Simple solenoid control

Can I use a solenoid without a transistor. One solenoid pin will be connected to 12V and the other pin to the MCU. When the pin connected to the MCU turns, ground, it will activate the solenoid and when switched to high, there is no path for electricity to move and offs the solenoid. Using a diode.

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michaelwylie over 11 years ago +2

The answer is no, for so many reasons, but the most important is that you will definitely, most likely, inevitably destroy at least that one pin if not the entire microcontroller.

0 kidiccurus over 11 years ago

Hmm, I would be careful doing that as I have a feeling the MCU might not be able to source enough current. Maybe one or 2 mill be OK if you are lucky, but I am not an expert on solenoids so do some extra reaserch before you try anything.
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0 bradnorwood over 11 years ago

I'd fry something lol transitor maybe needed.
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0 vsluiter over 11 years ago

Hi Royston,

Only one complete answer to be given here: check the datasheet of both the solenoid and the microcontroller. If your solenoid is very low power and you have a robust microcontroller that can sink a few mA, you might be in luck.
But a few mA, and a solenoid at 12V? That would mean that for 12V and 5mA (guessed value) the minimum coil resistance can be calculated to be R = V/I = 12/0.005 = 2400Ω . I'd guess you'd have a hard time finding a solenoid that has that resistance (or higher).

The other (bigger) concern that you will have, is that if you switch off the solenoid, there will be 12V on your microcontroller pin, and I wouldn't know of a microcontroller that would happily survive that.
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0 michaelwylie over 11 years ago

The answer is no, for so many reasons, but the most important is that you will definitely, most likely, inevitably destroy at least that one pin if not the entire microcontroller.
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