Older and cheaper flashes can have up to 200V on those "two leads." That requires the SCR circuit or a mechanical relay.
Newer flashes can be directly connected to the Arduino but they will also work with the high voltage-tolerant circuit.
Older and cheaper flashes can have up to 200V on those "two leads." That requires the SCR circuit or a mechanical relay.
Newer flashes can be directly connected to the Arduino but they will also work with the high voltage-tolerant circuit.