Auto push start button after power outage

[jimg]

I recently purchased a d-link dns323 storage unit. It works well, the only problem is it doesn't start up automatically after a power outage, you have to press a button.

By testing, it takes a little over a second after the power is applied before pressing the button has any effect. When the power is applied, there is 12 volts on one pin of the switch. Connecting an ammeter across the switch, it seems to draw about 2ma, but it could be higher briefly at turn on.

There are probably a lot of circuits to do this, but I couldn't seem to find one.

So, I need a SAFE circuit to wait say 2 seconds after power comes up, and connect the circuit between the pushbutton pins briefly. I can come up with a dozen hairbrained schemes, but I thought I would ask the experts for something safe. Has anyone done something like this they would like to share?

 

[MikeMl]

Are you trying to power this from the voltage across the open switch, or do you have another source of power to run it? If so, the circuit would have to operate on uA of current until the time elapses, at which point it would have to draw > 2mA for a second, and then go back to sleep where it draws almost nothing again.

 

[dougy83]

I take it you've already removed the case of the unit, so there's no problem putting some electronics junk inside it. Maybe this circuit will do the trick. It delays for a few seconds before pulsing for a second or so.

 

[jimg]

Are you trying to power this from the voltage across the open switch, or do you have another source of power to run it? /QUOTE


Either way would be fine. I just want it to be safe as this unit will have all my wife's photos and to destroy it would definitely not be good. My first thought was a mosfet across the switch driven by a 555 oneshot. But as I say, probably a hairbrained idea.

 

[jimg]

I take it you've already removed the case of the unit, so there's no problem putting some electronics junk inside it. Maybe this circuit will do the trick. It delays for a few seconds before pulsing for a second or so.

I like it. Thanks.

 

[jimg]

I used a 20 year old 4093 I found in my junkbox, a 2n2222, and a 2.2M/1uf for first stage as I didn't have a 3.3uf non electrolytic.

It worked good, thanks.