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My project consists of one 5 V solenoid (but uses 3.3 V), one voltage regulator (5 V to 3.3 V), one diode, two N-channel MOSFET transistors, and one 5 V LED strip, all controlled by a Raspberry Pi Zero. According to my power supply, the solenoid pulls 0.75 A at 3.3 V and the LED strip pulls 0.19 A.

Do I need another diode for the MOSFET connected to the solenoid? Since it's a logic level MOSFET I'm assuming it doesn't but for the sake of the diagram, do I?

Also this is my first time making a circuit diagram, please critique me if it looks wrong or I'm missing any valuable info!

enter image description here

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  • \$\begingroup\$ Should that be IRLZ34? \$\endgroup\$
    – Tim Williams
    Commented May 20 at 21:11
  • \$\begingroup\$ Why are you only running the solenoid from 3.3V? \$\endgroup\$
    – Finbarr
    Commented May 20 at 21:44
  • \$\begingroup\$ @TimWilliams actually it's supposed to be IRLZ44NPBF for it to be wide enough for the solenoid. I fixed the pic, sorry about that! \$\endgroup\$
    – alxzhu
    Commented May 20 at 21:58
  • \$\begingroup\$ @Finbarr it gets really hot at 5V and the 3.3 is the min amount of voltage for it to move the same amount \$\endgroup\$
    – alxzhu
    Commented May 20 at 21:59

1 Answer 1

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D3 will turn on making the solenoid is active. It isn't really nessacary to the circuit so remove it or reverse it. The IRFZ34N probably has a bypass diode in it, so unless you are expecting a large current, remove D3

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  • \$\begingroup\$ Sorry if this is a stupid question, but would I be wrong to assume that this circuit might not pull a large amount of current? \$\endgroup\$
    – alxzhu
    Commented May 20 at 22:02
  • \$\begingroup\$ Depends on what the soleniod draws, what is the series resistance. (you also need to put in the series resistance) \$\endgroup\$
    – Voltage Spike ♦
    Commented May 20 at 22:03
  • \$\begingroup\$ So the resistance of the solenoid is R=V/I = 3.3/75mA = 44 ohms. For the series resistance, should I also add the diode? \$\endgroup\$
    – alxzhu
    Commented May 21 at 3:27

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