18V => 5V Step-Down

[dakky]

Hello

i'm looking for a 18V => 5V (dc/dc) and vice versa converter. Someone can give me a hint, where to look for a suitable solution?

Background: Our intercom (doorbell/opener) is running in 18V, which would kill my arduino input (bell) and output pins

[mfalkvidd]

Are you planning to power the Arduino off the 18V? Or do you only need to be able to measure or control the 18V signals?

Measurement can be done with a voltage divider and control can be done with a relay. But then you'd need a separate power supply.

[hek]

Use one of these:
http://www.ebay.com/itm/5pcs-LM2596-DC-Adjustable-Buck-Converter-Step-Down-Power-Supply-Module-1-23-30V-/161833990353?hash=item25ae0eb8d1:g:MdYAAOSwHjNWALgz

[ericvdb]

Keep in mind that often doorbells are AC, and not DC.

[dakky]

Thanks 4 all the input!

I thought about measuring only, but powering the node is a possibility i nearly ignores. Stupid me
This intercom has a regulated 18v DC power source. So i should be fine.