turn a motor on for a set time

[madmikejt12]

hi, i was wondering if i could have a motor turn on for a set time when there is a current and then stop i.e if i connect a battery to it, it spins for say 5 seconds and then stops even though the battery is still connected
Thanks,
Mike

 

[Russlk]

Is it a DC motor? What is powering the motor when the battery is not connected? Why do you want to do this? What is the battery voltage? What is the rated voltage of the motor?

 

[Someone Electro]

Monostable 555 timer driving a MOSFET that drives a motor.

Not very hard to do.

 

[madmikejt12]

that was just an example, it is a 10v dc supply from usb and the motor is aprox 6-9v and i want to do this so that the keyboard drawer opens when computer it turned on, it is quite small (only just fits a standard keyboard on)

 

[Dr.EM]

I would doubt the USB being able to supply enough current to power a motor to do that :?:

 

[madmikejt12]

if there isnt enough current, i will use a bfy51 transistor to amplify the current

 

[Someone Electro]

You can anplefy curent! Whith an transistor you can only swicth an biger curect source.

You can always use an wall wart to pover it in case 500mA from the USB is not enugh

EDIT: Oh and USBs power line is 5V not 10.

 

[madmikejt12]

You can anplefy curent! Whith an transistor you can only swicth an biger curect source.

You can always use an wall wart to pover it in case 500mA from the USB is not enugh

oh yes.....
i have an old psu from a dell computer that i was going to use for multiple projects but i dont know what pins to connect the switch to and we no longer have the pc

i have a few wall plugs with various voltage/current but how would i get it to switch on when the computer is switched on?

 

[madmikejt12]

oh yes im thinking of the molex connectors inside the pc lol, could use one of those

 

[madmikejt12]

wont the 555 astable circuit just turn it on then off then on then off..... untill the power is off?
that would be interesting, turn on the pc and watch the keyboard tray go in and out :lol:

 

[Nigel Goodwin]

wont the 555 astable circuit just turn it on then off then on then off..... untill the power is off?
that would be interesting, turn on the pc and watch the keyboard tray go in and out :lol:

You can use a 555 in either astable or monostable modes!.

 

[madmikejt12]

so, does that just go on and then off?

 

[Someone Electro]

Yep.

Oh and the the power conecotr of r a CD drive could be good.The 12V line may be useful.Also no wryes about curnent.there are amps of curent there.

 

[madmikejt12]

ok thanks
thats what i was talking about when i said the molex connectors (got a bit mixed up with the voltages from the usb and cd connectors :roll: )

 

[Someone Electro]

You can find the cirucit in the 555 timers datasheet

Datasheet is here :arrow: **broken link removed**