I have 8 of this circuit (image) connected in parallel.I am trying to operate a 5V dc solenoid for each circuit. I am using 5V 10 Amp external supply. The problem is when I try to turn on all the circuit using pins from the arduino the circuit seems to be lacking current to operate all the solenoids. When I try to connect all the solenoid in parallel without the circuit and supply all of them directly they seem to operate normally. Is there anything wrong with the circuit? Also when I operate the solenoid with the circuit only up to 4 solenoids can work at the same time.
A 2N3904 is a small-signal transistor (0.2Amp absolute max), and not able to switch solenoids >100mA.
Post a link to the solenoid.
If you switch an output pin high or low, you know it's high or low.
So why measure it with an input pin.
That diagram is making me dizzy.
Try drawing things the conventional way (assuming it's yours).
Signal from left to right, power supply up, and ground down.
How much current does each solenoid require and which Arduino?