Need help constructing a timer relay

Discussion in 'The Projects Forum' started by Speedjayg, Dec 13, 2012.

  1. Speedjayg

    Thread Starter New Member

    Dec 13, 2012
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    I was reading some forums about the 555 timer and i have a problem somewhat related to it. I have a device that is motion activated that powers and Solenoid for approximately one second, my goal is that when the motion switch is activated that i can adjust the amount of time current is flowing through the electromagnet(maybe have current flow through the solenoid between 1-5 seconds). I was curious if there is anyway possible to have the current flowing through the electromagnet adjustable by time? Thank you in advance.
     
  2. #12

    Expert

    Nov 30, 2010
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    Sure. Here's how you do it.
     
  3. KMoffett

    AAC Fanatic!

    Dec 19, 2007
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    You sent me a PM, but have your profile is set to NOT receive PMs.
    Better to get your questions answered here.

    Can you post information on the motion sensor, the solenoid, and your power source.

    Ken
     
  4. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    Last edited: Dec 14, 2012
  5. DenzilPenberthy

    New Member

    May 28, 2012
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    Hi,

    If you want to save yourself having to design and build something, you can buy a ready made time delay relay. These are used a lot in industrial automation. It works just like a normal relay except there is a dial on the top that lets you select how long the relay stays energised for after you trigger it.

    Like this:
    http://uk.farnell.com/aromat-f-a/pmh-10m-ac120v/time-delay-relay/dp/1945520

    but you'll have to find one with suitable coil voltage and contact current/voltage ratings for your application.
     
  6. Speedjayg

    Thread Starter New Member

    Dec 13, 2012
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    Thanks for all the quick replies. I am trying to use a Purell Hand Sanitizing Machine and work off of that. I'm sure many have seen how these operate but there are two motion sensors at the bottom of the device and when your hand is underneath some soap is dispensed. I would like to be able to control the time current is flowing through the solenoid, so when i wave my hand under the device more fluid will exit. Here is a picture of the inside of the machine.[​IMG]
     
  7. #12

    Expert

    Nov 30, 2010
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    I would expect a fixed amount of soap per stroke, so time engaged would not change anything. Have you checked to see if this is designed so that your idea won't work?
     
  8. Speedjayg

    Thread Starter New Member

    Dec 13, 2012
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    Yes i have recently found out that and that has put an end to the previous idea. But i have a new thought that should be fairly simple but i dont know how i will wire up the motion sensors to it. I would like the motion sensors being a relay to turn on a timer circuit maybe like this one (http://www.apogeekits.com/interval_timer_555.htm) i want an adjustable timer, even though this is an interval timer i think it would work. Then from that timer circuit i could have it powering a 12v water pump (http://www.skycraftsurplus.com/12vdcminiwaterpump.aspx?gclid=CLz1htLunLQCFYw-MgodCAsA2g) So when the motion sensors pick up motion the pump distributes a certain amount of liquid.
     
  9. #12

    Expert

    Nov 30, 2010
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    Great! This almost makes up for the stupid answer I gave for "finding current" yesterday.:p
     
  10. Speedjayg

    Thread Starter New Member

    Dec 13, 2012
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    Haha that is alright:). But is there a way to run the motion sensors as a relay that turns on the timer circuit which in turn powers the pump for a set amount of time. I dont know if this is possible but i think the timer kit im going to get is (http://www.electronickits.com/kit/complete/timers/canck002.htm) but i want to get the schematics of the kit first. So overall is there a way to have the motion sensor trigger that kit?
     
  11. #12

    Expert

    Nov 30, 2010
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    That kit looks good. The first thing I would do is replace the capacitor with one that is a tenth the number of microfarads to cut the time down to 1 minute maximum, or even use 1% of the original size to cut the maximum time to 6 seconds. Get the drift?

    The next goal is to get the motion sensor to give the kit 9 to 12 volts DC. What voltage does the motion sensor deliver?
     
  12. Speedjayg

    Thread Starter New Member

    Dec 13, 2012
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    Thats a great idea reducing the Capacitor to cut the time down, because i only need the kit to run inbetween 2-3 seconds and need the intervals to be small. But one question i had about the kit maybe it is common sense answer but shouldnt the kit have an input holes and and output holes so 4 in total? Because i think i found the pump i want it runs of 6v-9v and i dont understand how i would hook it all up to that kit so when the motion sensors are tripped that the timer kit puts power out to the pump for around 3 seconds?
     
  13. #12

    Expert

    Nov 30, 2010
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    The 2 black pins on the bottom, next to the LED are the outputs. They will provide a voltage, the same voltage you gave the kit on the red and black wires. Problem: the 555 timer chip doesn't have the kind of ability it takes to run a pump. You are expected to provide a relay.

    What voltage does the motion sensor deliver? We're expecting you to tell US!
    What supply is conected to the motion sensor? Wall wart? Power line 120 volts?
    You might have to get your jolt meter out and measure it. AC? DC? How much?
     
  14. Speedjayg

    Thread Starter New Member

    Dec 13, 2012
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    As of now i do not own a device like this just yet i have one shipped out to me so i have not been able to run tests on the motion sensor. But what i do know is that the whole machine is powered by 3 C batteries. I was talking to my professor and i think we found a way to make this work. We would be using (http://www.velleman.eu/downloads/0/illustrated/illustrated_assembly_manual_k2579.pdf) for the timer which can handle the amount of amps and voltage the pump requires and the same pump (http://www.ebay.com/itm/Non-submers.../120983064864?pt=BI_Pumps&hash=item1c2b271120) and use the motion sensor as the start switch. Sorry i only know limited information but i wanted to make sure that the project was worth the time. Does that sound like it would work to you?
     
  15. #12

    Expert

    Nov 30, 2010
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    From what I can tell, the dispenser uses a bit less than 5 volts, the timer wants a solid 12 volts, and the pump prefers 6 volts (but will run up to 9V). This looks like (3) C batteries will operate a 5 volt relay that sends 12 volts to the timer, which then operates a relay that sends 6 to 9 volts to the pump. More than a little bit of level shifting.
     
    Last edited: Dec 18, 2012
  16. Speedjayg

    Thread Starter New Member

    Dec 13, 2012
    9
    0
    I understand your concern with level shifting i decided to get a 12V mini water pump. (http://www.skycraftsurplus.com/12vdcminiwaterpump.aspx) i called the company and they said the device is rated 700 ma. The person i talked to on the phone said the device will run on 12v DC 300ma like the kit will run off but maybe just a little slower. But now i am curious is there a way to run the motion sensor switch instead of the push button on switch. I do not have the device yet it is almost here, but if i put a big enough resister to knock the 12V down to around 4.5V like it had in the original machine would that work?
     
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