Push Button Switch bypass

[Nemo1966]

I am trying to bypass a push button switch on my ext HD unit.

The Ext HD when plugged in does not power up straight away. It has a push-button on the front that you have to press to get it to fire up. If you turn if off at the main and turn it on again, you have to press the front button again to power the device on

There are 3 wires that go to the switching unit. Does anyone know how to hot wire it so that the unit comes alive directly from power up?

Pics of switching unit:
**broken link removed**
**broken link removed**

thanks in advance

 

[BF9000]

It looks like an Omron switch with 2 switching leads and a grounding tab. To bypass this (i.e. make switch always be closed) simply connect the two leads together with a small peice of wire.

There is the possibility that the rest of the circuitry actually requires the switch to be open when the device is powered on. This would be the case if the circuit that monitors the switch is looking for a rising/falling edge on the switch to activate the function. If this is the case you can solder a resistor and capacitor in series with the two switch leads so that the signal accross the switch will change after a short time delay.

 

[philba]

before you go and make a change, you should understand why it was designed that way. I suspect that hot plugging leads to all sorts of wierd voltage transients. think of it as contact bounce on steroids. I would be very conservative on powerup delay if you go that route.

 

[Nemo1966]

before you go and make a change, you should understand why it was designed that way. I suspect that hot plugging leads to all sorts of wierd voltage transients. think of it as contact bounce on steroids. I would be very conservative on powerup delay if you go that route.

Yes thanks..... struggling with trying to work out what capacotor and resistor to use. Pretty new to this stuff

thanks

 

[Nemo1966]

OK after more investigation it seems the device doesnt need a constant voltage across the switch. Ive connected the switch to a relay and If i flick the relay on and off then the unit starts up. Flick the relay on and off again and the unit turns off.

What i would like to know is can this functionaly be mimicked in electronics?

e.g a capacitor (or other) that on power up will delay 3 seconds then once charged send a short 12v burst and then become inactive again?

thanks

I suppose the easiest way would be to buy a ext HD case with a proper on off button (e.g. one that stays on or off)

 

[qsiguy]

To back up a bit, I think I would first experiment by holding down the on button while you are plugging in the drive and while removing it and see how it responds. I've tried similar things on some circuits that if you held down the button it wouldn't work as it was only looking for a short pulse.

If it works when holding down the button for a long period and while connecting and disconnecting the drive you could just hard wire it on all the time like you originally wanted to do.

To answer your question "can this functionaly be mimicked in electronics?", the answer is yes. You can mimick just about anything. I know you could use a 555 timer IC to make a circuit but someone else might have a simpler circuit. I'd have to do a little research to come up with a circuit for you. Someone else might have a good one ready to show you.