# few second Delay question

Discussion in 'The Projects Forum' started by RiG615, Nov 13, 2008.

1. ### RiG615 Thread Starter Active Member

Nov 13, 2008
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I want to know how to make a delay circuit of some sort
I want a delay time of anywhere from 4 to 10 seconds after i click a switch

1.5V DC > delay > motor on

thanks

2. ### Wendy Moderator

Mar 24, 2008
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Last edited: Nov 13, 2008
3. ### RiG615 Thread Starter Active Member

Nov 13, 2008
50
0
1.5 V would be the voltage from the battery running the [small] motor, not the trigger signal
what kind of current/ voltage can this thing handleor need(does it need 9v)?

also what does this one add to the other one?

im kind on new to all this stuff

4. ### mik3 Senior Member

Feb 4, 2008
4,846
63
A simple method is to take a 5VDC relay (the coil voltage is 5VDC) and use a 9V battery say to activate it. Of course you will a series resistor with it to limit the current and dont destroy it. If you connect a capacitor in parallel with the relay coil you will get a delay and then the relay will be activated. In simple words, the delay will depend upon the capacitors value, the larger the capacitor the greater the delay.

5. ### RiG615 Thread Starter Active Member

Nov 13, 2008
50
0
Instead of using the 555 timer could the formula T=CxR and use a 1000µF capacitor and a 1 k ohm resistor to create a delay of about 5 seconds?

im confused to how this will effect the voltage and current to the [mini]motor

-also i only need the motor on for about 3 seconds.

thanks

6. ### mik3 Senior Member

Feb 4, 2008
4,846
63
Yes you can but the time wont be actually RC, its depends on the relays pull-in voltage and the resistance of the relay coil. You can use another relay with a capacitor in series with it as to stop the motor after 3 secs.

7. ### RiG615 Thread Starter Active Member

Nov 13, 2008
50
0
I'm working on a circuit design, but in the mean time....

How durable are relays and capacitors? motors?
can they be dropped, thrown ?
can they be thrown consistently in a padded environment?
does engulfing everything in glue help??

8. ### RiG615 Thread Starter Active Member

Nov 13, 2008
50
0
Can a capacitor [say 1000 micro farads] hold open a relay for at least 5 seconds
say this capacitor?
-using a 9 volt battery to charge-