Hi,
I'd liket o use arduino to control a device that can only be switched on by pressing the power button.
I want to wire arduino pins to the internal switch so that I can use arduino to control the device.
What kind of signal or code do I need to use to press-a-button, in other words to send a short-circuit signal, if that makes sense 
I'd appreciate your help in this.
Look at this:
You would then use pin 13 to control:
LarryD:
Look at this:
digitalRead() - Arduino ReferenceYou would then use pin 13 to control:
Powerswitch tail 2 : ID 268 : Adafruit Industries, Unique & fun DIY electronics and kits
Thanks for this, but all I need to do is to be able to short two pins of a device that requires me to press the button.
Then have pin 13 control a relay.
I changed the title slightly...
I always have difficulties decoding these diagrams, is there any way to do this? I think what you're trying to show me is a physical switch/relay. I think I can use these ~~http://tinyurl.com/pmh9mja~~ http://www.ebay.com.au/itm/290562086704 but that's still not what I need now.
In simple words I want to imitate a momentary switch.
See:
So are you saying that using this kind of relays is the way to do what I want to do? I suppose I can, can't I :.
How about Solid State Relay? ~~http://tinyurl.com/pmh9mja~~ http://www.ebay.com.au/itm/290562086704
Your link does not work for me.
This is a solid state relay so the output is not a dry contact.
It says it will work at 3-32 input volts @ 5 to 25 ma so the Arduino could drive it.
Yes you're right.
Ok, I got it now, thank you.
Last question: Can I use that SSR to power on/off ~3000W (probably less) from 220V?
3000W / 220V = 13.6 Amps.
Your SSR says it can handle up to 25 Amp DC.
Is your 220 AC or is it DC?
It's a 'standard' UK voltage 230V 50Hz and I believe this is AC.
You'll have to use a relay.