I need some help on this Arduino project. The breadboard wiring I did isn’t working for power delivery and we haven’t connected everything up thus far. I’m getting a drop in voltage when I turn on two devices, the amp pull jumps, and I blew the capacitor.

1x Arduino Uno Rev 3

1x Pololu A4988 Stepper Driver

3x MOSFET Drivers

3x Solenoid

1x Nema 8 Stepper Motor

1x Grove Relay

Right now I’m powering the Stepper driver and one Mosfet driver with a 12-v power supply. The Arduino is powered by a USB from the computer. With that said, I can run both the motor and Solenoid separately with no issues. However, when I run both, the voltage on the power supply drops from 12v to 7v, and the amperage jumps from .3 to 1.5A. I also start getting a lot of jitter in the motor depending on the delay and step size it's currently set to. The main system is going to need to run the three solenoids the motor Arduino and the relay in various combinations of on/off.

The A4988 and the Mosfet drivers can take higher voltage, so I attempted to smooth things out by increasing the voltage and I popped the 100uF capacitor. So I figured, I should step back and ask for some help before I cause any more damage.

right now I have the power plugged into a housing connector on the breadboard that I soldered down and I'm just running power and grounds directly to each of the device's power inputs. Wires are just soldered together to make the connections.

I'm not an EE, so this is new territory for me.

Would like your insight and would be interested in learning what I should look at when I come across other projects like this.

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  • \$\begingroup\$ The voltage dropping looks like the PSU is limiting. What's the current rating on the PSU, what's the current when you run the solenoid/Motor? Did you exceed the voltage rating of the capacitor? \$\endgroup\$
    – LordTeddy
    Apr 26, 2023 at 11:07
  • \$\begingroup\$ @LordTeddy OMG, the power supply was set to 1.5A. The draw on the Mosfet driver w/solenoid is 1.8A alone. So for all three to work, I'll need a power supply with at least 6A capable, plus what ever the Arduino and relay will need. is that correct? That was such a newb mistake. Sorry for wasting your time. \$\endgroup\$
    – Michael
    Apr 26, 2023 at 11:25
  • \$\begingroup\$ Sounds right to me. Because you asked a complete, easy-to-understand question, it took me all of 30s to answer, so you haven't wasted any time. \$\endgroup\$
    – LordTeddy
    Apr 26, 2023 at 13:46


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