Not without more information about the relay board and the circuit on it. But DO NOT use a Vcc greater than 3V3 for connection to a Pi. 5V in the wrong place (GPIO input) can destroy a Pi very quickly
I will have too see if I can scare up a 3.3v dc source. I only have the 5v power supply I bought for the PI. I will test the other input and outputs too, I just used #3 because it was easy to access.JohnsUPS wrote: ↑Sun Mar 31, 2019 11:37 pmSame test as above, but with VCC = 3.3VDC. If the output is above 3VDC or so, it should have no problem being recognized by the Pi (forget what the exact input voltage low threshold is at the moment).
The move your high side input to L2, and measure OUT2, then L3 & OUT3 just to be sure all of the channels are working.
Because the advertisement for the board states that that it should be able to run between 3 - 5 Vdc, it should work on 3.3VDC.
Makes sense.walterwoj wrote: ↑Mon Apr 01, 2019 12:20 amFor example: if I put a wall switch in my house and turn it off, if I test for voltage at the light, guess what voltage I will get? 0 volts! Every time! On every switch in the house! If you get 0.05 VAC on the output of a house switch you have a defective switch!
And another thing: Active LOW?! That is the house hold equivalent of putting the switch on the ground wire which is a complete no-no. Again no electrician would do that and no code would allow it either as it is VERY DANGEROUS if someone ever tried to work on the system later.
Whatever is being fed by electronics such as a Pi's GPIO can itself be more-or-less an open-circuit - the gate of a FET for example takes no current.I read that (and have observed on my PI ) 'floating' can occur on the pi (and other electronics apparently) where the switch is 'off' yet there is voltage up to half of the active voltage.
You are right it is not a relay, I am used to relays of the mains voltage and above type so that's how I think of it, but your right it it is really opto-isolators with what appears to be Active low output (is that an oxymoron? active low and output since it is really taking voltage in?)Burngate wrote: ↑Mon Apr 01, 2019 5:06 pmOne of the things that initially bemused me was that "3 Channel AC 220V Optocoupler Isolation Board AC Detection Testing Module" being referred to as a relay - it isn't.
Without having one in my hands, I can't be sure, but it appears to take in three phases and neutral, rectify them, and pass the resultant DC through 150k to optoisolators.
Their outputs seem to be presented to some sort of transistor which could possibly be wired as open-collector. Or maybe not.
Since you have it in your hands, you can tell us what ICs are on it and how the components are hooked up and we can figure it out. As @burngate already mentioned, the high voltage side is pretty easy to figure out. Each phase goes through a diode bridge via the big ass resistor to rectify it, the cap provides smoothing, then it goes to the optoisolators. Knowing the numbers on those ICs will tell us what kind of output is on the low voltage side (so the three black ICs next to the Q's. Then if possible if you can read the flat face of the Qs we can see what kind of transistor is being used. The two resistors, one is for current limiting of the LED, but interested on where the other one is hooked up to Q and how both are interfaced to Vcc and GND.
It's for detecting 110V, which the OP believes he is competent to handle (but see my earlier post). So it needs a relay with a 110V coil.
And what powers the relay contacts and opto input? Another isolated supply? Or a Pi-derived supply? If the former, good, but do you really need two lots of isolation? If the latter, the opto achieves nothing.LTolledo wrote: ↑Mon Apr 01, 2019 9:53 pmIf it were me I'd probably use a normal (industrial grade) relay with a coil rated 200 ~ 240v (like the Omron G2R-1-S, in socket P2RF)
to provide additional isolation a 3v optocoupler unit to be connected to the relay output contacts.
the optocoupler 3v outputs to RPi GPIO.
Ya if I were to use a 120Vac activated relay to sense is the 120V is on or not, then stupid easy way to do it is have the contacts simply connect the Pi's 3.3V to a GPIO input pin. No optoisolator or other components requires. The contacts are already isolated from the high voltage side with the coupling being magnetic now rather than optical.And what powers the relay contacts and opto input?
1 Three way 220/120 ac voltage monitoring unit £ 12.00ptimlin wrote: ↑Tue Apr 02, 2019 12:38 amYa if I were to use a 120Vac activated relay to sense is the 120V is on or not, then stupid easy way to do it is have the contacts simply connect the Pi's 3.3V to a GPIO input pin. No optoisolator or other components requires. The contacts are already isolated from the high voltage side with the coupling being magnetic now rather than optical.And what powers the relay contacts and opto input?
Sounds like he only needs two. So £ 20 for the relays
How is it that you require a box for the relays but not one for this exposed circuit board? So be sure to add in the costs associated with mounting that ac voltage monitoring board.