230V AC -> 5V DC

Hello Everybody

I have very limited skills in electronics and would appreciate some support for this little problem. How do I turn 230V AC into a +5V DC voltage to trigger a digital-in on my arduino.

It will take a capacitor to flatten the AC and a voltage divider - that much I know. But I have no clue what capacitances and resistances should be.

In the end I would like to trigger on the fuel pump of my central heating system and record up-time of the burner.

Thanks so much Sebastian

Simplest way is to buy a small 5V plugpak. Will be cheaper than any alternative which is safe.

OK guys, he didn't want a power supply, he wants an indication to an input on the Arduino.

When you get the question correct, the answer is an AC optocoupler (PC814) (readily available on eBay). |500x492

This (its LEDs) needs to be connected in series with an AC rated capacitor and resistor and the photo-transistor between ground and the Arduino input using INPUT_PULLUP. The code will detect the pulsating logic level - it can be either de-bounced, or used to synchronise with the AC peaks.

If deemed too risky to construct, "reverse" SSR modules are readily available to perform this function.

Yeay, a opto is indeed the way I would use if I really had to use 230V AC as an input. But as the topic starter is not that skilled (otherwise a power supply was easy for him) I would say a simple wall wart or just a USB charger is way saver. And to stop it from feeding the Arduino when that's powered off, just use a 100k or so resistor in line (aka, in series) with that charger. It's a simple plug and go solution :)

All solutions that involve direct access to mains voltage should only be adopted by qualified and experienced users. In that respect, may be a simple plugpack is safer..

Thanks for your suggestions so far!

To be more clear: I need to detect the ON-state of a 230V driven pump. And the OFF-state. Typical ON/OFF times are 10 minutes. I do not care for nor do I want to even sense the 50Hz.

I'm regularly working on our electrical system and I'm familiar with the hazards of 230V. Plus I have a physics background so I should know theoretically;-)

The optocouplers appear to be the most elegant solution. If they can be driven by 230V - perfect!

What exactly are those reverse SSR modules? Do they down-convert 230V AC to a low voltage (AC or DC)?

Cheers Sebastian

In the end I would like to trigger on the fuel pump of my central heating system and record up-time of the burner.

A 220 usb wall charger could supply a 5v output when 220vac is present and 0v output when 220vac is not present.

http://www.ebay.com/sch/i.html?_odkw=usb+wall+charger+230&_sop=15&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313.TR0.TRC0.H0.Xusb+wall+charger+220.TRS1&_nkw=usb+wall+charger+220&_sacat=0

zoomkat: A 220 usb wall charger could supply a 5v output when 220vac is present and 0v output when 220vac is not present.

http://www.ebay.com/sch/i.html?_odkw=usb+wall+charger+230&_sop=15&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313.TR0.TRC0.H0.Xusb+wall+charger+220.TRS1&_nkw=usb+wall+charger+220&_sacat=0

Yes - maybe that's actually the easiest and cheapest way to go - Thanks

[u]From Reply#1[/u]

Simplest way is to buy a small 5V plugpak. Will be cheaper than any alternative which is safe.

raschemmel: [u]From Reply#1[/u]

OK - I get it :-) Thanks to all!

Hmmm. Seems my replay was not #2 when I wrote it, else I would not have refereed to "guys". Apparently some were retracted.

Anyway, I stand by my answer as the neatest way to do it - for an experienced engineer.

If you are fussy about working with mains, then yes, a plug pack is the way to go.

Of course, it must be a reputable brand, as the "cheapies" from China have a bad reputation. I acquire what appear to be genuine ones (that came with the phone) at Garage Sales, never for more than $1.

And - this was recently posted on another thread.