I need to find a way to on/off a motor automatically after about 5-7 seconds. Is it possible to do this ? help needed !

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Jayefuu8 years ago
Do you want it to come on, then off, then on, then off continuously? If so the circuit you want to build is called an astable.<br /> <br /> If you want it to come on for 5-7 seconds when a button is pressed and then go off until it is next pressed, you need to use a monostable.<br /> <br /> Either a monostable or astable are very easy to make, you just need a 555 timer IC from somewhere like maplin or radioshack and a few resistors.<br /> <br /> The 555 timer would output the timing, you'll probably want to put a transistor on the end so you a) don't damage the 555 timer b) get enough current for the motor.<br />
rukesh (author)  Jayefuu8 years ago
The links you sent were really helpful , thank you. I'm thinking more in the way of limit switches and relays. Is it possible? Just have difficulties with the circuit diagrams though.
rukesh (author)  Jayefuu8 years ago
Agreed...One could also purchase a premade off-delay relay, if it's just a one-shot following activation.
Great link.
mathews Jayefuu8 years ago
And a protection diode in parallel with the motor to prevent feedback into the transistor.
kramerr8 years ago
Jayefuu's answer is exactly what I was about to write. You didn't specify the type of motor you're using. If its an AC motor you'll need to do what Jayefuu suggested but use it to drive a relay, and use the relay to control the motor.

If its a DC motor, but very large you'll need to do the same thing or use a high power switching transistor.
rukesh (author)  kramerr8 years ago
We are planning to use a gear down motor, to make it move till it hits a limit switch.
boondocker8 years ago
 I was thinking about rigging an automotive turn-signal blinker relay. As amperage crosses the device, the heat caused by resistance makes a dissimilar metal pair flex (like an old-timey thermostat.)