Bakground:
I am designing a smart controller for an existing heating system. The system and pumps are controlled by 200V AC latching relays. As an interface to the existing controller, these are controlled by 24V DC relays. As a Mechanical Engineering I understand some basic electronics but not best practices and detailed infomation.
What I am trying to achieve?
To switch each relay from an ESP32 board that will be controlled from Home Assistant. Each pump has an ON and an OFF relay. Each relay only needs to be energised for 500ms or so. This can be programmed in Home Assistant. The switch in the diagram will be an output of the ESP32.
Additional Information
Relays are Omron MY2-D
All of the relays are already wired as common ground
Optocouplers I have bought are PC817
I have a range of transistors if needed
My Question...
Can I control these relays reliably just using optocouplers? Or is it best practise to also use a transistor? The relays have a resistance of 662Ω so I believe this acts as a current limit.
If optocoupler is off then it requires a pulldown resistor (10k in picture) to avoid the output floating?
I am designing a smart controller for an existing heating system. The system and pumps are controlled by 200V AC latching relays. As an interface to the existing controller, these are controlled by 24V DC relays. As a Mechanical Engineering I understand some basic electronics but not best practices and detailed infomation.
What I am trying to achieve?
To switch each relay from an ESP32 board that will be controlled from Home Assistant. Each pump has an ON and an OFF relay. Each relay only needs to be energised for 500ms or so. This can be programmed in Home Assistant. The switch in the diagram will be an output of the ESP32.
Additional Information
Relays are Omron MY2-D
All of the relays are already wired as common ground
Optocouplers I have bought are PC817
I have a range of transistors if needed
My Question...
Can I control these relays reliably just using optocouplers? Or is it best practise to also use a transistor? The relays have a resistance of 662Ω so I believe this acts as a current limit.
If optocoupler is off then it requires a pulldown resistor (10k in picture) to avoid the output floating?