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What do you want this timer to do?

You can get a lot done with a 555 and a hexfet :D
 

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Discussion Starter #4
I know about 555 timer. But what's a Hexfet





Posted By Torby on 11/23/2008 7:38 AM
What do you want this timer to do?

You can get a lot done with a 555 and a hexfet :D
 

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A big transistor that can switch a lot of current with a small input.
 

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Again, the question is, what do you want it to do?
 

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Discussion Starter #8
Oh Sorry, Just run around for a minute or two. Stop , Run again. Just so it's not running continuoisly, to save on the battery power.
 

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Pretty simple. Consider:



With 90k resistors and 1000uf capacitor, it should go about 2 minutes on, pause for about a minute, then go again. The values of the resistors and capacitor aren't very critical if you're not too set on a specific time.

Most any FET should do. Maybe like this one: http://www.mouser.com/Search/ProductDetail.aspx?qs=70SGE8EoboQI56iMxMdH7w%3d%3d There's likely one that will do in the local Radio Shack's gray cabinet.

The circuit should work anywhere between 5 and 12 volts with this fet. The lower limit is the voltage needed to turn the fet full on.

If you want to fiddle with turning things on and off, get to know. They're the handiest things. I have a little drawer full of 35 amp fets, but they take like 10v to turn on, so you'd need a 12v supply.
 

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Um... divide the resistor values by 10. 90K, not 900K.
 
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