mosfet as a switch, manual over-ride switch?

Using Arduino General Electronics
1

Hi,

I have a mosfet that is used as a switch to control a solenoid valve. The mosfet is controlled by an Arduino.

Is it safe to add a switch between the drain and source to function as a manual on/off switch for the valve and will this be OK to use when the mosfet gate is high as well as low?

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2

That would turn the solenoid ON, but would fail to turn it OFF if the mosfet is conducting.

3

Add the manual switch between Source and Gnd. If the mosfet isn't grounded, your circuit will be open and the solenoid won't fire.

4

What is the purpose of the switch?

  • switch it off when already on or switch it on when already off?
  • keep it in the switched state permanently (toggle switch) or only as you press the switch (momentary button)?
5

You can't add a manual ON/OFF switch.

You can add however:

  • A manual off switch
  • A manual on switch
  • or on/off/auto switch :wink:
6