How can I build a stop/start timer into a 3 volt circuit? - Electronic Circuits Projects Diagrams Free

thiscountryside · 28th August 2009, 01:08 PM

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 · 28th August 2009, 02:44 PM

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 · 28th August 2009, 02:52 PM

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.

birdman0_o · 28th August 2009, 02:58 PM

Ok perfect
Heres what you want : 555 and 556 Timer Circuits
Feel free to ask any questions

thiscountryside · 28th August 2009, 03:26 PM

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!

birdman0_o · 28th August 2009, 03:32 PM

This should help:
LM555 Timer Circuits

ElectroNerdy · 28th August 2009, 03:37 PM

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.

birdman0_o · 28th August 2009, 03:45 PM

Using the link put R1 = 50, 000 R2 = 10, 000, 000 and C1 = 100 uF
Let me know if you like the results

birdman0_o · 28th August 2009, 03:48 PM

Quote:

Originally Posted by ElectroNerdy

Remember this equation:

. Note that when you increase the resistor value the discharge time will increase and if you increase the capacitor value it will increase the duration of the discharge.

V = Vo * e^-t/RC

thiscountryside · 28th August 2009, 04:21 PM

Brilliant, things are slowly starting to make sense, thank you. Mike, I like the results, thank you

thiscountryside · 28th August 2009, 04:46 PM

Hello again, can you get 10,000,000 resistors? keep reading stuff and they seem to stop at 1M...1,000,000?

thiscountryside · 28th August 2009, 04:48 PM

however I can change the capacitor to 1000uF rating and all is well?

birdman0_o · 28th August 2009, 05:38 PM

Yes you can go either way, 10M resistors exist though

Do you see how to hook up a transistor to your motor?

thiscountryside · 28th August 2009, 05:48 PM

hello, ok cool. do i need to hook up a transistor to the motor?

birdman0_o · 28th August 2009, 05:54 PM

Yes, the 555 will not be able to sink/source enough current for your motor

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28th August 2009, 01:08 PM	#1
thiscountryside	How can I build a stop/start timer into a 3 volt circuit? 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

28th August 2009, 02:44 PM	#2
birdman0_o	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. __________________ Mike My website: www.ElectroBird.net

28th August 2009, 02:52 PM	#3
thiscountryside	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.

28th August 2009, 02:58 PM	#4
birdman0_o	Ok perfect Heres what you want : 555 and 556 Timer Circuits Feel free to ask any questions __________________ Mike My website: www.ElectroBird.net

28th August 2009, 03:26 PM	#5
thiscountryside	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!

28th August 2009, 03:32 PM	#6
birdman0_o	This should help: LM555 Timer Circuits __________________ Mike My website: www.ElectroBird.net

28th August 2009, 03:37 PM	#7
ElectroNerdy	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.

28th August 2009, 03:45 PM	#8
birdman0_o	Using the link put R1 = 50, 000 R2 = 10, 000, 000 and C1 = 100 uF Let me know if you like the results __________________ Mike My website: www.ElectroBird.net

28th August 2009, 04:21 PM	#10
thiscountryside	Brilliant, things are slowly starting to make sense, thank you. Mike, I like the results, thank you

28th August 2009, 04:46 PM	#11
thiscountryside	Hello again, can you get 10,000,000 resistors? keep reading stuff and they seem to stop at 1M...1,000,000?

28th August 2009, 04:48 PM	#12
thiscountryside	however I can change the capacitor to 1000uF rating and all is well?

28th August 2009, 05:38 PM	#13
birdman0_o	Yes you can go either way, 10M resistors exist though Do you see how to hook up a transistor to your motor? __________________ Mike My website: www.ElectroBird.net

28th August 2009, 05:48 PM	#14
thiscountryside	hello, ok cool. do i need to hook up a transistor to the motor?

28th August 2009, 05:54 PM	#15
birdman0_o	Yes, the 555 will not be able to sink/source enough current for your motor __________________ Mike My website: www.ElectroBird.net