Joe,jph wrote: ↑Mon Jun 20, 2022 2:02 pm Presuming the top 2 diagrams are electromagnets and the lower two green round things are pushbuttons then no.
It appears that each pushbutton is connected to the HV side supply then to the electromagnet then to the open collector Darlington driver output.
Nothing will happen until you signal the ULN driver to turn on. That is a one way only process from Arduino to ULN input. The ULN input channels control the ULN Darlington Output Driver - Open Collector. There is no signal path back from the Darlington output to the Arduino.
IF the driver output is activate from the Arduino PRIOR to pushing a button then, if there is an mechanical latch with the electromagnet and pushbutton, it will latch as the driver stage is active. Without that signal FROM the Arduino FIRST though it wont.
IF it is as I presume - as I say above - then you could set the ULN output active by simply setting a logic 1 on the Arduino pin that corresponds to that ULN channel. The system is then ready to operate and latch. The is no communication of the push button state to the Arduino though.
You could also simply connect the push button to an Arduino input (so it is not connected electrically to the solenoid) and take the solenoid directly from the HV line to the ULN Darlington Collector. When the Arduino sees the push button pressed it can then activate the solenoid to latch. Whatever condition this is designed to operate in / and release in - can then be coded as you please. That way the Arduino is fully aware of the state of both the button and the solenoid and has full control over solenoid operation.
Joe
Did I just have the switches in the wrong place and they should be between the Arduino and the transistor?
I removed the lights to simplify....
Actually I dont think I really comprehend what I am doing here....