate and after 10 seconds have the solenoid cease operation and spring back out.
    So my main issue it seems is how to hit a single button, energizing a radio frequency remote receiver to switch a relay from NO to NC and after 10 seconds to have the timer circuit stop the flow of current to the solenoid which stops current to the relay allowing the relay to go back into NO and ready for the next trigger from the RFRC.
    These can be bought. I got a 12 Volt one pictured on ebay ( DC 12v Relay Wireless Remote Control RF Switch On/off Switch + Delay Time Timer) that worked great until I shorted it out on my housing but I need a 6 Volt model to keep costs down since I do not need that much power anyway but $34 per is too much.
     
  6. MikeML

    AAC Fanatic!

    Oct 2, 2009
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    So now you get a contact closure from the relay for as long as the button on the transmitter is pushed?

    How much current does it take to operate the solenoid? \

    Is the 5V for the receiver derived from the 6V battery that operates the solenoid?
     
  7. vincenix

    Thread Starter New Member

    Dec 1, 2015
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    Yes as long as the button is pushed but in my instance I need to get a contact closure from the relay with a single push and release of the transmitter button where I am hoping the contact closes, sends current to the RC timer circuit which eventually runs out of power over a specified period of time deactivating the solenoid and then somehow the remote relay contact opens ready for another momentary pulse from the remote receiver circuit. They cal it "momentary" where you need to press and hold the button of remote to make the relay contact close and release the button to open the contact.
    Both toggle and momentary modes are motivated by a single relay, which means you can work these two modes with a single button remote
    as opposed to "latched" where one presses button A, the load is on; press button B, theload is off or "toggle" where you push the button once for on and once for off.
    I want to say here that the remote control relay timers I have bought work as a single button push and release where the timing circuit is activated by the radio frequency trigger pulse which closes the relay contact, the capacitor(s), (variable) resistor and 555 IC then work to keep the solenoid activated for my set time period and then stop the current to the relay which opens the contact leaving it ready for another "on" pulse so that effect is what I wish to accomplish by buying a ready made receiver and adding a timer to it where the relay contact opens up again by itself.
    The solenoid is rated at 6 Volts and 2 Amps
    Yes the power from the battery operates the receiver circuit and the relay and the timer and the solenoid.
     
  8. vincenix

    Thread Starter New Member

    Dec 1, 2015
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    How would I re-trigger it?
     
  9. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    you can trigger the 555 from the relay on the receiver, by taking a pulse from its contacts or coil.


    post the ebay item for the 6V device you want to buy
     
    Last edited: Dec 2, 2015
  10. vincenix

    Thread Starter New Member

    Dec 1, 2015
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    On Amazon.com
    RF DC 6V 1 Channel One Relay Wireless Learning Remote Control Switch Black&White
    [​IMG]
    This is a picture of what I bought to operate the timer I want to make because I do not need 12 Volts. I need to cut the cost of batteries and the size of the container.

    On ebay
    DC 12v Relay Wireless Remote Control RF Switch On/off Switch + Delay Time Timer
    This is what I bought with a timer in it but again I do not need the power size or cost of a 12 Volt system.
    It works well.
    [​IMG]
     
  11. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    easy, yes you can feed the trigger from the relay coil, or contacts
     
  12. vincenix

    Thread Starter New Member

    Dec 1, 2015
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    OK great. Feed the 555 trigger from the coil current. Thank you.
    So does that train look like this?
    Push button on transmitter. Transmitter sends RF signal to receiver.
    Receiver creates square wave pulse and closes the relay contact energizing the RC circuit through the 555 trigger pin which circuit operates the solenoid for the time needed and when the capacitor is depleted and de-actvates the solenoid the relay contacts open again automatically or have already opened during the timed duration? Do you know how that part works?
    Is a square wave, one shot receiver pulse the key to having the relay re-open/reset?
     
  13. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    Looks like the key fob has two buttons, one will energise the receiver relay, the other will switch it off,

    so you need to trigger the 555 from the relay contacts or coil feed, then your timer will time out after its delay.
     
    Last edited: Dec 2, 2015
  14. vincenix

    Thread Starter New Member

    Dec 1, 2015
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    Well it is true that the key fob has 2 buttons on one of the units but that is the form I have replaced with a 1 button unit for simplicity and safety but I require the action to be one shot and automatically reset to accept the next single shot minutes or days later depending on the user so a reset I read is in the 555 I remember and will that work to deactivate the relay until it is needed again?
     
  15. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    If your receiver is designed for a key press pulse on, then another pulse for off, your going to have to modify the receiver to reset after its triggered the 555,

    I would use a single button key receiver,
     
  16. vincenix

    Thread Starter New Member

    Dec 1, 2015
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    I appreciate your attention to my issue.
    I have a single button transmitter that goes with the 6 Volt receiver I have settled on and I need to know how to reset the relay after it goes to NC from it's steady state of NO in order to operate the 6 Volt solenoid through a timer circuit. After the timer circuit finishes I want the relay to be in NO ready for the next pulse to close the relay contact into NC again so as to start the process all over the next time I need to operate the solenoid.
    So the question is how does one reset a NO relay from it's energized state of NC. Is this done through the 555 reset pin #4?
     
  17. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    the 555 times out and puts its own relay back to normally open,

    I take it you want to press your keyfob and activitie the 555,it then times out, then you can press the keyfob again to give another pulse to the timer,?
     
  18. vincenix

    Thread Starter New Member

    Dec 1, 2015
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    That is exactly what I am working toward.
    I press the remote button once, the unit activates the solenoid and after 10 seconds the unit deactivates the solenoid and is ready for the identical command and action once again over and over forever in a perfect world or until the owner dies or throws the unit away.
     
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