Switching ON a 12Vdc motor for 15 seconds every day at a specific time

In summary: But yeah, I'm thinking the microcontroller would be the way to go. The other problem (or perhaps not problem) is that I'm not sure what the OP means by "pulse". Is it just a single pulse, i.e., turn on for 15-20 seconds, turn off, and never turn on again until the next day, or is it more of a cycling on and off?EDIT: The problem with the microcontroller is that I don't know if it's cheaper than a timer unit. It's probably not much more expensive than a digital timer, but if you want something simple, cheap, and robust, I don't think you can beat the old analog timers that you just
  • #1
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Hi guys,
My problem is that i have a motor that needs to be turned ON once, every day at a programmable time and for a duration of 10-20 seconds. The power of the motor is bellow 80W.
I have searched throught the net on Merlin Gerin, Schrack and similar catlogues but can't find any programmable time switch that can run in a pulse mode and also on 12VDC (i have a batterie that has to drive the motor and the timer). Usually they have those time switches on 230Vac but i need 12Vdc... Can somebody help me??

To conclude - the facts:
- 12Vdc power supply
- once a day at a specific programmable time to turn ON the motor
- power of the motor is bellow 80W and it is running on 12Vdc also
- duration of the pulse is between 10 and 20 seconds
- it needs to be as simple as possible (in order to be also the cheapest possible)
- it needs to be ready build - not a diy thing (maybe something similar to this: http://www.hugo-mueller.com/weekly-time-switches/mueller-sc-08-11-paladin-172-110,p,en,1,1.html [Broken] )

thank You very much for any help You can give me
best regards
sunny
 
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  • #2
That is so specific that I doubt if you would find such a thing just by using Google.

It is not at all difficult to make one, but not if it is your first DIY project. Do you have someone who would have enough experience to make up a small circuit and connect it to mains wiring?

The easy way would be with a microcontroller. This is not as complicated as it sounds. It would just generate a 24 hour delay, put 5 volts on one of its pins, leave it there for 20 seconds and then turn it off and wait another 24 hours.
You could save a lot of complexity if you could start the process at the time you want the motor to come on one day and then it would come on at that time next day.

If you did want to program the time, you could get an garden irrigation timer and generate the 20 second power pulse from that. Again, no real problem, but you would have to know how to do it safely.
 
  • #3
I agree with vk6kro easiest way is probably with a microcontroller, assuming you know how to program and work with one.

However, a simpler solution may be to go to your local hardware store and buy a timer power unit (the things that turn on appliances, or your block heater, etc.--anything that's plugged into it). The old-style ones have hour(ish) resolution (or possibly 1/2 or 1/4 hour), but there are newer digital ones that may be able to give you down to the minute resolution (i.e. turn on at 8PM, turn off at 8:20PM).

You can use that to turn a relay with a 120 VAC (or whatever mains voltage is where you live) coil. And then splice your 12VDC loop into the relay such that it's interrupted whenever the relay switches off.

The other thing you may be able to do is to just plug in this unit directly to the power timer itself! You mention that it's 12VDC, and something about PWM, but is it being powered from a wall adapter, or through a power supply? If it's a battery, you might be able to find a suitable DC power supply that outputs the appropriate current.

EDIT: Something like this (or a digital version; again your hardware store should carry something like it):
http://www.intermatic.com/products/timers/consumer%20indoor%20timers/lamp%20%20appliance%20timers/tn311c.aspx [Broken]

EDIT2: Dammit, I read that as 15-20 minutes a day! Well, you could still use a similar setup, with a time delay relay set for interval timing (i.e. it fires only for a few seconds after a control pulse is applied), and you can turn it off whenever the timer is able to. For instance:
http://documents.tycoelectronics.com/commerce/DocumentDelivery/DDEController?Action=srchrtrv&DocNm=1308242_CB&DocType=DS&DocLang=EN [Broken]
 
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  • #4
MATLABdude, I think you need to read the op yet again. He clearly states that he needs to run the timer on the same 12vdc supply that runs the motor. I cannot think of an off-the-shelf solution for this either. As already stated, this would be an easy microcontroller project.
 
  • #5
TurtleMeister said:
MATLABdude, I think you need to read the op yet again. He clearly states that he needs to run the timer on the same 12vdc supply that runs the motor. I cannot think of an off-the-shelf solution for this either. As already stated, this would be an easy microcontroller project.

I have several inverters, 12 Volt to 120V (smallest is 40 Watts), a simple 2:1 stepup transformer will give 240V. If the OP is not able to connect a few wires, then a EE student, or local electrical service should be able to build the system.

Just a matter of connecting a few wires.
 
  • #6
The microcontroller still seems like the best bet to do precisely what was asked.

However, if the motor could run for 1 minute instead of 20 seconds, my sprinkler timer will give 1 minute turn on times. You can set an exact time to turn on. You can set it to turn on every day.

It runs on 24 volts AC but this is quickly converted to 5 volts internally so it would already run on 12 volts DC with slight modification. And it switches the sprinkler solenoids on with the same 24 volts AC via a relay, so it could switch 12 volts as well.

Depends on why the motor was being turned on and if 1 minute would be OK.
 
  • #7
Have you looked into "timing relays"? I've seen them in the McMaster-Carr catalog.
 
  • #8
TurtleMeister said:
MATLABdude, I think you need to read the op yet again. He clearly states that he needs to run the timer on the same 12vdc supply that runs the motor. I cannot think of an off-the-shelf solution for this either. As already stated, this would be an easy microcontroller project.

MATLABdude is a MATLABdud, and fails at reading comprehension. That's probably what happens when you're running on 0.5 to 4 hours of sleep a night for a week.
 

1. What is the purpose of switching ON a 12Vdc motor for 15 seconds every day at a specific time?

The purpose of this action is to automate a process that requires the motor to run for a short duration at a predetermined time. This can be useful for tasks such as watering plants, turning on lights, or activating a small appliance.

2. How is the 12Vdc motor controlled to turn ON for 15 seconds?

The motor can be controlled using a timer or a programmable microcontroller. These devices can be set to send a signal to the motor at the desired time, initiating the 15-second run time.

3. Can the timing be adjusted for the 15-second run time?

Yes, the timing can be adjusted by changing the settings on the timer or microcontroller. Some devices may also allow for manual adjustment of the timing.

4. Is it possible to switch ON the 12Vdc motor for longer than 15 seconds?

Yes, it is possible to adjust the timing to run the motor for longer than 15 seconds. However, it is important to ensure that the motor is designed to run for extended periods and that it is not at risk of overheating or causing damage to the system.

5. Can this setup be used for multiple motors?

Yes, this setup can be used for multiple motors by using a timer or microcontroller with multiple output channels. Each motor can be connected to a separate output, allowing for individual control and timing for each motor.

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