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Switch needs to remain on for certain time

Ryan R

Mar 16, 2017
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Mar 16, 2017
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Hello all electronic peoples, I had a quick question

I am running a 12V DC Motor that I need to remain on for approximately 30-40 seconds when a button is pushed only once.
I can currently do this by holding the button, but I need to be able to simply push the button once and for it to run the circuit. The button also must return to it's original position.
This circuit must be pretty tight, so running a board with a 555 or other chip will be difficult.
Are there any switches that remain on for a certain amount of time, or slowly return to their original position while keeping the circuit closed?

Thank you all for your help
 

Bluejets

Oct 5, 2014
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I would have thought a 555 monostable perfect for this application.
What do you mean by "the circuit must be pretty tight", never come across that one before.
 

Ryan R

Mar 16, 2017
3
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Mar 16, 2017
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I would have thought a 555 monostable perfect for this application.
What do you mean by "the circuit must be pretty tight", never come across that one before.

The space where the circuit must be is very slim. I can only fit a switch and wires. I do not think that I can fit a board with a 555 on it
 

duke37

Jan 9, 2011
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Please show a picture of the space you have. I would think that a circuit could be quite small. A 555 may not be able to control the motor so you will need a relay or mosfet. What is the load this circuit has to supply?
For a 555, the biggest component will be a timing capacitor.
 

SalRu

Mar 16, 2017
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Mar 16, 2017
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Hi,

The 555 is the smallest solution you can find, i think.

You can try to make a double layer prototype PCB and use a NPN transistor to drive the motor

Hope to be helpful!
 

AnalogKid

Jun 10, 2015
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For a 555, the biggest component will be a timing capacitor.
Depends on the motor current. If this is a tightly sealed space, he might need a TO-220 motor driver to handle the transient heat.

ak
 

Ryan R

Mar 16, 2017
3
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Mar 16, 2017
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Thanks everyone for you ideas. The motor is a 12V motor that is being used for an aquarium pump. I did some research and I decided to go with the 555 monostable.
Thanks again!
 

Audioguru

Sep 24, 2016
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Sep 24, 2016
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Some children's toy dragons have a small slim pcb with a blob-on-board that blinks two LEDs 32 times (about 15 seconds) then shuts off. Its 4.5V outputs can be added and fed to a logic level Mosfet.
 
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