This project is not for one with very little knowledge of mains electrical work, There are too many variables ( IFF’s or BUT’s) in your projectwalterwoj wrote: ↑Fri Mar 15, 2019 11:23 pmI'm looking for a suggestion for where to get (which ones to get) multiple relays (4) to use for power sensing inputs. I'm looking for 110vac input relays that can close a 3.3/5vdc circuit. preferably 4+ on one board or at least easily connected to the pi and wire used in pi projects. You thought are welcome!
I am going to wire my pi with a 8 channel relay board (already acquired) to control my garage. I will be controlling my furnace, 3 overhead light circuits (led lights, so low load), garage door (with input to tell if it's open) and my air compressor (I'll use a second heavier duty relay to keep from overloading the main relay). This question pertains to the overhead lights. I want to use the relay board in conjunction with 3 way switches so I have a fail-over way to switch the lights if there are issues with the pi. Because of this there would be no way to know if the lights are on or of when the relay switches (without knowing the position of the other switch on the circuit) I need to 'input' the light's state (powered or not). I've looked at CT type clamps and detectors but they are: 1.) Overkill, I don't need to know how much energy is flowing just weather it is or not: and 2.) too sensitive and probably prone to false positives without sufficient space between all the wires.(might detect flow in nearby wires) I'm open to other ideas for this solution but I think a 110v relay that closes an input on the pi to tell it if there is power is the best (so far).
Optocouplers give kilovolts of isolation.. Yes you need to add a diode or use an opto that has an AC compatible input. The capacitor I mentioned is to drop the voltage. Similar to a resistor but doesn't get hot.walterwoj wrote: ↑Sat Mar 16, 2019 5:35 pmdrgeoff: Generally optocouplers are low voltage and DC. I need 110vac on one end and 3.3/5vdc on the other. Also relays are by nature isolators for stepping up/down voltage or changing types of power (ac/dc)
All I'm really looking for is some recommendations on RELAYS, please? 110vac coil designed for project/maker work.
No, I have not suggested 110 volt optocouplers. You don't appear to understand the use of a capacitor as an AC dropper. Try googling that.
I note that on those diagrams the discharge resistor is directly across the mains input. On pretty much every other circuit I've seen for a capacitive dropper, the discharge resistor is connected across the capacitor.
That is why it has a discharge resistor. Those circuits are commonly used in LED lamps up to about 6W. The resistor has to discharge the capacitor quickly to stop people getting a shock from a bulb that has just been switched off and removed from the socket.
You should not encourage the untrained to build or workrpdom wrote: ↑Sun Mar 17, 2019 7:30 pmThat is why it has a discharge resistor. Those circuits are commonly used in LED lamps up to about 6W. The resistor has to discharge the capacitor quickly to stop people getting a shock from a bulb that has just been switched off and removed from the socket.