Momentary or timed action

Madman

Madman

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I presently have two small animated freight cars. One is a mermaid swimming around an aquarium. The small motor is powerd by one AA battery. The second car has a radar antenae the spins via a Buhler motor that runs on a 9 Volt battery. I would like to fit reed switches to the bottom of each car so that the action would be activated as they pass over a magnet. However, I need some sort of simple circuitry or device that would keep power to the motor for a fixed length of time, say 20 seconds.
Any thoughts?
I found this; http://www.st.com/internet/analog/product/65434.jsp However I would need some guidance on how to incorpoate it into the circuitry.
Both cars can be seen here;
http://youtu.be/VYqFTLskTTo
 
I think you would need to operate that 555 chip in "monostable" mode.
An internet search including that key word may produce the info. you require. This may help http://www.kpsec.freeuk.com/555timer.htm#monostable < Link To http://www.kpsec.freeuk.c./555timer.htm#monostable
I suggest that in order to become familiar with the 555 chip in applications such as yours you consider purchasing an inexpensive kit of parts rather than just the chip. Here's a U.K. based example http://www.rapidonline.com/Education/555-Monostable-Project-W-Drive-Circuit-70-6016 < Link To http://www.rapidonline.co...-Drive-Circuit-70-6016
 
Thanks Neil. However I am having some difficulty understanding just how the kit would fit into the grand scheme. The kit alone is only a trigger or drive I presume. I was unable to determine how I would wire the motor into the circuit.
 
Personally I'd use the output of the 555 timer to switch a relay that would in turn switch the motor.
The 555 output is often sufficient to drive a relay coil but I prefer to use it to turn on a transistor that operates the relay coil as shown in the diagram.
I assume it would be best to operate the entire system from the 9V battery, a minor potential problem could be obtaining a relay with a 9V coil, they are usually 12V, 6V or 5V.
Whichever relay you use get one with a low coil power consumption to reduce the current drain on the battery. If you use a 6V or 5V relay with a 150mW coil then a value of 100 ohms for resistor R should reduce the battery voltage to that required by the relay coil.

If you have room for a second battery I'd install one as shown in the second diagram; it would compensate for the extra power usage and, more importantly, isolate the electronics from any potentially damaging voltage spikes generated by the motor.

I hope this is of some help.

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That looks a neat little module, My only concern is it's not obvious from the description how you trigger the timer to operate?
 
I'm looking at another similar unit. I need to make a phone call to their technical division to get more information. I'll keep you posted. I also cannot determine how the unit I posted operates.
 
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