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How can I build a stop/start timer into a 3 volt circuit?

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thiscountryside

New Member
Hello, How are you?

I am new to this forum and at the moment my knowledge of electronics is basic to say the least. I have built a simple 3 volt circuit that powers a 3 volt motor that bounces around randomly for an installation. I would like the motor to come on for 10 minutes then stop for 10 minutes (this time could vary and doesn't need to be exact).....can anybody help?

I thank you for your time

Dan
 

birdman0_o

Active Member
Using a lm555 to create a 10 minute astable pulse you probably can. However if you need exactly 600 seconds, then you will need to look for another solution. Gah I couldn't find the voltage range on the datasheet but I remember it going down to 3V and max 18V, somebody please correct me if I am wrong.
 

thiscountryside

New Member
Thank you for your reply, the timing does not need to be accurate to the second by any means, the time could in fact be random it's just that the motor needs to stop to rest and cool down and the batteries need to last as long as possible. If it rests for longer and suddenly springs back into life all the better. Apologies for not using technical terms.
 

thiscountryside

New Member
Hello Mike,
Thank you, ok, I'm struggling to figure out what resistors and capacitor would be suitable for periods of minutes on(eg 10 minutes) and minutes off (eg 8 minutes off) rather than seconds, the terminology is alien to me. Sorry, this is probably very basic stuff for you!
 

EN0

Member
Remember this equation:

T=RC

Where:

T=Time
R=Resistor
C=Capacitor

So let's say I have a 200KΩ with a 200µF capacitor. Well 200,000 x 0.0002 = 40s. So it will take approximately 40 seconds to discharge the cap. Note that when you increase the resistor value the discharge time will decrease and if you increase the capacitor value it will increase the duration of the discharge. Remember to expand all your numbers when you do it; you can't just do 200 x 200.

This equation is especially helpful when designing circuits for the 555 timer.
 

thiscountryside

New Member
Wow, this is getting complicated. At the moment I don't then. I need to do some more reading I think. Is there any other way of stopping and starting the circuit...a timed switch that cuts out after 10 minutes and has to be pressed again for example?
 

thiscountryside

New Member
yes, the motor will be in an installation so the viewer could press the button again and the motor would come to life, an automated system would be better but may be beyond me
 
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