230 v AC on Uc input pin

[SimonTHK]

Hello
I have to work with some old circuits that use some underground wiring to another circuit bleh blah.... in short terms. I have to accept that 230v is what I am supplied with as an input signal for my circuit, a signal that is switched on when a car drives by some old laser beam things.

Only the signal for an input pin that is. My circuit runs on its own supply.

How can I do this?

Would a trafo 230v to 5 v and acdc converter be the way to go?

Thanks in advance

 

[Reloadron]

Find a 230 VAC or 220 VAC to 5 VDC wall wart. Just make sure the wall wart for your given voltage does not exceed 5 VDC. That is what I would consider based on what you have mentioned.

Ron

 

[SimonTHK]

Like https://www.sparkfun.com/products/12889
Ofcourse that could be quite easy to do it like that ^^

 

[MikeMl]

Like https://www.sparkfun.com/products/12889
Ofcourse that could be quite easy to do it like that ^^

Hereabouts, the second-hand (Thrift) stores have lots of older transformer wall-warts which they practically give away (price is one third of Starbucks Coffee). They will switch off quicker than a lightly loaded SMPS type.

How fast an event are you sampling? You might have to put an artificial load on the wall-wart to more quickly discharge the internal capacitor...

 

[Diver300]

I would have thought that a relay with a 230 V coil, switching a 5 V signal, would be the way to go.

 

[SimonTHK]

I would have thought that a relay with a 230 V coil, switching a 5 V signal, would be the way to go.

I find those quite expensive, but I would have thought that aswell.

 

[Diver300]

https://uk.farnell.com/te-connectivity-schrack/rt314730/relay-spdt-250vac-16a/dp/1629051
**broken link removed**

They aren't very expensive, but I realise that a transformer may be essentially free.

 

[SimonTHK]

https://uk.farnell.com/te-connectivity-schrack/rt314730/relay-spdt-250vac-16a/dp/1629051
**broken link removed**

They aren't very expensive, but I realise that a transformer may be essentially free.

That price is free. I was not aware of this component, I was of the idea, that a kontakter might be the only way before. But I am noobie ^^ Ty perfect, what I do ofcourse.

 

[jpanhalt]

You haven't said what the data rate is. Have you considered an optoisolator such as this: https://www.fairchildsemi.com/datasheets/MI/MID400.pdf
John

 

[Nigel Goodwin]

I would have thought that a relay with a 230 V coil, switching a 5 V signal, would be the way to go.

That's only one of many ways to do it, there are plenty of options, many cheaper than that - although for simplicity it's well up there!

 

[SimonTHK]

That's only one of many ways to do it, there are plenty of options, many cheaper than that - although for simplicity it's well up there!

For me, that is practically for free. I can relieve it from taxes and am gonna buy like 10 for the use over 3 years xD it is as good as free.

 

[MikeMl]

Be aware that power relays do not do well switching a very small DC current. That type of relay relies on a bit of an arc to keep the contacts clean... Hard to do switching a couple of mA to a micro port...

 

[SimonTHK]

Be aware that power relays do not do well switching a very small DC current. That type of relay relies on a bit of an arc to keep the contacts clean... Hard to do switching a couple of mA to a micro port...

Cant I just have like a snubber and pull down resistoor?

 

[SimonTHK]

Be aware that power relays do not do well switching a very small DC current. That type of relay relies on a bit of an arc to keep the contacts clean... Hard to do switching a couple of mA to a micro port...

No wait, I understood your english now. Hmmm that sucks so you say that contacts will lose the surface for leading the eletricity? That kinda could suck