hi, sorry about that, I copied the wrong image from google images, just wanted to show the basic setup to connect the optocoupler. in case i was missing something. I have removed the picture so it does not confuse other people.the idea is I have a 60 to 80Vdc input, that I need to detect using a digital pin.is there any optocoupler or any other method where I can just put the 80Vdc and ground to it, and then get a signal which i can feed to the arduino input pin safely?
How can I find one that meets this requirements?
I need to detect 0Vdc or >60Vdc (system on).
QuoteI need to detect 0Vdc or >60Vdc (system on). Assuming that you need isolation.1. Get the optocoupler's datasheet. Find the current needed to light up the led.2. Get a resistor that will generate that current under 60v. You can size that resistor a little bit higher if you want to make sure that there is sufficient threshold.3. If you want to protect the opto-coupler for reverse polarity, put a diode on it, or another opto-coupler but reverse the polarity - in that case, you can detect ac as well as dc.4. Done.
just saw your message dc42.let me see if I understand the calculations.V=IR80 =0,01 * RR = 8000ohmsso similar to yours.about watts of resistor, i think i got it wrong, i guess i need small 1/4W resistors