replacing a push-button in an existing device

Dear Arduino users, may be, this is a very simple question - but I would like to ask you.- I want to replace a push-button in the controlling unit of an existing device (a cooling box), by switching with the Adruino Digital OUT.

What components could I use here? (optocouplers, transistors, relays)

thanks for any help

frank

Optocouplers, transistors and relays would all be good suggestions, depending on the voltage and current you need to switch.

High voltage or current is best switched with a relay.

If the voltage and current is low an optocoupler is a good choice because that way the device and your Arduno are not "electrically connected".

Dear MikMo, thanks for your posting.- I´m unsure what optocoupler to use.- There are so many types (linear, with transistor, with triac). - I simply want to control the optoc. with 5V/0V from the digital OUT of the Arduino. On the other side should be the 2 Pins of the micro touch-button of my device.- Do you´ve a tip for me, what optoc. to use?

thanks!

frank

I simply want to control the optoc. with 5V/0V from the digital OUT of the Arduino

To the Arduino an opto looks exactly like an LED so put a series resistor to limit the current and drive it like an LED. On the other side it sounds like you simply need a transistor so identify the most positive side of your push button and connect it to the collector, then the other side to the emitter. Yes there are a lot of optos to choose from. You need digital or liner and as cheap as you can get. That should see you right.

ok.- I think I got it.- So with this optoc LNY74-2H (http://www.datasheetcatalog.org/datasheet/vishay/83526.pdf) I could connect the collector and emiter parallel to my push-button.- Yes?

thanks!

frank